JOINING OF LEAD AND LEAD ALLOYS

Abstract

A method of joining a first metal and a second metal is described. The first metal comprises Pb in an amount of at least 50 wt. % by weight of the first metal. The method comprises fusing the first metal and the second metal using non-consumable electrode arc welding.

Claims

1. A method of joining a first metal and a second metal, wherein the first metal comprises Pb in an amount of at least 50 wt. % by weight of the first metal, the method comprising: fusing the first metal and the second metal using non-consumable electrode arc welding.

2. The method according to claim 1, wherein the first metal comprises Pb in an amount of at least 75 wt. %.

3. The method according to claim 1, wherein the second metal comprises Pb in an amount of at least 50 wt. % by weight of the second metal.

4. The method according to claim 1, wherein the first metal and/or the second metal consists of: Ag in an amount from 0.0 to 2 wt. % Ca in an amount from 0.0 to 1 wt. %; Sb in an amount from 0.0 to 25 wt. %; Sn in an amount from 0.0 to 10 wt. %; and balance Pb and unavoidable impurities.

5. The method according to claim 1, wherein the first metal and/or the second metal is according to UNS L50000 to L50099, UNS L50100 to L50199, UNS L54000 to L55099, UNS L52500 to L53799 or L50700 to L50899.

6. The method according to claim 1, wherein the method comprises preparing a butt joint between the first metal and the second metal, and wherein fusing the first metal and the second metal comprises fusing the prepared joint.

7. The method according to claim 6, wherein the butt joint has a thickness in a range from 1 to 20 mm.

8. The method according to claim 6, wherein the butt joint is a single-sided butt joint or a double-sided butt joint.

9. The method according to claim 1, wherein the non-consumable electrode arc welding comprises non-consumable electrode arc welding the first metal and the second metal without welding backing.

10. The method according to claim 1, wherein the non-consumable electrode arc welding comprises non-consumable electrode arc welding the first metal and the second metal in a flat position.

11. The method according to claim 1, wherein the non-consumable electrode arc welding comprises non-consumable electrode arc welding at a rate of from 1 to 100 mm s−1.

12. The method according to claim 1, wherein the non-consumable electrode arc welding comprises providing a protective atmosphere comprising Ar and unavoidable impurities, at a flow rate in a range from 1 to 20 l min−1 or comprising Ar+1 to 5% H2 and unavoidable impurities, at a flow rate in a range from 1 to 30 l min−1.

13. The method according to claim 1, wherein the non-consumable electrode arc welding comprises using a thoriated tungsten electrode, comprising from 1.7 to 2.2 wt. % thorium, having a diameter in a range from 1.0 mm to 3.2 mm, a diameter at tip in a range from 0.125 mm to 1.5 mm, a taper length of from 1.5 to 3 times the diameter, a constant included angle in a range from 12° to 90° and/or a pointed or a truncated tip.

14. The method according to claim 1, wherein the non-consumable electrode arc welding comprises current control welding, at a current in a range from 3 A to 300 A or wherein the non-consumable electrode arc welding comprises alternating current (AC) welding at a frequency in a range from 10 Hz to 70 Hz.

15. The method according to claim 1, wherein fusing the first metal and the second metal comprises autogenous fusing.

16. The method according to claim 1, wherein the non-consumable electrode arc welding comprises single pass welding.

17. The method according to claim 1, wherein the non-consumable electrode arc welding is gas tungsten arc welding.

18. The method according to claim 1, wherein the non-consumable electrode arc welding is plasma arc welding.

19. A component provided at least in part, by joining according to the method of claim 1.

20. (canceled)

21. An apparatus for joining a first metal and a second metal, wherein the first metal comprises Pb in an amount of at least 50 wt. % by weight of the first metal, the apparatus comprising: a non-consumable electrode arc welding unit configured to perform the method according to claim 1; and optionally, a first industrial robot configured to fuse the first metal and the second metal using the non-consumable electrode arc welding unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0184] For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic Figures, in which:

[0185] FIG. 1 shows the melting point of binary Pb alloys as a function of the content of alloying additions of Sn, Bi, Te, Ag, Na, Cu and Sb;

[0186] FIG. 2 shows the dynamic viscosity η.sub.Pb of liquid lead as a function of temperature;

[0187] FIG. 3 shows the surface tension of liquid lead as a function of temperature;

[0188] FIG. 4 shows the electrical resistivity ρ.sub.Pb of liquid lead as a function of temperature;

[0189] FIG. 5 shows the thermal conductivity λ.sub.Pb of liquid lead as a function of temperature;

[0190] FIG. 6 schematically depicts different categories of butt joints;

[0191] FIG. 7 schematically depicts welding positions defined according to the American Welding Society;

[0192] FIG. 8 schematically depicts a method according to an exemplary embodiment;

[0193] FIG. 9 is a photograph of a weld according to an exemplary embodiment;

