Hybrid electroslag cladding

Abstract

A hybrid electroslag cladding method includes the steps of: providing a workpiece (6) to be cladded; guiding a strip electrode (4) onto the surface of the workpiece (6); cladding the strip electrode (4) onto the surface of the workpiece (6) using electroslag cladding; guiding a metal cored hybrid electroslag cladding wire (7) into the weld puddle (9) of the strip electrode (4) for controlling the chemical composition of the cladding.

Claims

1. A hybrid electroslag cladding method, the method comprising: providing a workpiece to be cladded; guiding a strip electrode onto a surface of the workpiece; cladding the strip electrode onto the surface of the workpiece using electroslag cladding; and guiding a metal cored hybrid electroslag cladding wire into a weld puddle of the strip electrode for controlling a chemical composition of the cladding, and for a second workpiece requiring stainless steel cladding with a different cladding composition than the workpiece, selecting a second metal cored hybrid electroslag cladding wire for controlling a chemical composition of the cladding of the second workpiece, wherein the chemical composition of the metal cored hybrid electroslag cladding wire differs from the chemical composition of the second metal cored hybrid electroslag cladding wire.

2. The method of claim 1, further comprising: using a flux of a given composition for the workpiece and the second workpiece.

3. The method of claim 1, further comprising: controlling at least one of a stickout length of the metal cored hybrid electroslag cladding wire, a feed speed of the strip electrode, and a feed speed of the metal cored hybrid electroslag cladding wire.

4. The method of claim 3, wherein the feed speed of the metal cored hybrid electroslag cladding wire is changed if a change of the feed speed of the strip electrode is detected.

5. The method of claim 1, wherein the metal cored hybrid electroslag cladding wire is heated.

6. The method of claim 1, wherein the metal cored hybrid electroslag cladding wire includes a stainless steel base sheath and a metal powder flux within the stainless steel base sheath, and wherein the wire has a composition that is defined by WIRE 308L, WIRE 347, WIRE 316L, or WIRE 317L.

7. The method of claim 6, wherein for the metal cored hybrid electroslag cladding wire an upper limit of at least one element in the composition is one of 5%, 10% or 20% lower than that defined in the respective WIRE 308L, WIRE 347, WIRE 316L, or WIRE 317L.

8. The method of claim 6, wherein for the metal cored hybrid electroslag cladding wire a lower limit of at least one element in the composition is one of 5%, 10% or 20% higher than that defined in the respective WIRE 308L, WIRE 347, WIRE 316L, or WIRE 317L.

9. A hybrid electroslag cladding system, comprising: a cladding head for guiding a strip electrode onto a surface of a workpiece to be cladded with the strip electrode; a cladding power supply for providing power to the strip electrode for arcless deposition onto the surface of the workpiece; and a flux feeder for at least one of depositing flux on the strip electrode and depositing flux adjacent the strip electrode, wherein the cladding head is configured to guide a metal cored hybrid electroslag cladding wire into a weld puddle of the strip electrode, wherein the metal cored hybrid electroslag cladding wire has a composition that is defined by one of WIRE 625, WIRE 600, WIRE 825, WIRE 400, WIRE 308L, WIRE 347, WIRE 316L, or WIRE 317L, and wherein the hybrid electroslag cladding system further comprises a steering magnet disposed adjacent the strip electrode for steering the weld puddle magnetically.

10. The system of claim 9, further comprising: a hot wire power supply for heating the metal cored hybrid electroslag cladding wire; and a controller for controlling at least one of a temperature of the metal cored hybrid electroslag cladding wire according to a desired deposition rate, a stickout length of at least one of the metal cored hybrid electroslag cladding wire the and the strip electrode, a feed speed of the strip electrode, and a feed speed of the metal cored hybrid electroslag cladding wire.

11. The system of claim 9, wherein an angle between at least one of the strip electrode and the metal cored hybrid electroslag cladding wire and the surface of the workpiece is adjustable.

12. The system of claim 9, wherein the cladding head guides at least two metal cored hybrid electroslag cladding wires disposed adjacent to each other into the weld puddle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a hybrid cladding system.

(2) FIG. 2 shows a cladding head in (a) a 3D-view, (b) a left view, (c) a front view, (d) a right view, (e) a rear view, and (f) an enlarged detail from the encircled region of FIG. 2(a).

(3) FIGS. 3 (a), (b), (c) illustrate embodiments with one, two and four metal cored hybrid cladding wires, in a view along the arrow 11 of FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS

(4) Embodiments of the inventive systems, methods and wires are discussed in more detail.

