GB2250030A

GB2250030A - Flux-cored wire containing elements and/or metallic hard substances; spraying; welding

Info

Publication number: GB2250030A
Application number: GB9124880A
Authority: GB
Inventors: Hans-Theo Steine
Original assignee: Castolin SA
Current assignee: ECG Immobilier SA
Priority date: 1990-11-22
Filing date: 1991-11-22
Publication date: 1992-05-27
Anticipated expiration: 2011-11-22
Also published as: GB2250030B; FR2669645A1; GB9124880D0

Abstract

The flux of flux-cored wire for use in arc-welding, or metal spraying comprises, with respect to the total weight of the wire, 0.05 to 15% by weight of elements having a negative enthalpy of formation for oxides of 200 to 800 kcal/mol and/or 2 to 40% by weight of metallic hard substances. The elements may be selected from Al, B, Nb, Ta, Ti, V, Y, Zr and alloys and mixtures thereof. The metallic hard substance is preferably a metallic boride or a carbide material which may include Si and/ or B.

Description

FLUX-CORED WIRE AND ITS USE The invention relates to a flux-cored wire and its use, e.g. for the production of layers with a high bonding strength by thermal spraying of the wire.

In general, flux-cored wires are not on a large scale in industry. The resultant bonding strength, relative to the base material, is often below 20 N/mm, depending on the process used.

In particular, thermally-loaded components coated with flux-cored wires with a high hard material content, undergo stresses that result in the layer flaking off in a zone adjacent to the base material. Corresponding difficulties are also found in the case of components which are subjected to vibration.

A novel flux-cored wire is defined in claim 1.

Further embodiments are in the subsidiary claims.

In extensive tests, it was surprisingly found that the addition of additives of elements with an enthalpy of formation for oxides of between 200 and 800 kcal mol at ambient temperature and a proportion relative to the fluxcored wire filling of from 0.05 to 15.0% by weight, in the spraying operation, provides improved bonding tensile strength, in dependence on the spraying process used, such as arc, wire or autogenous wire spraying. In particular, the values found are generally by from 5 to 10 N/mm higher than those without using such additives.

A flux-cored electrode is a filler-metal electrode, used in arc-welding, consisting of a metal tube or other hollow configuration in the form of a bare metal wire, and containing in the core materials which include flux ingredients to provide such functions as protection of the molten metal from the atmosphere, deoxidation, and arc stabilisation, and which may include alloying elements.

For example, flux-cored corrosion-resisting chromium and chromium-nickel steel electrodes are normally used for flux-cored arc-welding, and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0% and nickel does not exceed 50.0%.

In accordance with further features of the process according to the invention, the proportion of elements with a high negative enthalpy of formation for the oxides is 0.5 to 10%, wherein proportions in the core of 0.05 to 15% by weight, in particular 0.5 to 10% by weight, of elements such as Al, B, Nb, Ta, Ti, V, Y, Zr and/or alloys or mixtures thereof, relative to the overall weight, are preferred.

It has been found particularly advantageous if, as mentioned, there is added to the core a proportion of 0.05 to 15% by weight, preferably 0.5 to 10% by weight, of the elements Al, B, Nb, Ta, Ti, V, Y, Zr and/or mixtures and alloys thereof, but the proportion of B is 0.05 to 8% by weight, preferably 0.1 to 1.5% by weight.

It has also proven to be advantageous to add to the core a proportion of 0.05 to 15% by weight, preferably 0.5 to 10% by weight, of the elements Al, B, Ti, individually or in conjunction, and in particular in that respect the proportion of B is 0.05 to 8% by weight, preferably 0.1 to 5.0% by weight.

If in accordance with the invention there is added to the core a proportion of 0.05 to 15% by weight, preferably 0.5 to 10% by weight, of the elements Al, Ti, Y, individually or jointly, that may be effected individually or jointly, in which respect the proportion of Y is 0.05 to 2% by weight, preferably 0.1 to 1.5% by weight.

It is in accordance with the invention for the proportion of metallic hard substances in the core of the flux-cored wire for forming complex hard phases to be between 2 to 40% by weight, preferably 5 to 35% by weight or 8 to 20% by weight, with respect to the total weight.

In that connection, the silicon content in the proportion of the metal silicon hard material mixture can vary between 0.1 to 9% by weight, preferably 0.5 to 8.0% by weight, with respect to the total weight.

The total boron content in the proportion of the metal boride hard material mixture should be between 0.1 to 8.0% by weight, preferably 0.1 to 6.5% by weight, and/or the total carbon content in the proportion of the carbide hard material mixture should be between 0.1 to 10% by weight, preferably 0.5 to 6.0% by weight.