[0194] FIG. 10 is a photograph of a longitudinal cross-section of a weld according to an exemplary embodiment;

[0195] FIG. 11A schematically depicts a joint for a method according to an exemplary embodiment; and FIG. 11B schematically depicts a joint for a method according to an exemplary embodiment;

[0196] FIG. 12 shows a graph of tensile stress as a function of displacement of tension test specimens of a first metal;

[0197] FIG. 13 shows a graph of tensile stress as a function of displacement of tension test specimens of a second metal;

[0198] FIG. 14 shows a graph of tensile stress as a function of displacement of tension test specimens of a weld according to an exemplary embodiment of the first metal of FIG. 12 and the second metal of FIG. 13;

[0199] FIG. 15 shows photographs of the tension test specimens of the first metal of FIG. 12, after testing;

[0200] FIG. 16 shows photographs of the tension test specimens of the second metal of FIG. 13, after testing; and

[0201] FIG. 17 shows photographs of the tension test specimens of the welded first metal and second metal of FIG. 14, after testing.

DETAILED DESCRIPTION OF THE DRAWINGS

[0202] FIG. 8 schematically depicts a method according to an exemplary embodiment.

[0203] Particularly, the method is of joining a first metal and a second metal, wherein the first metal comprises Pb in an amount of at least 50 wt. % by weight of the first metal.

[0204] At S801, the first metal and the second metal are fused using non-consumable electrode arc welding.

Experimental

GTAW—DC Welding

[0205] GTAW welding was performed using a TWECO® ARCMASTER® 301TS using Stainshield TIG (Example E1) or Pureshield Argon (Example E2) at a flow rate of 10 litres/minute, for welding of an anode blade lead alloy, having a composition of Pb—1.5 wt. % Sn—0.08 wt. % Ca. That is, the first metal and the second metal have a composition of Pb—1.5 wt. % Sn—0.08 wt. % Ca and are plates, having a thickness of 6 mm. Closed square butt joints between the first metal and the second metal were prepared and the prepared joints were fused autogenously, by welding from both sides (i.e. double welded, closed butt joints) in a 1G position according to the parameters of Tables 11 to 12, at a speed of 30 mm s.sup.−1. Default parameters were used otherwise. Metals having different thicknesses may be welded at corresponding welding currents and/or speeds. For example, relatively thicker metals may be welded at relatively higher welding currents and/or relatively lower welding speeds, while relatively similar metals may be welded at relatively lower welding currents and/or relatively higher welding speeds, for example scaled such as linearly according to thickness. The water-cooled torch was held and moved using a first industrial robot (i.e. automated).

TABLE-US-00012 TABLE 11 TWECO ARCMASTER 301TS parameters. Parameter Description Value E1 Value E2 Shielding This parameter operates in GTAW modes only 0.2 s 0.5 s gas pre-flow and is used to provide gas to the weld zone time prior to striking the arc, once the torch trigger switch has been pressed. This control is used to reduce weld porosity at the start of a weld. Start current This parameter operates in GTAW modes only 100 A (67%) 5 A (1%) AS and is used to set the start current for TIG. In 4T mode the Initial Current remains on until the torch trigger switch is released after it has been depressed. In 2T mode the Initial Current remains on for the Start Current Time tS and then the Up Slope current ramp will commence. Start Current This parameter operates in 2T GTAW modes 0.5 s 0 s Time tS only and set the time the Start Current is active, after which the Up Slope current ramp will commence. Up Slope This parameter operates in GTAW modes only 0.3 s 0 s Time and is used to set the time for the weld current to ramp up from Initial current to welding current. Welding 150 A 190 A Current A1 (AP) Trough This parameter operates in GTAW Pulse 99 A (66%) 95 A (50%) Current A2 modes only and sets the GTAW TROUGH (AB) current. The lowest point in the pulse is called the Trough. Down Slope This parameter operates in GTAW modes only 1.2 s (5%) 0 s Time and is used to set the time for the weld current to ramp down to the crater current. This control is used to eliminate the crater that can form at the completion of a weld. Crater This parameter operates in GTAW modes 21 A (14%) 5 A (1%) Current AE only. This is the current at the end of the down slope current ramp. The welding current will remain at the Crater Current value until the Crater Current Time has elapsed, at which time the welding current will cease and the unit will enter Post Flow mode. This control is used to eliminate the crater that can form at the completion of a weld. Crater This parameter operates in GTAW modes only 1.8 s 0 s Current Time and is used to set the time for the crater tE current before entering post flow mode. This control is used to eliminate the crater that can form at the completion of a weld. Shielding This parameter operates in GTAW modes only 26% 60% Gas Post- and is used to adjust the post gas flow time Flow time once the arc has extinguished. This control is used to reduce oxidation of the tungsten electrode. AC balance This parameter operates in AC GTAW modes and is used to set the penetration to cleaning action ratio for the AC weld current. Electrode 1.5 to 5.0 mm 2.4 mm 2.4 mm Diameter Pulse This parameter sets the Pulse Frequency 4 Hz 125 Hz Frequency when in GTAW Pulse operating mode. Pulse Duty This parameter sets the percentage “on” time 40% 50% Factor of the Pulse Frequency for welding weld current when in Pulse operating mode

