TITANIUM-CONTAINING ZINC WROUGHT ALLOY

Abstract

The present invention relates to a zinc wrought alloy with improved machinability as compared to known wrought alloys, as well as semifinished products, forgings, turned parts, locks, screw connections, locking cylinders, sleeves, fittings, pressed parts, pneumatic parts, hydraulic parts, mountings, valves and ball valves that comprise a zinc wrought alloy according to the invention.

Claims

1. A zinc wrought alloy having an Al content of from 5% by weight to 18% by weight, a Cu content of from 0.1% by weight to 4% by weight, an Mg content of from 0.001% by weight to 0.05% by weight, a Ti content of from 0.01% by weight to 1% by weight, wherein Zn is the balance to 100%, and wherein the alloy may contain impurities at a proportion of 0.07% by weight or less.

2. The zinc wrought alloy according to claim 1, characterized in that lead is not alloyed.

3. The zinc wrought alloy according to claim 1, characterized in that the content of Al is from 8% to 16% by weight.

4. The zinc wrought alloy according to claim 1, characterized in that the content of Ti is from 0.03% to 1% by weight.

5. The zinc wrought alloy according to claim 1, characterized in that the content of Cu is from 0.1% to 2.5% by weight.

6. The zinc wrought alloy according to claim 1, characterized in that the content of Mg is from 0.003% by weight to 0.05% by weight.

7. The zinc wrought alloy according to claim 1, characterized by containing silicon as an impurity.

8. The zinc wrought alloy according to claim 1, having an Al content from 5% to 9% by weight, a Cu content from 0.5% to 2.5% by weight, a magnesium content from 0.003% to 0.05% by weight, a titanium content from 0.05% to 1% by weight, with zinc as the balance to reach 100% by weight.

9. The zinc wrought alloy according to claim 1, having an Al content from 5% to 9% by weight, a Cu content from 0.5% to 1.5% by weight, an Mg content from 0.003% to 0.05% by weight, a Ti content from 0.05% to 1% by weight, with zinc as the balance to reach 100% by weight.

10. The zinc wrought alloy according to claim 1, having an Al content from 10% to 12% by weight, a Cu content from 0.5% to 2.5% by weight, an Mg content from 0.003% to 0.05% by weight, a Ti content from 0.05% to 1% by weight, with zinc as the balance to reach 100% by weight.

11. The zinc wrought alloy according to claim 1, having an Al content from 10% to 12% by weight, a Cu content from 0.5% to 1.5% by weight, an Mg content from 0.003% to 0.05% by weight, a Ti content from 0.05% to 1% by weight, with zinc as the balance to reach 100% by weight.

12. The zinc wrought alloy according to claim 1, having an Al content from 14% to 16% by weight, a Cu content from 0.5% to 2.5% by weight, an Mg content from 0.003% to 0.05% by weight, a Ti content from 0.05% to 1% by weight, with zinc as the balance to reach 100% by weight.

13. The zinc wrought alloy according to claim 1, having an Al content from 14% to 16% by weight, a Cu content from 0.5% to 1.5% by weight, an Mg content from 0.003% to 0.05% by weight, a Ti content from 0.05% to 1% by weight, with zinc as the balance to reach 100% by weight.

14. The zinc wrought alloy according to claim 1, having an Al content from 16% to 18% by weight, a Cu content from 0.5% to 2.5% by weight, a magnesium content from 0.001% to 0.05% by weight, a titanium content from 0.05% to 1% by weight, with zinc as the balance to reach 100% by weight.

15. The zinc wrought alloy according to claim 1, having an Al content from 16% to 18% by weight, a Cu content from 0.5% to 1.5% by weight, a magnesium content from 0.001% to 0.05% by weight, a titanium content from 0.05% to 1% by weight, with zinc as the balance to reach 100% by weight.

16. An object of manufacture comprising the zinc wrought alloy according to claim 1, the object of manufacture being a semifinished product and/or article.

17. The object of manufacture according to claim 16, wherein said semifinished product is a billet, an extruded section, a drawn section, a wire, a strip, a powder, or a pressure die-cast alloy.

18. The object of manufacture according to claim 16, wherein said article is a forging, turned part, lock, screw connection, locking cylinder, sleeve, fitting, pressed part, pneumatic part, hydraulic part, mounting, valve or ball valve.

19. The object of manufacture of claim 16 being one of semifinished products, forgings, turned parts, locks, screw connections, locking cylinders, sleeves, fittings, pressed parts, pneumatic parts, hydraulic parts, mountings, valves and ball valves.

20. A process for preparing and/or reshaping and/or processing semifinished products, forgings, turned parts, locks, screw connections, locking cylinders, sleeves, fittings, pressed parts, pneumatic parts, hydraulic parts, mountings, valves and ball valves according to claim 19 by cold or hot reshaping.

