GB1558940A

GB1558940A - Welding material for dissimilar fusion welding of cast iro

Info

Publication number: GB1558940A
Application number: GB2760177A
Authority: GB
Original assignee: Vereinigte Edelstahlwerke AG
Current assignee: Vereinigte Edelstahlwerke AG
Priority date: 1976-07-29
Filing date: 1977-07-21
Publication date: 1980-01-09
Also published as: DE2728777A1; ATA557576A; FR2359680B1; DE2728777C3; CH631100A5; CA1080514A; FR2359680A1; DE2728777B2; AU2671477A; AU509194B2; AT342381B; BR7704950A

Abstract

The invention relates to a weld filler metal for the heterogeneous fusion welding of cast iron, in particular spheroidal-graphite cast iron. To solve the problem of obtaining with a weld filler metal, consisting of a nickel-based alloy, welding results which produce completely satisfactory technological characteristics transversely to the welding direction even in the edge area of the welding zone without special heat treatment of the welded parts, the weld filler metal according to the invention, with regard to the weight of the alloy constituents, contains at least 75% Ni, max. 2.0% C, 0.05 to 5.0% Si, 0.1 to 20.0% Mn, 0.5 to 5.0% Ti, Nb/Ta and/or Zr, 2.0 to 20.0% Co and max. 15.0% Fe. <IMAGE>

Description

(54) WELDING MATERIAL FOR DISSIMILAR FUSION WELDING OF CAST IRON (71) We, VEREINIGTE EDELSTAHLWERKE AKTIENGESELLSCHAFT (VEW), of Elisabethstrasse 12, Vienna. Austria, an Austrian body corporate, do hereby declare the invention. for which we pray that a patent may be granted to us. and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to the dissimilar fusion welding of cast iron, particularly (but not solely) of cast iron of the spheroidal graphite type.

There have been a number of proposals for welding cast iron, in particular cast iron containing spheroidal graphite. A distinction may be drawn fundamentally between welding methods in which a similar weld metal is aimed at, i.e. a weld metal in which the carbon is preponderantly present in the form of spheroidal graphite. and methods in which a dissimilar weld metal is produced, which consists of a nickel allov and in particular a nickel-iron alloy.

Although dissimilar fusion welding has so far offered certain improvements regarding the technical characteristics of the weld metal, the unfavourable effect of heat on the marginal transition area of the base metal has had to be ameliorated by means of subsequent heat treatment of the welded parts. What is desired is a welding material whose use yields welding results in which fully satisfactory technological properties may be obtained transversely to the welding direction, even in the marginal areas of the welding zone, without special heat treatment of the welded parts.

It is known from German Patent Specification (Auslegeschrift) 2,437,247 that with modified nickel-iron electrodes it is possible to obtain relatively high elongation values, of the order of magnitude of approximately 25%, upon taking longitudinal traction test specimens from multilayer joint welds. If welds of this kind are tested transversely to the welding direction however (transverse traction test speciments), fracture commonly occurs at quite small elongation values in the region of transition between the weld metal and the base metal, these elongation values lying usuallv below 5%.

The invention provides a method of welding cast iron bv dissimilar fusion welding using a welding material containing cobalt and comprising a nickel-base alloy containing carbon, silicon. manganese. and at least one of the carbide-forming elements titanium, niobium, tantalum, and zirconium. in which method the weld metal has the following weight percentage composition, total 100etc: Ni > 75% C S 2.0% Si = 0.05 to 5.0% Mn = 0.1 to 20.0% Ti + Nb + Ta + Zr = 0.5 to 5.0% Co = 2.0 to 20.0% Fe > 15.0% Preferably the silicon content is not more than 3% and the Mn content not more than 10%.

In the case of welding material in the form of bare wires or rods intended for welding under a protective gas, the composition of the rod or bar practically coincides with that of the weld metal. The adaptations or modifications which should be performed to obtain the desired weld metal in the case of other forms of embodiment welding material', say in the case of coated rod electrodes which may contain a proportion of the alloy components within the coating, in the case of submerged arc welding with a wire or strip in combination with an appropriate flux-powder, or in the case of cored wire welding are known and familiar to those versed in the art of welding.

During use of the welding material, the cobalt component makes itself felt in the weld metal in such manner that the forming of brittle structural constituents in the heat-affected transistion zone of the base metal is impeded in wholly unexpected manner, so that no premature fracture will occur in this region. As has been shown by extensive tests, fracture of transverse traction specimens. in which elongation values are reached of the order of magnitude of 15 to 20%, occurs in the base metal outside the transistion region after correspondingly extensive deformation.

Example 1: By way of comparison, welding joints (Vee seams) were produced with 15 mm thick plates of spheroidal graphite cast iron, using the protective gas welding method, with bare wires of a diameter of 1.2 mm, the welding operation being performed without preheating and without subsequent heat treatment. The weld metal, practically identical in composition to the wire. had the chemical compositions (in wt.%) listed in Table 1. In the case of specimens I and 2. cobalt was present in the Fe/Ni alloys only as an impurity, whereas specimen 3 corresponded to the present invention.

Table 1 Specimen Alloy Composition No. C Si Mn Ti Nb Fe Co Ni 1 0.18 0.43 1.31 0.04 1.12 31.4 0.08 rest 2 0.25 1.09 0.56 0.33 0.36 49.1 0.11 rest 3 0.15 0.47 2.81 0.15 3.10 1.72 5.91 rest The cast iron had the following chemical composition (wt.%): 3.48% C, 2.41% Si. 0.17% Mn, 0.022sic P 0.003% S and 0.047% Mg, the balance being Fe. Its yield point 6 s, amounted to 343 N/mm2 and its tensile strength6 B to 465 N/mm2, the elongation 3 5 being determined as 19.r%. Tensile test specimens (cylindrical) were taken transversely to the welding seam from the welded plates and tested in respect of their properties. The values shown in Table 2 were obtained.