TABLE-US-00013 TABLE 12 Electrode parameters. Parameter Value Diameter 2.4 mm Diameter at tip 1.1 mm Included angle 45° Taper length 2.5 × diameter Tip geometry Pointed Type 2.0% thoriated

[0206] FIG. 9 is photograph of a weld according to an exemplary embodiment. Particularly, FIG. 9 is a photograph of a plan view of the weld W of example E2. The weld profile is visually acceptable, showing no undercut, no concavity and without excess convexity (at most 1 mm proud of the adjacent metal).

[0207] FIG. 10 shows a photograph of a longitudinal cross-section of a weld according to an exemplary embodiment. Particularly, FIG. 10 shows a photograph of the longitudinal cross-section of the weld of example E1, fractured longitudinally, after welding and cooling. Full fusion of the double welded, closed butt joint was achieved, due to sufficient penetration. Rather than fracturing longitudinally through the weld, fracture tends to occur adjacent to the weld, indicating that the welded metal is stronger than the unwelded metal.

GTAW—DC and AC Welding

[0208] FIG. 11A schematically depicts a joint J for a method according to an exemplary embodiment. Particularly, FIG. 11A shows a plan elevation view and a corresponding end elevation view of the joint, having a length of about 1 m.

[0209] GTAW DC and AC welding was performed using a TWECO® ARCMASTER® 301TS, for welding of an anode blade lead alloy 10 (i.e. a first metal), to a lead alloy coated anode bar, comprising a copper bar B having the lead alloy 20 (i.e. a second metal) coated thereon. The first metal 10 has a composition of Pb—1.5 wt. % Sn—0.08 wt. % Ca (referred to as calcium-tin alloy or TC) and a thickness of 6 mm. The second metal 20 has a composition of Pb—5.0 wt. % Sb (referred to as antimonial alloy or 5% ANT) and a thickness of 8 mm at the joint. During welding, some metal tends to flow from the relatively thicker second metal, thereby avoiding use of additional filler, for example. Closed (maximum 0.5 mm gap) square butt joints J between the first metal 10 and the second metal 20 were prepared by machining and the prepared joints J were fused autogenously, by welding from both sides (i.e. double welded, closed butt joints) in a 1G position according to the parameters of Tables 13A to 13C, the parameters having the meanings generally according to Tables 11 and 12 and as described previously. Unless specified otherwise, default parameters were used. Table 13 C summarises results for the welding. No flux was used. Metals having different thicknesses may be welded at corresponding welding currents and/or speeds. For example, relatively thicker metals may be welded at relatively higher welding currents and/or relatively lower welding speeds, while relatively similar metals may be welded at relatively lower welding currents and/or relatively higher welding speeds, for example scaled such as linearly according to thickness. Examples (i.e. TEST PLATE REF) 58-T1, 58-T2 and 58-T3 are for GTAW DC welding of double welded, closed butt joints between two plates of the first metal. The torch was held and moved using a first industrial robot (i.e. automated). Throughput was 15 to 20 such double welded 1 m long welds per hour, with manual set up of joints. Fully automating the welding, using industrial robots, will increase throughput to about 30 to 40 such double welded 1 m long welds per hour. This compares with 3 to 4 such double welded 1 m long welds per hour by manual lead burning by experienced welders. Semi-circular notches are provided at the start end and the stop end of the joint J, to reduce corrosion of the weld, in use. FIG. 11B schematically depicts a joint J for a method according to an exemplary embodiment, generally as described with respect to FIG. 11A, and including cold stops CS1, CS2 provided in contact with the start end and the stop end of the joint J, respectively. In this example, the cold stops CS1, CS2 are earthed discs of copper.