21. The process according to claim 20, characterized in that said processing includes processing by forging or machining, especially turning, drilling, milling, broaching, sawing, grinding or honing.

Description

EXAMPLES

[0040] The zinc wrought alloy according to the invention was compared with the following materials:

TABLE-US-00001 TABLE 1 Comparative material (comparative experiments) Properties Unit Zinc alloy Aluminum content % by weight 13-25 Copper content % by weight 0.2-3.5 Magnesium content % by weight <0.1 Lead content % by weight <0.004 Zinc content % by weight balance Tensile strength MPa 412 Yield strength MPa 374 Brinell hardness HB (2.5/62.5) 128 Creep tendency (A.sub.f.sup.RT.sub.100.1) % 0.05

[0041] A zinc wrought alloy as described in EP 2 675 971 was used as a comparative material (information in column “zinc alloy” in Table 1).

[0042] The qualification of the zinc wrought alloy according to the invention is based on four methods delimited from one another, which are set forth in the following. They are the basis of the determination of the claimed composition boundaries. If one of the compositions showed defects, this led to exclusion.

[0043] From a zinc alloy as described in Table 1 as well as from the following alloys according to the invention, billets having a diameter of 135 mm were prepared, which served as a starting point for the qualification:

TABLE-US-00002 TABLE 2 Alloys according to the invention Specimen Specimen Specimen Specimen Components Unit 1 2 3 4 Aluminum % by weight 5-9 10-12 14-16 16-18 Copper % by weight 0.5-2.5 0.5-1.5 0.5-1.5 0.5-2.5 Magnesium % by weight 0.003-0.05  0.003-0.05  0.003-0.05  0.003-0.05  Titanium % by weight 0.05-1   0.05-1   0.05-1   0.05-1  

[0044] Both the billets/alloys according to the invention and the comparative alloys/billets were analyzed by the following methods relating to different mechanical properties as well as machinability (qualification):

[0045] Method 1 (Reshaping Method):

[0046] The billet was heated at 250° C. in an oven. Thereafter, the billet was extruded into a round section. Further, the extruded round rod was drawn to a final dimension of 26 mm. The testing requirements were considered to be met if no signs of surface cracks or blisters have formed.

[0047] Method 2 (Tensile Test):

[0048] As the second method, a tensile test was performed. The exact realization, the definition of the measurable characteristics and the specimen shape are defined in DIN EN ISO 6892-1:2017.

[0049] A section of the drawn round rod having a diameter of 26 mm was lathe-turned into a specimen for tensile testing as shown in FIG. 1. It was clamped into the tensile testing machine and exposed to a uniaxial load until the specimen broke. Meanwhile, the force, width and length were continuously measured electronically, whereby the stress-strain curve (FIG. 2) could be determined.

[0050] Method 3 (Creep Tendency):

[0051] Further, the creep tendency or creep strength according to DIN EN ISO 204:2009 was tested as a third method. A specimen as shown in FIG. 1 was subjected to a long-acting uniaxial tensile force at a constant test temperature. In this case, the specimen was loaded constantly with 100 MPa at room temperature. Meanwhile, the axial strain was measured.

[0052] Method 4 (Shape of Chip):

[0053] In the fourth method, a section of the drawn round rod was clamped into a turning machine. A turned part having rotational symmetry with five recessed grooves having widths of 3 mm and depths of 3 mm was prepared therefrom. The testing requirements were considered to be met if the chip shape corresponds to industrial custom.

[0054] Results:

[0055] At first, the different alloy ranges were tested with respect to aluminum content, because the latter represents the major alloy component. In the following Table 3, the mechanical characteristics of the alloys according to the invention (samples 1 to 4 according to Table 2) are shown. They were determined by the above described methods 2 and 3.

TABLE-US-00003 TABLE 3 Mechanical characteristics of the alloys according to the invention (methods 2 and 3) Specimen Specimen Specimen Specimen Properties Unit 1 2 3 4 Tensile MPa 397 392 411 422 strength Yield MPa 322 347 372 381 strength (R.sub.p0.2) Brinell HB 136 128 132 133 hardness (2.5/62.5) Creep % 0.01 0.04 0.05 0.05 tendency (A.sub.f.sup.RT.sub.100.1)

[0056] Surprisingly, the selective alloying with titanium did not have a negative impact on the mechanical characteristics. In the comparison with the comparative material (zinc alloy from Table 1), no significant differences could be seen.