(5) System

(6) FIG. 1 illustrates a cladding system 1 having a flux feeder 2 and a cladding head 3 which guides both, a strip electrode 4 powered by a cladding power supply 5 onto a surface of a workpiece 6, as well as a metal cored hybrid cladding wire 7 heated by a hot wire power supply 8 into the weld puddle 9 of the strip electrode 4.

(7) The strip electrode 4 covered by flux 10 is deposited onto the surface of the workpiece 6 by means of an arcless electroslag process for cladding the workpiece 6 while the cladding 3 head moves along the workpiece 6 in the direction of arrow 11. Both the strip electrode 4 and the surface of the workpiece 6 melt and form the weld puddle 9 which solidifies after a period of time. Prior to solidification, the metal cored hybrid cladding wire 7 is fed into the weld puddle 9. The wire 7 melts and mixes with the weld puddle 9, controlling the chemical composition of the resulting cladding layer 12.

(8) A controller 13 for controlling the heat of the metal cored hybrid cladding wire 7 according to a desired deposition rate, the movement of the cladding head 3, and the cladding power supply 5, is preferably provided. The controller 13 may be connected to the powers supplies 5, 8 and the welding head 3 as well as strip and wire feeders (not depicted) by wire connection, via a network and/or wirelessly.

(9) The flux feeder 2 is preferably attached to the cladding head 3 and filled with flux for electroslag cladding, see FIG. 2 showing an embodiment with two metal cored hybrid cladding wires 7.

(10) In a preferred embodiment, the cladding head 3 is adapted to guide the strip electrode 4 about vertically onto the surface of the workpiece 6, see in particular FIG. 2(d), and the metal cored hybrid cladding wire 7 is guided downstream of movement arrow 11 into the weld puddle.

(11) A magnetic steering device 14, here comprising two steering magnets 15 adjacent either side of the strip electrode 4, may be provided for steering the weld puddle magnetically. This allows a precise control of the weld puddle, in particular width.

(12) Mechanisms 16 may be provided on the cladding head for adjustment the angle between the strip electrode 4, the metal cored hybrid cladding wire 7, and/or the surface of the workpiece 6, see in particular FIG. 2 (d).

(13) A strip wire feeder 17 and a metal cored hybrid cladding wire feeder 18 are preferably attached on or provided adjacent the cladding head.

(14) The wire 7 is preferably positioned at the centre of the strip electrode, see FIG. 3(a). More than one wire 7 can be used, see FIGS. 3(b), 3(c). If more wires 7 are used, they are preferably identical. However, they may be of different compositions and/or diameters. Ideally, the wires 7 are spaced equidistant across the width of the strip electrode 4 in order to ensure a homogeneous composition of the cladding layer 12, however, they may also be spaced at different distances, e.g. closer towards the edges, see FIG. 3(c), or centered as in FIG. 2(c).

(15) Wires

(16) In the stainless steel based aspect of the invention, the following metal cored hybrid electroslag cladding wires are used (all figures are wt %, bal=balance):

(17) Wire 308L

(18) TABLE-US-00001 All other C Mn Si S P Cr Ni Mo Cu Fe elements Min 0 0.5 0 0 0 18.0 9.0 0 0 0 0 Max 0.03 2.50 1.0 0.015 0.030 23.0 13.0 0.85 0.75 Bal 0.50

(19) Wire 347

(20) TABLE-US-00002 All other C Mn Si S P Cr Ni Mo Nb Cu Fe elements Min 0 0 0 0 0 18.0 9.0 0 1.0 0 0 0 Max 0.08 2.50 1.0 0.015 0.030 23.0 13.0 0.75 5.0 0.75 Bal 0.50

(21) Wire 316L

(22) TABLE-US-00003 All other C Mn Si S P Cr Ni Mo Cu Fe elements Min 0 0 0 0 0 17.0 16.0 7.0 0 0 0 Max 0.04 2.50 1.0 0.015 0.030 22.0 21.0 11.0 0.75 Bal 0.50

(23) Wire 317L

(24) TABLE-US-00004 All other C Mn Si S P Cr Ni Mo Cu Fe elements Min 0 0 0 0 0 18.0 18.0 10.0 0 0 0 Max 0.04 2.50 1.0 0.015 0.030 23.0 22.0 15.0 0.75 Bal 0.50

(25) In the nickel based aspect of the invention, the following metal cored hybrid electroslag cladding wires are used (all figures are wt %):

(26) Wire 625

(27) TABLE-US-00005 C Mn Si S P Cr Ni Mo Nb Cu Al Ti Fe Min 0 0 0 0 0 22.0 50 8.0 3.5 0 0 0 0 Max 0.05 0.50 0.50 0.015 0.015 27.0 bal 14.0 6.5 0.50 0.50 0.50 2.0 All other elements <0.50%