TABLE-US-00014 TABLE 13A Parameters for welding of joints J. START CURRENT SHIELDING AC AS WELDING DOWN GAS PRE- TEST PULSE BALANCE/ RAMP CURRENT SLOPE FLOW PLATE FREQUENCY AC UP A1 TIME TIME SPEED REF (Hz) FREQUENCY (A) (A) (s) (s) (mm s−1) 3107-T1 400 69 150 0 0.5 28 317-T2 400 60 140 0 0.5 28 317-T3 400 50 130 0 0.5 28 317-T4 400 69 150 0 0.5 28 317-T5 400 80 160 0 0.5 28 317-T6 400 75 155 0 0.5 28 18-T1 400 69 150 0 0.5 28 18-T2 400 60 140 0 0.5 28 18-T3 400 50 130 0 0.5 28 18-T4 380 69 150 0 0.5 25 18-T5 380 80 160 0 0.5 25 18-T6 380 75 155 0 0.5 25 18-T7 380 69 150 0 0.5 28 18-T8 350 60 140 0 0.5 28 18-T9 400 69 130 0 0.5 28 18-T10 420 69 150 0 0.5 28 18-T11 400 80 160 0 0.5 28 18T12 400 75 155 0 0.5 28 28-T1 400 69 150 0 0.5 28 28-T2 400 69 150 0 0.5 25 28-T3 400 69 140 0 0.5 22 28-T4 400 69 150 0 0.5 28 58-T1 400 69 140 0 0.5 28 58-T2 400 89 120 0 0.5 28 58-T3 400 89 140 0 0.5 25 68-T1 0 10 89 140 0 0.5 28 68-T2 0 10 89 140 0 0.5 25 68-T3 0 10 89 130 0 0.5 25 68-T4 0 10 89 130 0 0.5 25 68-T5 0 10 89 120 0 0.5 25 68-T6 0 10 89 120 0 0.5 30 78-T1 0 20 120 140 0 0.5 25 78-T2 0 20 130 130 0 0.5 25 78-T3 0 20 120 120 0 0.5 25 78-T4 0 20 110 110 0 0.5 25 78-T5 0 20 100 100 0 0.5 25 78-T6 0 20 140 140 0 0.5 25 88-T1 0 20 120 140 0 0.5 20 88-T2 0 20 130 130 0 0.5 20 88-T3 0 20 120 120 0 0.5 15 88-T4 0 20 110 110 0 0.5 15 88-T5 0 20 100 100 0 0.5 15 88-T6 0 20 140 140 0 0.5 15 88-T7 0 20/40 120 140 0 0.5 20 88-T8 0 20/80 130 140 0 0.5 20 88-T9 0 20/30 120 140 0 0.5 20 88-T10 0 20/30 110 140 0 0.5 20 88-T11 0 20/30 100 140 0 0.5 20 88-T12 0 20/50 140 140 0 0.5 20 228-T1 0 20/40 120 130 0 0.5 25 228-T2 0 20/30 120 130 0 0.5 25 228-T3 0 20/30 120 130 0 0.5 25 228-T4 0 10/30 120 130 0 0.5 25 228-T5 0 30/40 120 140 0 0.5 25 228-T6 0 20/30 120 130 0 0.5 25 228-T7 0 10/30 120 130 0 0.5 25 228-T8 0 20/30 120 130 0 0.5 25 228-T9 0 30/30 120 120 0 0.5 25 228-T10 0 10/30 120 130 0 0.5 25 228-T11 0 10/40 120 140 0 0.5 25 228-T12 0 30/40 120 130 0 0.5 25 278-T1 0 20/40 120 130 0 0.5 25 278-T2 0 20/30 120 130 0 0.5 25 278-T3 0 20/30 120 130 0 0.5 28 278-T4 0 10/30 120 130 0 0.5 25 278-T5 0 30/30 120 140 0 0.5 25 278-T6 0 20/30 120 130 0 0.5 25 288-T7 0 10/30 120 130 0 0.5 25 228-T8 0 20/30 120 130 0 0.5 25 228-T9 0 30/30 120 120 0 0.5 25 228-T10 0 10/30 120 130 0 0.5 25 228-T11 0 10/40 120 130 0 0.5 25 228T12 0 30/30 120 130 0 0.5 25

TABLE-US-00015 TABLE 13B Parameters for welding of joints J (continued) SHIELDING ELECTRODE SLOPE GAS HEIGHT RAMP POST- TEST ABOVE DOWN FLOW PLATE START SURFACE GAS & FLOW TIME NOZZLE TIME REF POSITION (MM) (L MIN.sup.−1) ALIGNMENT (s) ANGLE (s) ALLOYS 3107-T1 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 317-T2 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 317-T3 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 317-T4 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 317-T5 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 317-T6 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T1 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T2 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T3 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T4 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TO 18-T5 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T6 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T7 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T8 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T9 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T10 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18-T11 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 18T12 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% 5% ANT-TC 28-T1 A 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 5 Deg 3.9/61% 5% ANT-TC 28-T2 A 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 5 Deg 3.9/61% 5% ANT-TC 28-T3 A 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 5 Deg 3.9/61% 5% ANT-TC 28-T4 B 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 5 Deg 3.9/61% 5% ANT-TC 58-T1 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% TC-TC 58-T2 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% TC-TC 58-T3 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 5 Deg 3.9/61% TC-TC 68-T1 A 2 MM PURE ARGON 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 68-T2 A 2 MM PURE ARGON 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 68-T3 A 2 MM PURE ARGON 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 68-T4 A 2 MM PURE ARGON 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 68-T5 A 2 MM PURE ARGON 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 68-T6 A 2 MM PURE ARGON 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 78-T1 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 78-T2 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 78-T3 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 78-T4 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 78-T5 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 78-T6 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T1 A 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T2 A 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T3 A 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T4 A 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 VERTICAL 3.9/61% 5% ANT-TO 88-T5 A 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T6 A 2 MM 5% HYD/ARG 15 L UNEVEN 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T7 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T8 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T9 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T10 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T11 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 88-T12 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T1 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T2 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T3 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T4 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T5 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T6 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T7 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T8 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T9 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T10 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T11 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T12 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 278-T1 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 278-T2 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 278-T3 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 278-T4 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 278-T5 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 278-T6 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 288-T7 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T8 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T9 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T10 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T11 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC 228-T12 A 2 MM 5% HYD/ARG 15 L LEVEL 0.0 VERTICAL 3.9/61% 5% ANT-TC

