CS204976B2 - Meltable alloy with resistance to oxidation - Google Patents

Abstract

1440835 Co-Ni-Cr alloys CABOT CORP 23 Oct 1973 [24 Oct 1972] 49267/73 Heading C7A A weldable, oxidation-resistant alloy consists, by weight, of:- 0.01 to 0.33% carbon 18 to 30% chromium 8 to 30% nickel 8 to 18% tungsten 0.001 to 0.018% lanthanum 0.02 to 0.7% aluminium up to 2% manganese up to 1% silicon up to 0.02% boron up to 10% iron the balance being cobalt, not above 61%, and impurities in which phosphorus should not exceed 0.02% and sulphur not exceeding 0.015%. The composition should be arc melted in air or vacuum melted by induction, followed by electro-slag remelting.

Description

The invention relates to fusible alloys resistant to oxidation, and in particular to cobalt alloys with improved oxidation resistance, especially cobalt-based alloys containing. small but effective addition of lanthanum.

U.S. Pat. No. 3,418,111 describes a cobalt-based lanthanum-containing compound to improve the antioxidant properties of alloys of this class.

The disadvantages of these alloys are overcome by the fusible oxidation-resistant alloy according to the invention, which consists of the following components, whose content is given in a weight concentration of 0.001 to 0.33% carbon, 0.005 to 2% manganese, 0.005 to 2%. 1% silicon, trace to 0.02% phosphorus, trace to 0.015% sulfur, 18 to 30% chromium, 8 to 30%. nickel, 8 to 18% of tungsten, 0.001 to 0.018% of lanthanum, 0.02 to 0.7% of aluminum, 0.001 to 0.02% of boron, 0.005 to 10% of iron and the remainder consists of a maximum of 61% cobalt and common impurities in normal quantities.

Furthermore, it has been found that, while maintaining the narrow lanthanum content range and using at least 0.02% aluminum, it is possible to obtain an alloy with considerably better overall properties compared to known products. It has also been found that while the alloys of the present invention can be melted by methods known per se, much better control of composition and limit resistance to oxidation by melting the primary melt under vacuum induction or arc melting in air, followed by an electroslag remelting step can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. plot of average crack length versus lathan content in a die of 63.5 mm diameter;

Fig. 2 is a graph of average crack length versus lanthanum content in a die of 101.6 mm diameter;

Fig. 3 is a graph of decrease in <m versus aluminum content at 1149 ° C; the static oxidation test at various lanthanum contents and Figure 4 is a graph of weight loss versus final aluminum content at 1093 ° C; dynamic oxidation test.

In order to illustrate the favorable results obtained according to the invention, different melting temperatures were used at different lanthanum and aluminum contents. In-vitro or4949 duct melting in air or vacuum was used in the tests, followed by electroslag remelting to obtain the final alloy.

Table I

Mass concentration of alloy components in%

The various samples obtained in this manner show the composition shown in Table I below.

alloy C Mn Si WITH Cr Ni W AND 0.08 0.66 0.34 0.010 21.60 22.30 14.05 В 0.08 0.66 0.33 0.009 21.50 22.30 14.05 C 0.08 0.62 0.36 0.003 21.20 22.80 13.85 D 0.10 0.64 0.36 0.003 21.20 22.70 13.85 E 0.09 0.54 0.47 0.006 22.40 22.30 14.25 F 0.09 0.64 0.46 0.006 22.50 22.30 14.20 G 0.09 0.70 0.47 0.006 22.50 22.10 14.15 H 0.09 0.68 0.48 0.007 22.50 22.20 14.15 AND 0.12 0.80 0.26 ns 22.30 21.20 13.80 i — 1 0.08 0.66 0.32 0.006 21.90 22.40 14.05 J 0.12 0.90 0.28 ns 22.10 21.20 13.80 J-1 0.08 0.70 0.35 0.006 21.90 22.30 14.05 к 0.08 0.66 0.34 ns 21.60 22.30 14.05 L 0.08 0.66 0.31 0.010 22,00 22.30 14.15 M 0.09 0.65 0.24 0.001 21.50 21.80 14.00 N 0.10 0.59 0.22 0.001 21.94 22.15 14.11 0 0.09 0.62 0.29 0.006 20.60 22.70 13.45 P 0.10 0.66 0.44 0.001 21.82 21.87 13.85 Q 0.07 0.58 0.35 0.005 21.90 21.90 14.35

