Why are stainless steel castings magnetic and how to demagnetize them?

Dongguan precision casting manufacturers generally find that the stainless steel precision forging waste used is not magnetized, and the chemical composition is within the 304 standard, but the products used still have a small amount of microband magnetism.

In particular, it is not too difficult to ensure the quality of 304 non-magnetic castings. The key is to find out the cause of this problem. You can refer to the following 2 points:

1. The dosage of ingredients is not operated in time. In order to control costs, the Ni limit is lowered. Between 8.0-8.2 percentage, when Cr\/Ni reaches a certain standard value, when Cr\/Ni reaches a certain value, the ferrite becomes magnetic. , at this time, the aging treatment of 10501080 degrees Celsius can be used to completely fuse the ferrite with the austenitic stainless steel and prevent magnetization.

2. Cold quenching of precision castings in Dongguan City. During the cold drawing process, the austenitic stainless steel stainless steel plate produces deformed austenite. The deformed austenite promotes the improvement of the compressive strength of the steel plate, and the deformed austenite is magnetic. Choose aging treatment Even quenching can make the deformed austenite disappear, but the compressive strength of the steel will be reduced.

Assuming that the cold drawing strength must be ensured at the same time, and the weak tape or even no tape must be ensured, the following demagnetization method can be selected:

1. According to the basic principle of the phase diagram, reduce the Cr\/Ni value, especially increase the Ni.Mn component to the limit. Perform limited aging treatment before cold drawing, and control the grain size to level 4 while ensuring the surface layer; it can Reduce magnetization after cold drawing.

2. Under normal circumstances, 304 has a very weak tape after cold drawing. After impact or other impact, it still has a certain austenitic structure with a certain austenitic stainless steel mechanism. The temperature is increased to 1050 degrees, and then Water quenching cooling can remove the tape.