TABLE-US-00016 TABLE 13C Results for welding of joints J. TEST FULL FINISH TENSILE PLATE GENERAL FLAWS & LENGTH POSITION NDT TEST RESULTS/ REF APPEARANCE INCLUSIONS CONSISTENCY CLEANLINESS DETAIL RESULT RESULT COMMENTS 3107-T1 POOR YES POOR OK LONG N/A N/A Weld uneven CRATER 317-T2 POOR YES POOR OK LONG N/A N/A Weld uneven CRATER 317-T3 POOR YES POOR OK LONG N/A N/A Weld uneven CRATER 317-T4 POOR YES POOR OK LONG N/A N/A Weld uneven CRATER 317-T5 POOR YES POOR OK LONG N/A N/A Weld uneven CRATER 317-T6 POOR YES POOR OK LONG N/A N/A Weld uneven CRATER 18-T1 FAILED YES POOR OK LONG N/A N/A Weld uneven CRATER 18-T2 PART OK YES POOR OK LONG N/A N/A Weld uneven CRATER 18-T3 FLAWS YES POOR OK LONG N/A N/A Weld uneven CRATER 18-T4 FLAWS YES POOR OK LONG N/A N/A Weld uneven CRATER 18-T5 POROSITY YES POOR OK LONG N/A N/A Weld uneven CRATER 18-T6 FAILED YES POOR OK LONG N/A N/A Weld uneven CRATER 18-T7 POOR YES BETTER OK LONG N/A N/A Weld Flatter CRATER 18-T8 POOR YES BETTER OK LONG N/A N/A Weld Flatter CRATER 18-T9 POOR YES BETTER OK LONG N/A N/A Weld Flatter CRATER 18-T10 POOR YES BETTER OK LONG N/A N/A Weld Flatter CRATER 18-T11 POOR YES BETTER OK LONG N/A N/A Weld Flatter CRATER 18T12 POOR YES BETTER OK LONG N/A N/A Weld Flatter CRATER 28-T1 POOR YES POOR POOR LONG N/A N/A Weld uneven CRATER 28-T2 SOOTY YES POOR POOR LONG Bend N/A Weld uneven CRATER tested 28-T3 FLAWS YES POOR POOR LONG N/A N/A Weld uneven CRATER 28-T4 POOR YES POOR POOR LONG N/A N/A Weld uneven CRATER 58-T1 GOOD SOME BETTER OK LONG N/A N/A Weld uneven CRATER 58-T2 GOOD SOME BETTER OK LONG N/A N/A Weld uneven CRATER 58-T3 GOOD SOME BETTER OK LONG N/A N/A Weld uneven CRATER 68-T1 MUCH LITTLE BETTER QUITE LESS N/A N/A Weld flatter BETTER SOOTY CRATER 68-T2 MUCH LITTLE BETTER QUITE LESS N/A N/A Weld flatter BETTER SOOTY CRATER 68-T3 MUCH LITTLE BETTER QUITE LESS N/A N/A Weld flatter BETTER SOOTY CRATER 68-T4 MUCH LITTLE BETTER QUITE LESS N/A N/A Weld flatter BETTER SOOTY CRATER 68-T5 MUCH LITTLE BETTER QUITE LESS N/A N/A Weld flatter BETTER SOOTY CRATER 68-T6 MUCH LITTLE BETTER QUITE LESS N/A N/A Weld flatter BETTER SOOTY CRATER 78-T1 MUCH LITTLE BETTER VERY LESS N/A N/A Weld flatter BETTER SOOTY CRATER 78-T2 MUCH LITTLE BETTER VERY LESS N/A N/A Weld flatter BETTER SOOTY CRATER 78-T3 MUCH LITTLE BETTER VERY LESS N/A N/A Weld flatter BETTER SOOTY CRATER 78-T4 MUCH LITTLE BETTER VERY LESS N/A N/A Weld flatter BETTER SOOTY CRATER 78-T5 MUCH LITTLE BETTER VERY LESS N/A N/A Weld flatter BETTER SOOTY CRATER 78-T6 MUCH LITTLE BETTER VERY LESS N/A N/A Weld flatter BETTER SOOTY CRATER 88-T1 BAD BAD BETTER VERY FAILED N/A N/A FAILED SOOTY 88-T2 BAD BAD BETTER VERY FAILED N/A N/A FAILED SOOTY 88-T3 BAD BAD FAILED VERY FAILED FAILED FAILED FAILED SOOTY 88-T4 BAD BAD FAILED VERY FAILED FAILED FAILED FAILED SOOTY 88-T5 BAD BAD FAILED VERY FAILED FAILED FAILED FAILED SOOTY 88-T6 BAD BAD FAILED VERY FAILED FAILED FAILED FAILED SOOTY 88-T7 GOOD FEW GOOD VERY GOOD N/A N/A GOOD FLAT FLAWS SOOTY WELD 88-T8 FAILED FAILED FAILED FAILED FAILED FAILED FAILED FAILED 88-T9 GOOD FEW GOOD VERY GOOD N/A N/A GOOD FLAT FLAWS SOOTY WELD 88-T10 GOOD FEW GOOD VERY GOOD N/A N/A GOOD FLAT FLAWS SOOTY WELD 88-T11 GOOD FEW GOOD VERY GOOD N/A N/A GOOD FLAT FLAWS SOOTY WELD 88-T12 GOOD FEW GOOD VERY GOOD N/A N/A GOOD FLAT FLAWS SOOTY WELD 228-T1 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T2 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T3 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T4 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T5 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T6 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T7 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T8 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T9 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T10 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T11 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 228-T12 GOOD GOOD GOOD VERY GOOD N/A N/A GOOD FLAT SOOTY WELD 278-T1 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 278-T2 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 278-T3 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 278-T4 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 278-T5 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 278-T6 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 288-T7 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 228-T8 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 228-T9 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 228-T10 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD 228-T11 GOOD GOOD GOOD VERY GOOD N/A WITHDRAWN WITHDRAWN SOOTY 228-T12 GOOD GOOD GOOD VERY GOOD N/A AT AMRC GOOD FLAT SOOTY FOR TEST WELD