[0057] Results of Method 4 (Shapes of Chips)—Specimens 1, 2, 3 and 4:

[0058] a) Specimens 1 to 4 According to the Invention were Processed as Described Above Under Method 4 with the Following Parameters:

TABLE-US-00004 TABLE 4 Machining parameters (high cutting speed) Cutting speed [m/min] Feed speed [mm/U] 210 0.05

[0059] Photographs of the chip shapes and the specimens that were processed are shown in FIG. 3. From the results, it can be readily seen that all ranges of the present invention showed a good machinability. This was shown by the spiral chips produced by each of the four specimens. Spiral chips are advantageous, in particular, for automated production processes. The high cutting speed achieved increases efficiency and is thus also very advantageous.

[0060] b) Specimens 1 to 4 According to the Invention were Processed as Described Above Under Method 4 with the Following Parameters:

TABLE-US-00005 TABLE 5 Machining parameters (medium cutting speed) Cutting speed [m/min] Feed speed [mm/U] 90 0.15

[0061] Photographs of the chip shapes and the specimens that were processed are shown in FIG. 4. At a medium cutting speed, all the specimens showed a good machinability. Both spiral chips and conical helical chips were produced.

[0062] Other alloys according to the invention—specimens 3a to 3d

[0063] Further, different titanium contents were tested for determining a preferred composition by means of specimen 3:

TABLE-US-00006 TABLE 6 Specimens with different titanium contents (alloy according to the invention): Specimen Specimen Specimen Specimen Specimen Components Unit 3a 3 3b 3c 3d Aluminum % by weight 14-16  14-16  14-16  14-16 14-16 Copper % by weight 0.5-1.5  0.5-1.5  0.5-1.5  0.5-1.5 0.5-1.5 Magnesium % by weight 0.003-0.05  0.003-0.05 0.003-0.05 0.003-0.05 0.003-0.05  Titanium % by weight 0.01-0.05 0.06-0.1 0.15-0.2 0.25-0.4 0.8-1.0

[0064] Results of Methods 2 and 3—Specimens 3a, 3b and 3c:

[0065] The following Table 7 shows the results of the mechanical properties of the specimens (results of methods 2 and 3).

TABLE-US-00007 TABLE 7 Mechanical properties of the specimens with different titanium contents (methods 2 and 3) Specimen Specimen Specimen Specimen Properties Unit 3a 3 3b 3c Tensile MPa 401 411 409 410 strength Yield MPa 365 372 370 369 strength (R.sub.p0.2) Brinell HB 129 132 133 131 hardness (2.5/62.5) Creep % 0.03 0.05 0.04 0.04 tendency (A.sub.f.sup.RT.sub.100.1)

[0066] Surprisingly, the titanium content in different amounts does not show any negative impact on the mechanical properties.

[0067] Results of Method 4 (Shapes of Chips)—Specimens 3a, 3b, 3c and 3d:

[0068] The machining parameters of Tables 4 and 5 remained identical. Photographs of the chip shapes and the specimens that were processed are shown in FIGS. 5 (parameters according to Table 4) and 6 (parameters according to Table 5).

[0069] In the comparison in FIG. 5, it can be readily seen that the machining properties were improved as the titanium content increased. The chips achieved good chip shapes, which clearly enhances productivity in the processing in a turning machine. These include, but are not limited to, short helical chips, spiral chips, and long helical chips. Further, it was found that the alloy having a Ti content of 0.1% by weight is particularly process-safe. It constantly produced long helical chips, while the chip length varied more with the other titanium contents.

[0070] The results from FIG. 6 are similar to those of FIG. 5 and also show good machining properties. Short helical chips were produced in most cases.

[0071] In the last step, the alloy 3 according to the invention was compared with the comparative material from EP 2 657 971.

[0072] Results of Method 4 (Shapes of Chips)—Specimen 3 vs. Zinc Alloy According to EP 2 675 971:

[0073] The machining parameters of Tables 4 and 5 remained identical. Photographs of the chip shapes and the specimen that was processed are shown in FIGS. 7 (parameters according to Table 4) and 8 (parameters according to Table 5).

[0074] In the comparison in FIG. 7, the extent of improvement of the chip shapes by the zinc alloy according to the invention can be readily seen. At a cutting speed of 210 m/min, long entangled chips were produced with the zinc alloy from the prior art (as mentioned in EP 2 675 971, Comparative Example). Surprisingly, a clearly better chip shape could be achieved by selectively alloying with titanium. Such chip shape of the inventive alloys are ideal for processing in a turning machine, avoiding risks and disruptions in the cutting process, such as the chip becoming wound up around the workpiece or the tool. A high cutting speed is also desirable, and is also possible with the alloy according to the invention, because the process speed of the semifinished products in the turning machine can be increased. Surprisingly, the high cutting speed can be achieved by the present invention.

[0075] Also at lower cutting speeds, as shown in FIG. 8, the zinc alloy according to the invention achieved chip shapes that are better for turning processing as compared to those obtained with the comparative zinc alloy as described in EP 2 675 971.