Table 2 Specimen yield tensile fracture No. point strength elongation rS ei B 65 N/mm2 N/mm2 1 330 411 1.7 in the transition zone 2 327 390 1.3 in the transition zone 3 339 471 17.0 in the base metal out side the transition zone Example 2: In this case, joint welds were produced as Vee seams with the 15 mm thick cast iron plates already described in Example 1, by means of coated rod electrodes (core wire diameter 4 mm), with the following coating composition: Ca C03 .............. 43 (weight percent) Ba C03 ....... ........................... 7 D II Ca F2 7 " "7 Mn (metal powder) ....... 5 'I Ferro-Zirconium (80% Zr) . 3 " "....... 3 Ferro-Niobium (65% Nb) ... . .... ... 14 Co (metal powder) .... .... ............. 14 Potassium silicate 7 " " The chemical compositions of the core wire and of the weld metal (in wt.%) are listed in table 3.

Table 3 Alloy composition C Si Mn Zr Nb Fe Co Ni Core wire 0.11 O.U2 0.21 0.01 0.03 0.12 0.17 rest Specimen 0.12 0.39 1.51 0.42 2.85 3.2 6.25 rest No. 4 The testing of round tensile test specimens as described in Example 1, yielded the following results: Table 4 Specimen yield tensile No. point strength elongation fracture # S # B 85 N/mm2 N/mm2 4 358 463 18.5 in the base metal out side the transition zone WHAT WE CLAIM IS: I. A method of welding cast iron by dissimilar fusion welding using a welding material containing cobalt and comprising a nickel-base alloy containing carbon, silicon, manganese, and at least one of the carbide-forming elements titanium, niobium, tantalum. and zirconium, in which method the weld metal has the following weight percentage composition, total 100%: Ni > N 75% C # 2.0% Si = 0.05 to 5.0% Mn = 0.1 to 20.0% Ti + Nb + Ta + Zr = 0.5 to 5.0% Co = 2.0 to 20.0% Fe # 15.0%.

2. A method as claimed in claim 1, in which Si # 3%.

3. A method as claimed in claim 1 or 2, in which Mn # 10%.

4. A method as claimed in any of claims 1 to 3, in which the cast iron is of the spheroidal graphite type.

5. A method as claimed in claim 1, substantially as described in Example 1 or 2.

6. A welding material for the dissimilar fusion welding of cast iron. the welding material containing cobalt and comprising a nickel base alloy containing carbon, silicon, manganese, and at least one of the carbide forming elements titanium, niobium, tantalum, and zirconium, the composition of the welding material being such that, when it is used for the dissimilar fusion welding of cast iron, the resulting weld metal has the following weight percentage composition, total 100:

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Table 2 Specimen yield tensile fracture No. point strength elongation rS ei B 65 N/mm2 N/mm2

1 330 411 1.7 in the transition zone

2 327 390 1.3 in the transition zone

3 339 471 17.0 in the base metal out side the transition zone Example 2: In this case, joint welds were produced as Vee seams with the 15 mm thick cast iron plates already described in Example 1, by means of coated rod electrodes (core wire diameter 4 mm), with the following coating composition: Ca C03 .............. 43 (weight percent) Ba C03 ....... ........................... 7 D II Ca F2 7 " "7 Mn (metal powder) ....... 5 'I Ferro-Zirconium (80% Zr) . 3 " "....... 3 Ferro-Niobium (65% Nb) ... . .... ... 14 Co (metal powder) .... .... ............. 14 Potassium silicate 7 " " The chemical compositions of the core wire and of the weld metal (in wt.%) are listed in table 3.

Table 3 Alloy composition C Si Mn Zr Nb Fe Co Ni Core wire 0.11 O.U2 0.21 0.01 0.03 0.12 0.17 rest Specimen 0.12 0.39 1.51 0.42 2.85 3.2 6.25 rest No. 4 The testing of round tensile test specimens as described in Example 1, yielded the following results: Table 4 Specimen yield tensile No. point strength elongation fracture # S # B 85 N/mm2 N/mm2

4 358 463 18.5 in the base metal out side the transition zone WHAT WE CLAIM IS: I. A method of welding cast iron by dissimilar fusion welding using a welding material containing cobalt and comprising a nickel-base alloy containing carbon, silicon, manganese, and at least one of the carbide-forming elements titanium, niobium, tantalum. and zirconium, in which method the weld metal has the following weight percentage composition, total 100%: Ni > N 75% C # 2.0% Si = 0.05 to 5.0% Mn = 0.1 to 20.0% Ti + Nb + Ta + Zr = 0.5 to 5.0% Co = 2.0 to 20.0% Fe # 15.0%.

2. A method as claimed in claim 1, in which Si # 3%.

3. A method as claimed in claim 1 or 2, in which Mn # 10%.

Ni > 75% C s 2.0% Si = 0.05 to 5.0% Mn = 0.1 to 20.0% Ti + Nb + Ta + Zr = 0.05 to 5.0% Co = 2.0 to 20.0% Fe # 15.0%

7. A welding material as claimed in claim 6, in which the Si content of the resulting weld metal is not more than 3%.

8. A welding material as claimed in claim 6 or 7, in which the Mn content of the resulting weld metal is not more than 10%.

9. A welding material as claimed in claim 6, substantially as described in Example 1 or 2.