On the issue of magnetism arising from cold working of austenitic stainless steels
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This post was last edited by 2311090 on 2009-10-20 at 11:13. Austenitic stainless steel is often subjected to cold forming (such as cold stamping of heads) due to its excellent toughness and ductility at room temperature. However, if the degree of deformation is large, magnetism often appears at the deformed areas. According to relevant literature, this is due to the martensitic transformation of the austenite structure resulting from cold deformation. Is there any standard that permits or prohibits the existence of such magnetism? Could everyone discuss the impact of this situation on the performance of stainless steel equipment? As container manufacturers, what would you do in such a situation? Is it necessary to carry out solution treatment? Additional note: Today I saw a post stating that heat treatment should be applied when the cold working deformation of austenitic stainless steel exceeds 15%; this requirement is likely intended to address such situations. I don’t know where this requirement comes from?
How can a phase transition occur without a change in temperature? In austenitic stainless steel, it is necessary to prevent the formation of ferrite, as this can affect the weldability of the steel/
Data shows that cold working of austenitic stainless steel results in the formation of a small amount of induced martensite; hitting the austenitic stainless steel with a hammer will make it magnetic
3# 2311090: The induction of martensite is unclear, but it can be tapped with a hammer. What material is it? Stainless steel requires special protection during processing and lifting.
4# baictq – it’s not necessary to use a hammer to strike it; even a 304 thin sheet bent twice will still exhibit magnetism. Therefore, cold-rolled austenitic stainless steel sheets must undergo solution treatment at the end
I have indeed seen this phenomenon, and I have also looked up information; it’s basically as the original poster said. However, I haven’t seen any standards requiring the avoidance of this phenomenon or the improvement of such a situation.
I’ve seen that too... Generally, austenitic stainless steel does not require heat treatment because it has good toughness. This indicates that the deformation in your case is quite significant... Ask someone who has actually worked with this type of equipment···
The magnetic strength of 304 stainless steel increases with rising Cr/Ni ratios and degree of deformation, as cold deformation induces the formation of martensite, which is magnetic. In fact, the greatest drawback of cold deformation is not magnetism but rather work hardening, along with extremely high residual stresses. I have never seen heat treatment being applied after such significant deformation. But my friend encountered a case during supervision where the client requested solubilization treatment to eliminate cold deformation stress.