How is austenitic stainless steel made?

[Ask1122]

Hi all, just wanted to find out how is austenitic stainless steel made? Because when you heat the steel above certain temperature, your cementite starts to diffuse out and austenite starts to form, but the thing is this: if you allow the austenite to cool down, it reverts back to cementite and ferrite, and if you quench it you will get martensite, but then how do you cool down the austenitic stainless steel to keep the austenite?

Thanks!

 

[timmay]

A variety of alloying components inhibit the transformation from austenite to other phases. A typical 300 series stainless will have high chromium content and usually ~10% nickel, which prevents the transformation. Other additives are often used to reduce nickel content, keeping costs down.

 

[Ask1122]

Thx Timmay, that make much more sense to me now. But then does it mean that all austenitic stainless steel comes in a solution annealed condition, I saw somewhere that austenitic stainless steel are not normalised, but i am not sure why?

And if the nickel and chromium prevent the transformation of austenitic stainless steel into pearlites, then how are ferritic stainless steel (e.g. gr 430) made? I see that there are only chromium in the martensitic and ferritic stainless steel, does it mean that Nickel is the only elements that prevents the transformation?

And my last question is if you by any chance know where the creep temperature range for the materials are in ASME?

Thank you for all your help!

 

[Astronuc]

These articles might be of interest:

Alloy steels
Index - http://steel.keytometals.com/default.aspx?ID=Articles#p5
Alloy steels - http://steel.keytometals.com/default.aspx?ID=CheckArticle&NM=4

Characteristic of alloying elements
http://steel.keytometals.com/default.aspx?ID=CheckArticle&NM=10

Effects on the martensite, pearlite and bainite formation
http://steel.keytometals.com/default.aspx?ID=CheckArticle&NM=51


Steels and their properties are often given in the annealed condition, but they can be forged or hot/cold worked, which does effect strength.

 

[alphy]

Austenitic stainless steel is made by adding specific elements such as nickel and chromium to steel during the production process. This creates a steel that is highly resistant to corrosion and has a higher strength and toughness compared to regular steel. The key to keeping the austenite form is to control the cooling process. This can be achieved by using techniques such as annealing or solution annealing, which involves heating the steel to a high temperature and then slowly cooling it in a controlled environment. This allows the austenite to remain stable and prevents it from transforming into ferrite and cementite. Another method is to use rapid cooling techniques, such as quenching, which can also help to retain the austenite form. The specific cooling method used will depend on the desired properties of the final product. Overall, the production of austenitic stainless steel involves carefully controlling the composition and cooling process to achieve the desired properties.