DE1303517B - - Google Patents

Description

Mart alloys based on cobalt-chromium-tungsten have only a low resistance to pronounced oxidizing attack media. Like attempts / own, the I laiipi cause is this haliene tungsten. Table I shows an alloy of about 2 "" C and about 30 "" Cr. about 0.2 ",, Si Ivw. Mn. Rest Iiisen. in which the liisen gradually through Co, W. Co ι W + Mo. Co + W + Mo -t- Cu and

low resistance that was replaced in the alloys ent- 5 Co -t- W ι Cu + Ni.

Chemical composition and weight loss in g irrh in boiling 3 ()% nitric acid of alloys, to determine the influence of the individual alloy components on the corrosion behavior

made of alloys

0.21 0.21 29.0 20.6 ; 39.5 0.19 0.06 29.9 20.3 (.22 0.15 29.6 20.1 ί 38.4 0.15 0.22 30.0 ! 9.0 ! 39.7 0.16 0.1 p 29.6 14.7 40.9 0.17 0.17 30.3 16.2 j 37.6 0.42 0.32 28.5 i 27.9 0.46 0.32 28.0

ScliiiiL-l / c j L 'Si I Mn

1 j 2.25

2 j 2.18

3 2.15

4 2.18

5 2.18

6 2.18

7 2.30

8 2.26

Ί \ K R1-.1 hercchnei.

From the weight losses specified at the same time as the room and boiling temperature in 30% Nitric acid is the major increase in weight loss gain through tungsten (melt 3). The simultaneous addition of cobalt in the melt 4 it reduces the weight loss again, but the -little weight losses become the tungsten-free Alloys I and 2 no longer achieved. Chromium-cobalt alloys therefore have the highest resistance which otherwise contain no additional elements.

Investigations into the corrosion behavior of carbides showed that niobium-vanadium and Tantalum carbide are very resistant to oxidizing stress. This results in the Possibility of adding these elements that m the Martalloy present as carbides, increasing their wear resistance without reducing the durability to impair against oxidizing media.

Tests on alloys. which niobium. Containing vanadium or tantalum instead of tungsten showed that the weight losses in boiling 30% nitric acid are all below 1 gm ² h and on average 0.5 gm ² h. Martial circles were measured between 53 and 61 Rc.

The alloy range of the martial alloys described above. which are also resistant to oxidizing media, lies within the following limits: 0.3 to 4.0% C. 15 to 40% Cr. 0 to } .y ,, Si. 0 to 2.0% Mn. 38 to 80% Co. 2.5 to 18 ",, Nb. Ta or V. individually or in groups. The remainder is iron, in particular 0.7 to 2.5% C. 28 to 30% Cr. 0.15 to

do

Ni

Il-

ii. · in jj nr'li

2.8 ^: - 68.3 3.0 2.0 28.2 3.4 1.85 10.7 47.3 19.3 8.8 - 2.1 5.3 2.3 0.2 0.2

.ill ",, .ill ",, INO ₁ KT ΙΙλΟ, mini 0.04 ] 1 0.06 : .7 6.9 113 2.7 3.4 0.8 0.8 8.5 0.02 1.44 0.03 3.62

0.45% Si, 0.06 to 0.32% Mn, 45 to 60% Co. 2.5 to 18% Nb. Ta or V, remainder iron. With silicon contents The flow properties of the melt pool are above 1% favorably influenced in vision welding.

It was also found that hard alloys based on cobalt-chromium-niobium or Cobalt-chromium-tantalum and cobalt-chromium-vanadium base through the addition of copper, molybdenum and nickel Corrosion resistance can be as high in reducing acids as in martial alloys on a cobalt-chromium-tungsten basis, provided copper. Molybdenum and nickel added together with copper content of 0.2 to 6%. Molybdenum content c from 0.3 to 6% and nickel content from 0.5 to 10% with a corresponding reduction in the Cobalt contents are effective and of technical interest. Hard alloys containing niobium, tantalum and vanadium with appropriate additives thus have a high level of corrosion resistance in both reducing as well as oxidizing acids.

The weight losses in sulfuric and nitric acid for a test alloy are used to confirm this statement reproduced with the following composition:

1. 1.84% C. 1.24% Si. 0.2% Mn. 28.6% Cr. 5.0% Nb. 6.2% Ni. 3.55% Mo.1.5% Cu. 2.6 ",. Fe. Rest Co.

2.187% C. 1.10% Si. 0.32% Mn. 29.5% Cr. 4.72%, Ta. 7.5% Ni. 3.74% Mo. 1.48% Cu. 3.5% Fc. Rest Co.

3. I. 98% C. 1.17% Si. 0.17% Mn. 28.4% Cr. 5.24 ",, V. 7.8% Ni, 3.46% Mo. 1.65% Cu, 3.12% Fc. Balance Co.

Weight loss in g / m ² h

Veristempriitiir Room temperature

Boiling temperature

10%

0.008 0.012 0.009

0.72 0.84 0.94

20%

0.011 0.014 0.013

1.13 1.14 1.25

10%

0.003 0.007 0.007

0.09 0.11 0.13

0.003
0.008
0.008

0.2

0.27

0.24

0.003
0.005
0.008

0.6
0.8
0.65

40%

0.003 0.003 0.006

1.1

1.25

1.35

The touched weight losses / own, youIi this 1. Alloy glycols are resistant to reducing acids as well as oxidizing acids are. These types of energy are also subject to wear and tear the comparable types of alloy containing wolirani overlay. Hamlet they are at the outside welding less susceptible to cracking than the corresponding tungsten-enveloping alloys.

The subject of the invention is therefore the use of llart alloys with 0.3 to 4.0% C, 15 to 40% Cr, 0 to 3.5% Si, 0 to 2% Mn. 3 "to M)"! ·· "Co. 2.5 to 18% Nb, Ta, V individually or in groups. Residual iron and unavoidable impurities for use in oxidizing liquid attack media and the use of hard alloys with 0.3 up to 4.0% C, 15 to 40% Cr, 0 to 3.5% Si, 0 to 2.0% Mn. 38 to 80% Co. 2.5 to 18% niobium, tantalum, vanadium individually or in several, 0.2 to 6% copper, 0.3 to 6% molybdenum and 0.5 to 10% nickel, the remainder iron and unavoidable impurities for use in oxidizing and / or reducing agents liquid attack media.

Claims (2)

Patent claims: 1. Use of an I alloy with 0.3 to 4.0 "- '.. C 15 to 4 (Γ" ·' ,, Cr. 0 to 3.5% Si, 0 bit: 2% Mn. 38 to 80 "" Co, 2.5 to 18% Nb, Ta, V individually ίο or to several, remainder iron and unavoidable Impurities for use in oxidizing liquid attack media. 2. Use of a hard alloy with 0.3 to 4.0% C. 15 to 40 "" Cr. 0 to 3.5% Si, 0 to 2% Mn, 38 to 80% Co, 2.5 to 18% Nb. Ta, V individually or in groups, 0.2 to 6% Cu, 0.3 to 6% Mo and 0.5 to 10% Ni, remainder iron and unavoidable impurities for use in oxidizing, reducing liquid attack media.