WELDING FILLER MATERIAL

Abstract

A welding filler material includes (in wt.-%): C 0.01-0.05%; N 0.05-0.10%; Cr 20.0-23.0 %; Mn 0.25-0.50 %; Si 0.04-0.10 %; Mo 8.0-10.5 %; Ti 0.75-1.0 %; Nb 3.0-5.0%; Fe max. 1.5%; Al 0.03-0.50%; W 4.0-5.0%; Ta max. 0.5%; Co max. 1.0%; Zr 0.10-0.70% Ni remainder; and impurities resulting from the smelting process.

Claims

1. A method of using a welding filler material to weld a base material, the method comprising: providing the welding filler material, wherein the welding filler material comprises and alloy having (in wt.-%) TABLE-US-00006 C 0.01-0.05% N 0.05-0.10% Cr 20.0-23.0% Mn 0.25-0.50% Si 0.04-0.10% Mo  8.0-10.5% Ti  0.75-1.0% Nb  3.0-5.0% Fe max. 0.9% Al 0.03-0.50% W  4.0-5.0% Ta max. 0.5% Co max. 1.0% Zr 0.10-0.70% the welding filler material containing the following impurities TABLE-US-00007 P max. 0.05% S max. 0.01% V max. 0.05% Ni remainder, and impurities, wherein the welding filler material has a yield strength Rp 0.2>610 MPa in a thermally untreated weld metal, and wherein the alloy satisfies the following conditions:
Zr/C>7
Nb/C>100; and adding the welding filler material to the base material in a welding process to form a weld seam in the base material.

2. The method according to claim 1, wherein the welding material has (in wt.-%) TABLE-US-00008 Zr 0.3-0.65%.

3. The method according to claim 1, wherein the alloy satisfies the following condition:
Ti/N>10.

4. The method according to claim 1, wherein the welding filler material has a yield strength Rp 0.2>640 MPa, in the thermally untreated weld metal.

5. The method according to claim 1, wherein the alloy satisfies the following condition:
Zr/C>10.

6. The method according to claim 1, wherein the alloy satisfies the following condition:
Nb/C>150.

Description

[0011] Advantageous further developments of the material according to the invention can be found in the dependent claims.

[0012] The invention relates to a welding filler material composed of a nickel-based alloy, which is suitable for producing weld metals having a very high mechanical yield strength. The welding filler material achieves this very high yield strength in the weld metal without subsequent further heat treatment.

[0013] The element iron is indicated at max. 1.5%, wherein contents 1.2%, in particular 0.9% are also possible.

[0014] According to a further idea of the invention, the material has a yield strength, Rp 0.2 above 610 MPa in the thermally untreated weld metal. The material according to the invention differs from the state of the art by means of the modified titanium and zirconium contents, wherein the element nitrogen is intentionally alloyed in here.

[0015] In the studies of the material according to the invention, it was found that a titanium content of 0.75-1.0% on the one hand makes a contribution to an increase in the yield strength, but does not bring with it any excessive embrittlement of the weld metal. Furthermore, it was found that the dependence of the mechanical/technological values in the weld metal is independent of the heat management during welding, to a great extent.

[0016] The element zirconium is indicated in a range between 0.10% and 0.70%. Contents in the range between 0.30% and 0.65% are preferred ranges here. In this connection, studies have shown that Zr preferentially forms carbides with the alloy element C, which carbides are present in finely dispersed form and thereby bring about an extraordinary increase in strength (FIG. 2). This recognition is new in that until now, Zr has been used as an alloy element only in the case of high-temperature alloys and heat conductor alloys. In this connection, it is known that in the case of high-temperature alloys and heat conductor alloys, Zr can improve the long-term high-temperature resistance and adhesion of scale layers. However, until now it has not become known that Zr is able to significantly improve the mechanical properties in the case of room temperatures and temperatures below that of a welding filler material.

