Preparation and Micro-analysis of the 1Cr18Ni9Ti with Different Magnetic and Same Component

Abstract

In some studies, the metal materials with different magnetic permeability and same chemical composition need to be prepared to avoid the interference caused by different compositions and make the parameter of magnetic permeability become the key variable directly. In order to prepare the metal materials with different magnetic and same component, the paper has considered other two commonly schemes, such as the casting method by adding some ferromagnetic elements and the heat-treatment process to increase its phase content of martensite or ferrite. Finally, it has been found that the cold working process was preferable if the austenitic stainless steel 1Cr18Ni9Ti with paramagnetic was selected as a raw material, because it got better control in forging ratio. The method of magnetic balance has been used to measure the relative magnetic permeability of every specimen with different hardness HB 165 (A), HRC 20 (B), HRC 25 (C) and HRC 30 (D). The metallurgical microscope, XRD, TEM and SEM has been put to use to analyse their microstructure before and after forging. The results show, the cold working process improved magnetic properties of 1Cr18Ni9Ti continuously and largely within limits by controlling different forging rate, as well as the process was not complicated. The relative rate of magnetic permeability for 1Cr18Ni9Ti and W18Cr4V (high-speed steel) could be up to 1:2.435 at 0.03 T. The 20.1 % maximum reduction of the austenite phase should be a main reason to improving magnetic permeability of 1Cr18Ni9Ti. The real magneto-crystalline anisotropy should be due to martensite or ferrite phases with strong magnetic property. The 1Cr18Ni9Ti after cold working still maintained high corrosion resistance. Furthermore, this process method was also applicable to other austenitic steels with paramagnetic and strong cold work hardening characteristics.