Research On Evolution Of Texture In Cold Rolling-Annealing Process And Weld Structure Of TCS Stainless Steel

With the development of national economy, there is a rapid increase in the development of rail freight. The trend of railway vehicles speed-raising and loading more heavier goods has put forward a higher demand on the train body materials. Not only must the body materials have good capability of corrosion resistance, but also it has to have good manufacturing process and service performance, that is, sufficient strength, good performance of the pressing and welding performance. TCS stainless steel is popularized by many railway truck factories. The Ministry of Railways also encourages the development of special stainless steel goods. However, the research and development of this kind of steel in the domestic is just the beginning. Its component-designing and processing technique are not yet perfect.For the large anisotropy and poor welding performance of TCS stainless steel, the texture evolution during cold rolling-annealing and weld structure of different alloying TCS stainless steel was investigated, and as well as the thermal simulation experiments of experimental steel with different components. The results are as following:(1) After750℃annealing, large ferrite grains form in the cold rolling strip steel of TCS345. After850℃annealing, a small amount of martensite generates in the ferrite grain boundaries. Due to strongly inhibiting recrystallization and delaying phase transformation of Ti, during750℃and850℃annealing process, recrystallization grains of B4003are small and no martensite generates.(2) In the process of cold rolling, texture evolution of TCS345and B4003is basically the same. As the reduction rate increases, strong a texture and weak y texture gradually form in the two kinds of strip steel. The texture gradient disappears along the thickness direction.(3) During annealing process of TCS345, a texture weakens, but y texture enhances and shows a certain degree of texture gradient along the thickness direction. With the annealing time extending, the intensity of y texture first enhances, then weakens. After the annealing process, a texture in B4003is still strong, but y texture is weak, and there is no texture gradient along the thickness direction. With the change of the annealing temperature and annealing time, a and y texture’s evolution is not significant.(4) Solid solution of Ti and Ti(C、N)’s precipitation would cause a significant impact to the rotation in cold rolling and growth in annealing process of grain. A large amount of Ti will inhibite{111} grains’ growing up in the annealing process.(5)1#sample contains more elements forming ferritic and its CGHAZ is ferritic grains. As the welding heat input increases, grain size increases;2#sample contains more elements forming austenite, the content of martensite increases as the welding heat input increases. Therfore, with reasonable components design and an appropriate amount of welding heat input, CGHAZ of TCS stainless steel could get the appropriate grain size and structure.