ns = not determined

Table I - continued alloy La AI В Fe Co + AND <0.005 0.23 < 0.001 2.21 В <0.005 0.04 < 0.001 2.21 + C 0.012 0.16 0,002 1.96 + D 0,008 0,43 0.003 1.96 E 0.010 0.08 0.004 1.50 + F 0.010 0.19 0.003 1.50 + G 0.011 0.31 0,002 1.46 H 0.010 0.43 0.003 1.48 + AND <0.005 <0.02 ns 2.10 4- 1—1 <0.010 <0.10 ns 2.33 J <0.005 <0.02 ns 3.22 J-1 <0.005 <0.02 <0.005 0.01 ns 2.36 + к 0.001 2.21 + L 0.005 <0.01 < 0.001 2.24 + M 0.02 0.08 0.001 1.90 + N 0.03 0.05 < 0.001 1.38 + O 0.04 0.28 0.004 2.06 + P 0.05 0.19 0.001 1.40 + Q 0.08 0.11 0,002 2.06 + + = balance of cobalt and possible impurities From these Alloys were the first twelve Results tests are listed in the following tested by oxidation resistance tests. table:

20497В dynamic static (µm) (lateral drop (m) 1149 ° C

1093 ° C

Table II

Oxidation results for samples A - L dynamic (Pa)

1093 ° C

AND -10.75 7.56 12.37 В —30.75 ns 20.36 C -20.60 8.71 8.13 D —10.45 7.39 8.84 E —30.13 10.41 10.24 F -22.47 9.37 8.80 G —10.65 8.51 9.29 H -10.58 8.05 10.24 AND -126,00 143.20 22.02 i — 1 —120.70 ns 26.77 J —780.00 101.10 48.61 1-1 —80.00 ns 10,02 К —170.85 29.80 38.54 L —210.10 30.70 36.52

ns = not determined

The oxidation tests according to Table II were identical for all alloys tested. In all cases samples of 1.524 mm thickness, 85.72 mm length and 9.52 mm width were used. One group of samples was subjected to dynamic tests, exposing the samples to a temperature of 1093 ° C.

Another group of samples was subjected to the static oxidation test at 1149 ° C for 25 hours. Subsequently, the material loss was measured and the results are given above.

Samples A to H and M to Q were subjected to fusibility tests. The test procedure is described in Metal Progress, Metal Progress News Supplement, Vol. 100,4.2, p. 7, August 1971. The test results are shown in Table III.

Table III average crack length of die radius '63, 5 mm

W die radius 101.6 mm

The noticeable improvements in the alloys of the invention in both the oxidation and fusibility tests are apparent from the comparison of alloys A to H (according to the invention) with alloys I to Q (other alloys). The improvements are best seen in the figures, in which Figures 1 and 2 show that at a lanthanum mass concentration below about 0.018%, on average very short cracks occur, while above 0.018% lanthanum, the crack length is noticeably increased. Giant. Figures 3 and 4 show that, while keeping the aluminum and lanthanum contents within the range of the present invention, the oxidation resistance of the alloy is noticeably increased, so that the combination of the critical lanthanum content and the aluminum content produces new alloys variants for producing oxidized products .

It is to be understood that the spirit of the invention is not limited to the preferred embodiment described above and that other modifications may be included without departing from the scope of the present invention.

A V C E F G H

55.88

65.27

102.36 ns

213.36 ns

L M

N.

O P

Q

45.72

398.78

322.58

551.18

388.62

975.36

0

37.08 0 0 0 0

71.12

248.92

121.92

55.88

205.74 ns = not determined

Claims (1)

OBJECT OF INVENTION Oxidation resistant fusible alloy characterized in that of the following components, the content of which is present in a concentration by weight of 0.001 to 0.33% carbon, 0.005 to 2% manganese, 0.005 to 1% silicon, trace to 0.02% phosphorus, trace up to 0.015% sulfur, 18-30% chromium, 8-30% nickel, 8-18% tungsten, 0.001-0.018% lanthanum, 0.02-0.7% aluminum, 0.001-0.02% boron, 0.005-10% % of the iron and the remainder consists of a maximum of 01% cobalt and the usual impurities in conventional amounts.