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Reasons for magnetic properties of the 304 stainless steel castings
- Nov 24, 2017 -

General precision casting manufacturers will find that the precision casting of 304 stainless steel casting scrap will not appear magnetic. The 304 stainless steel casting test composition is in the range of 304 standard, but the products that are cast will have some micro.


In fact, it is not particularly difficult to achieve the nonmagnetic casting of 304 stainless steel castings, mainly to find the cause of the problem. First, it is because the chemical component equivalent control is not in place.


In order to reduce the cost, the general 304 stainless steel casting manufacturer will control the Ni lower limit between 8.0 - 8.2 %. When Cr / Ni reaches a certain value, a certain amount of ferrite will appear in the microstructure of steel. The ferrite is magnetic. At this time, use the 1050 ~ 1080 ℃ solution treatment and completely dissolve the ferrite into austenite, then it will not appear magnetic.


304 stainless steel castings appearing magnetic may also be due to the appearance of cold working hardening. When austenite stainless steel is cold working, the strain-induced martensite is produced, which makes the strength of stainless steel increase greatly. And the strain-induced martensite is magnetic.


If the 304 stainless steel casting uses the solution treatment or annealing, the strain-induced martensite will disappear, but the strength of the steel will also decrease. To ensure the cold working strength of 304 stainless steel castings, attention should be paid to the use of weak magnetic or even nonmagnetic methods.