(28) Wire 600

(29) TABLE-US-00006 C Mn Si S P Cr Ni Nb Cu Ti Fe Min 0 2.0 0 0 0 21.0 67 2.0 0 0.2 0 Max 0.05 5.0 0.50 0.015 0.020 26.0 bal 5.0 0.50 0.8 3.0 All other elements <0.50%

(30) Wire 825

(31) TABLE-US-00007 C Mn Si S P Cr Ni Mo Cu Al Ti Fe Min 0 0 0 0 0 24.0 46 2.0 1.0 0 0.8 0 Max 0.05 1.0 0.50 0.015 0.020 27.0 52 14.0 4.0 0.20 1.6 Bal All other elements <0.50%

(32) Wire 400

(33) TABLE-US-00008 C Mn Si S P Ni Cu Al Ti Fe Min 0 0 0 0 0 62.0 28.0 0 0 0 Max 0.15 4.0 1.2 0.015 0.020 68.0 36.0 0.75 1.2 2.5 All other elements <0.50%

(34) Method

(35) The cladding system is operated according to the following method. First, a workpiece to be cladded is provided. Then, a strip electrode is guided onto the surface of the workpiece. The strip electrode is cladded onto the surface of the workpiece using electroslag cladding, while a metal cored hybrid cladding wire is heated and guided into the weld puddle of the strip electrode.

(36) When cladding nickel based workpieces, a combination of a strip electrode and metal cored hybrid electroslag cladding wire is used to obtain the desired final chemistry of the cladding. When cladding stainless steel based workpieces, a standard strip electrode can be used for different workpiece compositions, and only the metal cored hybrid electroslag cladding wire will be varied to achieve the desired cladding composition. Preferred wire compositions are specified in the preceding section.

(37) It is preferred to make the following combinations:

(38) TABLE-US-00009 metal cored hy- brid electroslag Nickel Base cladding wire strip electrode Flux Alloy 625 Wire 625 Typical 625 Strip Flux A Alloy 600 Wire 600 Typical 600 Strip Flux A Alloy 825 Wire 825 Typical 825 Strip Flux A Alloy 400 Wire 400 Typical 400 Strip Flux A

(39) The preferred Flux A is an Electro Slag High speed flux with Al.sub.2O.sub.3+CaF.sub.2>73 wt % without any intended metallic addition. Other flux compositions may work as well, but with inferior performance. The strip is preferably a standard strip.

(40) TABLE-US-00010 metal cored hy- Stainless Steel brid electroslag Base cladding wire strip electrode Flux 308L Wire 308L Typical 18Cr8Ni Flux B Strip 347 Wire 347 Typical 18Cr8Ni Flux B Strip 316L Wire 316L Typical 18Cr8Ni Flux B Strip 317L Wire 317L Typical 18Cr8Ni Flux B Strip

(41) The preferred Flux B is an Electro Slag High speed flux with Al.sub.2O.sub.3+CaF.sub.2>81 wt % without any intended metallic addition. Other flux compositions may work as well, but with inferior performance. The strip is preferably a typical 18Cr-8Ni Strip.

(42) The speed of movement of the cladding head 3 is preferably about 27 cm/min for Ni alloys and about 33 cm/min for stainless steel alloys, and the cladding layer thickness is preferably about 5 mm.

Preferred Embodiment

(43) Various different embodiments and individual aspects of the invention have been described above. They may be combined in any way. In a preferred embodiment, the invention provides a cladding head in which the strip electrode is fed essentially vertically onto the workpiece and the metal cored hybrid wire is fed in an adjustable angle relative thereto as indicated in FIG. 2. A magnetic steering device is provided in the preferred embodiment as are a PLC controller, configured to control stick out length of the strip and/or metal cored hybrid electroslag wire(s) and the feed speeds of the metal cored hybrid electroslag wire(s) and the strip electrode, as well as the heat provided to the metal cored hybrid electroslag wire(s). In the preferred embodiment, a single layer of cladding is deposited on the workpiece with a high speed and homogenous and uniform cladding chemistry according to the required grade.

Further Embodiments

(44) Although only a few embodiments of this invention have been described above, it should be appreciated that many modifications can be made without departing from the spirit and scope of the invention. All such modifications are intended to be included within the scope of this invention, which is to be limited only by the following claims.

REFERENCE NUMERALS

(45) 1 hybrid electroslag cladding system 2 flux feeder 3 cladding head 4 strip electrode 5 cladding power supply 6 workpiece 7 metal cored hybrid electroslag cladding wire 8 hot wire power supply 9 weld puddle 10 flux 11 arrow 12 cladding layer 13 controller 14 magnetic steering device 15 steering magnet 16 metal cored wire feeding mechanism 17 strip wire feeder 18 metal cored hybrid electroslag cladding wire feeder