[0017] Nitrogen is indicated between 0.05% and 0.10%. N is an element that very greatly increases the pitting corrosion resistance and crevice corrosion resistance of the material when dissolved interstitially. However, N also forms finely dispersed TiN with Ti (FIG. 2). Studies have shown that the yield strength increases greatly as the result of the combination of nitrogen and titanium, due to the formation of titanium nitride. Furthermore, the addition of nitrogen prevents Ti from forming the gamma' phase with Ni, which leads to the disadvantages mentioned above.

[0018] It was surprisingly found in the studies that in addition to the elements Cr, Mo, Nb, which harden mixed crystals, an effect with which the target minimum yield strength can be reached in the thermally untreated weld metal, with simultaneously good ductility, only by the sum of the carbide-forming and nitride-forming alloy elements Zr, N, C, Ti, Nb.

[0019] Impurities are contained in the alloy according to the invention as follows:

TABLE-US-00002 P max. 0.05% S max. 0.01% V max. 0.05%

[0020] The combination of high yield strength and good ductility is achieved if the following ratios (information in mass-%) of the elements Zr, N, c, Ti, Nb are adhered to: [0021] [Zr]/[C]>7, more advantageously>10 [0022] [Ti]/[N]>10 [0023] [Nb]/[C]>100, in particular >150

[0024] The addition of manganese improves heat crack resistance by means of the formation of MnS. Furthermore, it was also found that manganese also makes a contribution to increasing the yield strength in the weld metal.

[0025] In the studies of the material according to the invention, it was found that at least 0.04% silicon are required for good weldability, but that silicon is not allowed to be greater than 0.10%, so as not to worsen the heat crack resistance.

[0026] It was possible to hot-roll laboratory ingots produced from the composition according to the invention, with batch sizes of 100 kg (Table 2), without problems, wherein it was possible to determine that the hot-rolling temperature should preferably lie between 950° C. and 1180° C. Subsequently, it was possible to further process and finish the hot-rolled laboratory ingots mechanically, to produce the desired dimensions.

[0027] Thin square rods having an edge length of approximately 4 mm were cut from the rolled laboratory sheets having the compositions in Table 1 and 2. Using these square rods, a weld metal sample was produced according to ISO 15792-1, by means of the TIG method, and subsequently the mechanical/technological tests were conducted. The results of the studies are listed in Table 1 and 3.

TABLE-US-00003 TABLE 1 Alloys studied (laboratory batches - 10 kg) KV2 Lab. Rp0.2 KV2 (−196° No. W Co C Mn Ti N Zr [MPa] (RT, J) C., J) 250441 3 15 586 105 74 250442 3 10 552 112 55 250443 4 10 537 105 89 250445 3 10 0.03 561 98 73 250446 3 5 0.03 524 94 80 250447 10 1.5 644 24 14 250478 0.5 0.5 586 100 84 250479 1 0.5 612 77 75 250484 1 0.2 601 67 59 250486 3 1 0.1 578 81 54 250487 3 0.03 0.1 0.5 644 97 87 250488 3 5 0.03 0.1 0.2 623 105 89

TABLE-US-00004 TABLE 2 Smelt analysis of the pilot plant batch PV864 (100 kg) Chem. Element PV 864 C 0.020 Si 0.070 Mn 0.350 P 0.010 S 0.0020 Al 0.0700 Cu 0.0100 Cr 22.00 Ni 58.00 Mo 9.300 V 0.020 Ti 0.900 Nb 3.300 Co 0.0300 Fe 1.00 W 4.40 N 0.0670 Zr 0.60

TABLE-US-00005 TABLE 3 Mechanical/technical values of the pure weld metal from the pilot plant batch PV864 Rp0.2 RP1.0 RM A5 KV2 PV 864 (Mpa) (Mpa) (Mpa) (%) (RT, J) weld 654 701 877 34 121 metal sample 1 weld 646 690 848 31 112 metal sample 2