[0210] Table 13C generally shows that for GTAW welding of the calcium-tin alloy to the antimonial alloy, using the systematically tested parameters shown in Table 13A to 13C, GTAW AC welding is generally preferred.

[0211] Particularly, Examples 3107-T1 to 28-T4 inclusive, for GTAW DC welding of the calcium-tin alloy to the antimonial alloy, generally have poor appearance and poor full-length consistency, while also having inclusions. Weld cleanliness, though, is generally OK.

[0212] In contrast, Examples 58-T1, 58-T2 and 58-T3, for GTAW DC welding of the calcium-tin alloy to the calcium-tin alloy, have good appearance and better full-length consistency, while also having only inclusions. Weld cleanliness is also OK. This is consistent with Example E1 and E2.

[0213] Examples 88-T7 to 228-T12 inclusive (except for Example 88-T8), for GTAW AC welding of the calcium-tin alloy to the antimonial alloy, generally have good appearance and good full-length consistency, while also no inclusions. Weld cleanliness, though, is generally very sooty but the sooty is surface only, not resulting in defects, and readily removed by wiping. The soot arises from aluminium present in the calcium-tin alloy and is not detrimental to weld properties. Rewelding of the weld, after removing the soot, produces a weld having excellent appearance. Table 14 summarises acceptable parameter ranges for GTAW AC welding of the calcium-tin alloy to the antimonial alloy, based on Examples 88-T7 to 228-T12 inclusive (except for Example 88-T8).

