Der Fremde » Analysis of Magnetic Problems in Stainless Steel Pipe

Seamless sanitary grade industrial stainless steel pipe is produced by the three-roll mill cold rolling, and some customers believe that the stainless steel pipe should not be magnetic, so in the inspection of steel pipe, this will be the standard to determine the pure chemical composition of steel. In fact, this is a very one-sided, unrealistic way to identify the wrong. A wide range of stainless steel pipe, according to the organizational structure at room temperature can be divided into several categories: 1, austenitic, martensite, that is, 304,316,310,321 series. 2, martensite or ferrite type, austenite, 430,420,410 and so on. Martensite is non-magnetic or weakly magnetic, austenite is magnetic or ferrite.
The above-mentioned austenite is non-magnetic or weak magnetic, and martensitic or ferrite is magnetic. Due to the composition of segregation during smelting or other reasons, will cause austenitic 304 stainless steel in a small amount of martensite or ferrite structure, so 304 stainless steel will be with a weak magnetic. In addition, 304 stainless steel after cold processing, the structure will be transformed into the Ma, cold forming the greater the degree of deformation, the greater the transformation of martensite, steel, the greater the magnetic. As a number of steel strip, the production of φ76 tube, no obvious magnetic induction, the production φ9.5 tube, due to cold deformation large magnetic induction is obvious, the production of rectangular tube deformation due to large. Especially the corner part of the deformation is more intense magnetic more obvious. In particular, it is suggested that the above-mentioned causes of the 304 stainless steel magnetic, with other materials of stainless steel, as compared with 430, both the carbon steel is not the same level of magnetic. That is, the magnetism of 304 steel always shows the weak magnetic.