In accordance with a further feature the total content of silicon and boron in the proportion of the metal hard material mixture is between 0.1 and 7.0% by weight, preferably 0.1 to 5.0% by weight, whereas the total content of silicon and carbon is between 0.1 to 8% by weight, preferably 0.1 to 6.5% by weight.

In accordance with the teaching of the invention, boron and carbon are present in the component of the metallic hard material mixture, between 0.1 to 7% by weight, preferably 0.1 to 6% by weight.

In accordance with the invention the total content of boron, silicon and carbon in the proportion of the metallic hard material mixture is between 0.5 and 9% by weight, preferably 1 to 8% by weight.

The following Tables indicate elements which, when added to the flux-cored wires, result in an improvement in the bonding tensile strength.

The accompanying drawing is a graph that shows the rise in enthalpy in units of heat/mol in the relationship of various elements relative to each other.

TABLE 1 Enthalpy of formation H25 kcal/mol Al203 ~ 400.0 B203 ~ 304.2 Ce2O - 260.2 La2O3 428.6 Nb205 454.6 sio, - 217.7 Ta2O5 489.0 Ti203 - 363.49 587 587.75 Ti305 - .

Tio2 - 225.8 V203 - 293.0 V205 - 372.3 Y205 - 455.4 Zr 2 - 262.3 TABLE 2 H28 kcal/mol Cr203 - 267.0 2CaO. SiO2 - 539.0 2CaO .V205 738.2 Li2O. 2SiO2 621.0 Li2O. B203 803.6 Mn304 - 331.4 3Na2O . V205 845.1

Claims

CLAIMS 1. A flux-cored wire, the flux comprising, with respect to the total weight of the wire, 0.05 to 15% by weight of elements having a negative enthalpy of formation for oxides of 200 to 800 kcal/mol and/or 2 to 40% by weight of metallic hard substances.
2. A wire according to claim 1, which comprises 0.5 to 10% by weight of said elements.
3. A wire according to claim 1 or claim 2, wherein said elements are selected from Al, B, Nb, Ta, Ti, V, Y, Zr and alloys and mixtures thereof.
4. A wire according to claim 3, wherein said elements are selected from Ti, Al and B or Y.
5. A wire according to claim 3 or claim 4, which comprises 0.05 to 8% by weight B.
6. A wire according to claim 5, which comprises 0.1 to 1.5% by weight B.
7. A wire according to claim 3 or claim 4, which comprises 0.05 to 2% by weight Y.
8. A wire according to claim 7, which comprises 0.1 to 1.5% by weight Y.
9. A wire according to any preceding claim, which comprises 5 to 35% by weight of the metallic hard substances.
10. A wire according to claim 9, which comprises 8 to 20% by weight of the metallic hard substances.
11. A wire according to any preceding claim, which comprises metallic silicon hard material, including, with respect to the total weight, 0.1 to 9% by weight Si.
12. A wire according to claim 11, wherein the metallic silicon hard material includes, with respect to the total weight, 0.5 to 8.0% by weight Si.
13. A wire according to any of claims 1 to 10, which comprises metallic boride hard material including 0.1 to 8% by weight B.
14. A wire according to claim 13, including 0.1 to 6.5% by weight B.
15. A wire according to any of claims 1 to 10, which comprises carbide hard material including 0.1 to 10% by weight C.
16. A wire according to claim 15, including 0.5 to 6.0% by weight C.
17. A wire according to any of claims 9 to 16, wherein the metallic hard material includes between 0.1 and 7.0% by weight Si and B.
18. A wire according to claim 17, including 0.1 to 5.0% by weight Si and B.
19. A wire according to any of claims 9 to 16, wherein the metallic hard material includes 0.1 to 8% by weight Si and c.
20. A wire according to claim 19, including 0.1 to 6.5% by weight Si and C.
21. A wire according to any of claims 9 to 16, wherein the metallic hard material includes 0.1 to 7% by weight B and C.
22. A wire according to claim 21, including 0.1 to 6% by weight B and C.
23. A wire according to any of claims 9 to 16, wherein the metallic hard material includes between 0.5 and 9% by weight B, Si and C.
24. A wire according to claim 23, including 1 to 8% by weight B, Si and C.
25. A wire according to any preceding claim, wherein the flux has at least one hybrid phase consisting of two hard substances.
26. A process in which a wire according to any preceding claim is used for bonding two layers.
27. A process according to claim 26, which comprises fluxcored arc-welding.
28. Two layers bonded by means of a wire according to any of claims 1 to 25 or a process according to claim 26 or claim 27.