TABLE-US-00017 TABLE 14 Acceptable parameter ranges for GTAW AC welding of the calcium- tin alloy to the antimonial alloy. Preferred parameter values for the GTAW AC welding of the calcium-tin alloy to the antimonial alloy, for example having the described geometry, in bold. Parameter Range AC balance 10% to 50%, preferably 10% to 40%, more preferably 10% to 30%, for example 10%, 20% or 30%. 20% gives a good balance between cleanliness and penetration. AC frequency (Hz) 10 Hz to 70 Hz, preferably 20 Hz to 60 Hz, more preferably 30 Hz to 50 Hz, for example 30 Hz, 40 Hz or 50 Hz. 30 Hz is suitable for 6 mm plate and 40 Hz for 8 mm plate. Start current AS (%) 70% to 120%, preferably 80% to 110%, more preferably 90% to 100%, for example 90%, 92.5%, 95%, 97.5% or 100% Welding current 100 A to 170 A, preferably 110 A to 160 A, A1 (A) more preferably 120 A to 150 A, for example 120 A, 130 A, 140 A or 150 A. 130 A is suitable for 6 mm plate and 140 A for 8 mm plate, giving penetration of at least 50%, particularly about 160%. Increasing the current results in burn through while decreasing the current results in insufficient penetration. Ramp down (s) 0 s. Burning through is avoided by limiting heat input at the weld stop. Shielding gas 0 s to 2 s, preferably 0. 25 s to 1 s, for pre-flow time (s) example 0.5 s Speed (mm s.sup.−1) 10 mm s.sup.−1 to 40 mm s.sup.−1, preferably 15 mm s.sup.−1 to 35 mm s.sup.−1, more preferably 20 mm s.sup.−1 to 30 mm s.sup.−1, for example 20 mm s.sup.−1, 25 mm s.sup.−1, 28 mm s.sup.−1 or 30 mm s.sup.−1 Start position A i.e. about 5 mm from the end of the joint thereby providing penetration to the end of the joint. Starting closer to the end of the joint may result in burn through while starting further from the end of the joint may result in insufficient penetration to the end of the joint. Electrode height 1.0 mm to 6.0 mm, preferably 1.5 mm to 5.0 above surface (mm) mm, more preferably 2.0 mm to 4.0 mm, most preferably 3.0 mm to 4.0 mm, for example 3.0 mm, 3.25 mm, 3.5 mm, 3.75 mm or 4.0 mm. Higher gas flows at lower heights may blow out the plasma. Gas Specshield 95% argon, 5% hydrogen. Gas flow (L min.sup.−1) 2.5 L min.sup.−1 to 25 L min.sup.−1, preferably 5 L min.sup.−1 to 20 L min.sup.−1, more preferably 7.5 L min-.sup.1 to 17.5 L min.sup.−1, for example 10 L min.sup.-1. Higher gas flows at lower heights may blow out the plasma. Alignment of the Level or step e.g. 1 mm to 2 mm. The molten surfaces of the plates step flows into the weld, providing filler metal, if required Down slope time (s) 0 s to 2 s, preferably 0 s to 1 s, for example 0 s, 0.25 s, 0.5 s, 0.75 s or 1 s. Burning through is avoided by limiting heat input at the weld stop. Nozzle Angle Vertical or slightly trailing around 87 degrees. Improved weld appearance while allowing for monitoring during welding. Shielding gas 0.5 s to 10 s, preferably 1 to 8 s, more post-flow time (s) preferably 1 to 6 s, for example 1, 1.5, 2, 3, 4, 5 or 6 s. The weld metal solidifies rapidly such that lengthy shielding gas post-flow is not required.

Mechanical Testing

[0214] Examples 278-T1 to 228-T12 inclusive (except for Example 228-T11) were subject to mechanical testing, as described below.

[0215] Tension test specimens were prepared conforming with ASME IBPVC.IX-2015 (see QW-151). Three (3) batches of five (5) test specimens were prepared from:

a. Batch of six (6) of parent material antimonial alloy;
b. Batch of six (6) of parent material calcium-tin alloy; and
c. Batch of six (6) welded material of these two materials.

[0216] The tension test specimens were tested conforming with ASME IBPVC.IX-2015 (see QW-152). Photographs showing respective failure modes of the tension test specimens were obtained.

Calcium-Tin Alloy Test Specimens

[0217] FIG. 12 shows a graph of tensile stress as a function of displacement for the calcium-tin alloy tension test specimens. Table 15 summarises dimensions and tension test results for the calcium-tin alloy tension test specimens. The mean ultimate tensile strength (UTS) was 48.1 MPa, having a standard deviation of 0.84 MPa. Elongation to failure was 18.3%, having a standard deviation of 4.6%.

TABLE-US-00018 TABLE 15 Dimensions and tension test results for calcium-tin alloy tension test specimens. Original Final Overall Gauge Gauge Test Length Width Thickness CSA Load UTS Length Length Elongation specimen No. (mm) (mm) (mm) (mm.sup.2) (N) (MPa) (mm) (mm) (%) AS4528-TC-01 201.58 12.57 6.28 79 3850 48.8 50.11 60.12 19.98 AS4528-TC-02 201.21 12.60 6.23 78 3680 46.9 50.09 56.07 11.94 AS4528-TC-03 200.45 12.47 6.24 78 3720 47.8 50.16 60.92 21.45 AS4528-TC-04 201.29 12.55 6.33 79 3780 47.6 50.11 61.39 22.51 AS4528-TC-05 200.86 12.52 6.24 78 3840 49.2 50.08 56.52 12.86 AS4528-TC-06 201.73 12.52 6.24 78 3790 48.5 50.17 60.66 20.91 Mean 48.1 18.3  (Standard deviation) (0.84) (4.6)

[0218] FIG. 15 shows photographs of the calcium-tin alloy tension test specimens, after testing.

Antimonial Alloy Test Specimens

[0219] FIG. 13 shows a graph of tensile stress as a function of displacement for the antimonial alloy tension test specimens. Table 16 summarises dimensions and tension test results for antimonial alloy tension test specimens. The mean ultimate tensile strength (UTS) was 51.4 MPa, having a standard deviation of 7.8 MPa (i.e. greater variability than for the calcium-tin alloy tension test specimens). Elongation to failure was 7.2%, having a standard deviation of 2.9% (i.e. relatively less elongation but also less variability than for the calcium-tin alloy tension test specimens).

