Jiuzhou Head has established for more than ten years, and many customers have reported that the stainless steel head has magnetic and magnetized phenomenon. Now we will tell you some measures to prevent the magnetization of the stainless steel head:

(1) when the head factory orders steel plates from the steel mill, it can order special steel plates for the head of stainless steel to increase the content of austenitized elements or develop new steel types within the allowed range of the standard. Foreign countries have developed non-magnetic deep drawing stainless steel TUS305M for the improvement of the stability of 304.

(2) The stainless steel cold spinning head is magnetic after forming. In order to restore its non-magnetic properties, the martensite structure can be restored to austenite structure by heat treatment. The suitable heat treatment process should be higher temperature and longer time. However, heating the stainless steel for a long time at high temperature causes the metal to oxidize and coarsen the crystal grains, thereby affecting the mechanical properties of the stainless steel. Therefore, the method of heat treatment has certain limitations. When very strict non-magnetic is required, the head material can be made of stainless steel with high content of Ni, such as steel such as oCr25Ni20, oCr23Ni13, or 310, 316 steel in AISI etc,.

(3) The head is treated by solid solution, but after treatment, the head is deformed greatly and the cost is high.

After research, the head processing manufacturer has developed a new technology, cold heading pre-pressing of the head, followed by heating to a temperature of about 250℃. Due to the cold pre-pressing, the repeated pressing during the drum pressing is reduced, the phase variable is reduced, and the spinning temperature is substantially higher than the Md point, so that the large magnetic force produced by the general cold working can be avoided. After measuring, it found that equivalent basic ≯ 2.5% ferrite content.This method is far more economical than material exchange or solid melt treatment. For non-spinning heads, cold stamping can be prepressed, and then heated to 250℃ stamping form. It is advisable to replace the heads used for special purposes, such as receiving neutron radiation in nuclear equipment and special corrosive media, with materials or solid melt treatment.

When the austenitic stainless steel head is cold pressed, it undergoes phase transformation due to plastic processing, and part of the martensite structure is generated to generate magnetism. The cold pre-pressing and warming spinning can partially avoid the magnetism of the head, and the equipment with higher requirements should still take actions to replace the material or take the method of solid solution treatment.

If operated in accordance with the above method, the possibility of magnetization of the stainless steel head will be reduced.