Stainless austenitic low Ni steel alloy
An austenitic stainless steel alloy having the following composition in percent of weight (wt %): 0.02≦C≦0.06; Si<1.0; 2.0≦Mn≦6.0; 2.0≦Ni≦4.5; 17≦Cr≦19; 2.0≦Cu≦4.0; 0.15≦N≦0.25; 0≦Mo≦1.0; 0≦W≦0.3; 0≦V≦0.3; 0≦Ti≦0.5; 0≦Al≦1.0; 0≦Nb≦0.5; 0≦Co≦1.0; the balance Fe and normally occurring impurities, wherein the contents of the alloying elements are balanced so that the following conditions are fulfilled: Ni eqv −1.42*Cr eqv ≦−13.42; and Ni eqv +0.85*Cr eqv ≧29.00 wherein Cr eqv =[% Cr]+2*[% Si]+1.5*[% Mo]+5*[% V]+5.5*[% Al]+1.75*[% Nb]+1.5*[% Ti]+0.75*[% W] Ni eqv [% Ni]+[% Co]+0.5*[% Mn]+0.3*[% Cu]+25*[% N]+30*[% C]; and −70° C.<MD30<−25° C., wherein MD30=(551−462*([% C]+[% N])−9.2*[% Si]−8.1*[% Mn]−13.7*[% Cr]−29*([% Ni]+[% Cu])−68*[% Nb]−18.5*[% Mo])° C.
1. An austenitic stainless steel alloy having the following composition in percent of weight (wt %):
0.02≦C≦0.06
Si<1.0
2.0≦Mn≦6.0
2.0≦Ni≦4.5
17≦Cr≦19
2.0≦Cu≦4.0
0.15≦N≦0.25
0≦Mo≦1.0
0≦W≦0.3
0.035≦V≦0.05
0≦Ti≦0.5
0≦Al≦1.0
0≦Nb≦0.5
0.025≦Co≦0.04
the balance Fe and normally occurring impurities,
wherein the contents of the alloying elements are balanced so that the following conditions are fulfilled:
Ni eqv −1.42*Cr eqv ≦−13.42; and
Ni eqv +0.85*Cr eqv >29.00
wherein
Cr eqv =[% Cr]+2*[% Si]+1.5*[% Mo]+5*[% V]+5.5*[% Al]+1.75*[% Nb]+1.5*[% Ti]+0.75*[% W]
Ni eqv =[% Ni]+[% Co]+0.5*[% Mn]+0.3*[% Cu]+25*[% N]+30*[% C];
and
−37° C.<MD30<−25° C.
wherein
MD30=(551−462*([% C]+[% N])−9.2*[% Si]−8.1*[% Mn]−13.7*[% Cr]−29*([% Ni]+[% Cu])−68*[% Nb]−18.5*[% Mo])° C.
2. The austenitic stainless steel alloy according to claim 1 wherein the contents of the alloy elements in the steel alloy are balanced such that the following condition is fulfilled:
Ni eqv −1.42*Cr eqv ≧−16.00.
3. The austenitic stainless steel alloy according to claim 1 wherein the contents of the alloy elements in the steel alloy are balanced such that the following condition is fulfilled:
Ni eqv +0.85*Cr eqv ≦31.00.
4. The austenitic stainless steel alloy according to claim 1 wherein the contents of the alloy elements in the steel alloy are balanced such that the following condition is fulfilled:
Ni eqv +0.85*Cr eqv ≦30.00.
5. The austenitic stainless steel alloy according to claim 1 wherein 0.2≦Si≦0.6 wt %.
6. The austenitic stainless steel alloy according to claim 1 wherein 2.0≦Mn≦5.5 wt %.
7. The austenitic stainless steel alloy according to claim 1 wherein 2.0≦Mn≦5.0 wt %.
8. The austenitic stainless steel alloy according to claim 1 wherein 2.5≦Ni≦4.0 wt %.
9. The austenitic stainless steel alloy according to claim 1 wherein 17.5≦Cr≦19 wt %.
10. The austenitic stainless steel alloy according to claim 1 wherein 0≦Mo≦0.5 wt %.
11. The austenitic stainless steel alloy according to claim 1 wherein each of W, V, Ti, Al, Nb is ≦0.2 wt %.
12. The alloy according to claim 1 , wherein the amounts of each of the elements W, V, Ti, Al, and Nb≦0.1 wt %, and where
(W+V+Ti+A1+Nb)≦0.3 wt %.
13. An article comprising the austenitic stainless steel alloy according to claim 1 .
14. The article according to claim 13 wherein the article is a wire, a spring, a strip, a tube, a pipe, or a bar.
15. The article according to claim 13 wherein the article is an article manufactured by cold-heading or forging.