TABLE-US-00019 TABLE 16 Dimensions and tension test results for antimonial alloy tension test specimens. Original Final Gauge Gauge Test Length Width Thickness CSA Load UTS Length Length Elongation specimen No. (mm) (mm) (mm) (mm.sup.2) (N) (MPa) (mm) (mm) (%) AS4528-AN-01 202.60 12.43 8.36 104 6310 60.7 50.07 54.08 8.01 AS4528-AN-02 201.50 12.77 7.38 94 4680 49.7 50.04 55.62 11.15 AS4528-AN-03 199.70 12.70 7.64 97 4420 45.6 50.13 55.16 10.03 AS4528-AN-04 201.13 12.35 8.31 103 6310 61.5 50.04 52.46 4.84 AS4528-AN-05 201.62 12.56 8.24 103 4560 44.1 50.16 52.56 4.78 AS4528-AN-06 201.06 12.54 7.44 93 4350 46.6 50.08 52.41 4.65 Mean 51.4 7.2 (Standard deviation) (7.8) (2.9)

[0220] Lead alloys including antimony are generally more brittle than other lead alloys, hence resulting in the greater variability of the UTS and lower elongation than for the calcium-tin alloy tension test specimens.

[0221] FIG. 16 shows photographs of the antimonial alloy tension test specimens, after testing.

Welded Specimens

[0222] FIG. 14 shows a graph of tensile stress as a function of displacement of welds according to an exemplary embodiment of the first metal 10 of FIG. 12 and the second metal 20 of FIG. 13. Table 17 summarises dimensions and tension test results for the welded tension test specimens. The mean ultimate tensile strength (UTS) was 41.1 MPa, having a standard deviation of 2.0 MPa (i.e. lower than for the calcium-tin alloy tension test specimens and for the antimony alloy tension test specimens). Elongation to failure was 7.4%, having a standard deviation of 1.2% (i.e. about the same elongation as for the antimony alloy tension test specimens but also less variability).

TABLE-US-00020 TABLE 17 Dimensions and tension test results for welded tension test specimens. Original Final Overall Gauge Gauge Test Length Width Thickness CSA Load UTS Length Length Elongation specimen No. (mm) (mm) (mm) (mm.sup.2) (N) (MPa) (mm) (mm) (%) AS4528-WS-01 196.54 12.59 6.32 80 3190 40.1 50.20 53.62 6.81 AS4528-WS-02 197.86 12.54 6.25 78 3190 40.7 50.23 54.25 8.00 AS4528-WS-03 196.13 12.58 6.32 80 3090 38.9 50.11 53.78 7.32 AS4528-WS-04 195.66 12.60 6.37 80 3500 43.6 50.23 52.93 5.38 AS4528-WS-05 196.34 12.53 6.26 78 3130 39.9 50.16 54.26 8.17 AS4528-WS-06 194.46 12.51 6.27 78 3430 43.7 50.17 54.53 8.69 Mean 41.1 7.4 (Standard deviation) (2.0) (1.2)

[0223] Failure of the welded tension test specimens was in the antimony alloy, adjacent to the weld. Nevertheless, the tension test properties of the weld metal are comparable with that of the antimony alloy and meet acceptance criteria for lead anodes for electrowinning, for example. FIG. 17 shows photographs of the weld tension test specimens, after testing.

[0224] Although a preferred embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above.

PAW—DC Welding

[0225] PAW DC welding was performed using a Fronius® PlasmaModule 10®, for welding of lead alloy sheet for guttering and downpipes, for example, having a nominal thickness of 2 mm. The first metal 10 has a composition of Pb—1.5 wt. % Sn—0.7 wt. % Ca (referred to as calcium-tin alloy or TC) and a thickness of 2 mm. The second metal 20 has a composition of Pb—4.0 wt. % Sb (referred to as antimonial alloy or 4% ANT) and a thickness of 2 mm. Closed (maximum 0.2 mm gap) square butt joints J between the first metal 10 and the second metal 20 were prepared and the prepared joints J were fused autogenously, by welding from one side (i.e. single welded, closed butt joints) in a 1G position. An earthing electrode was positioned at the underside of the joint J, to control direction of the plasma arc and to provide a backing strip. PAW DC was performed at a speed of 3 mm s.sup.−1 at a pulsed current in a range from 4 to 10 A. Unless specified otherwise, default parameters were used. Pureshield Argon at a flow rate of 0.6 to 1 L min.sup.−1 was used, with the gas nozzle about 2 to 3 mm away from the metal. Electrode diameter was 1.5 mm.

[0226] PAW DC welding at similar conditions performed successfully also for lead alloys having a thickness in a range from 2 to 12 mm (double sided for thicknesses greater than about 6 mm).

Attention

[0227] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0228] All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at most some of such features and/or steps are mutually exclusive.

[0229] Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0230] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.