Microstructure And Texture Evolution Of Cold-rolled High-manganese Austenitic Steels

With the development of science and technology of materials, excellent mechanicalproperties of high-manganese austenitic steel attract more and more attention. In theprocess of plastic deformation, the TWIP steel, produced a large number of deformationtwins which greatly increased the elongation and strength of the material. TWIP steel hasalso become a new direction of the study of ductility and high strength steel.This paper studies grain characteristics, and the evolution of microstructure, grainorientation, the formation of deformation twins and texture features during cold rolling of22Mn-13Cr-3Ni-1Mo-1Cu-0.22N steels in different solid solution temperatures throughadvanced analytical instruments including optical microscope(OM), X-ray diffraction(XRD) and EBSD.The results showed that with the increase of solid solution temperature, the grain sizeof nitrogen strengthened high manganese austenitic stainless steel increases, and itproduces a lot of annealing twins. During cold rolling, a small amount of deformation(10%) will produce deformation twins, what’s more, with the increase of cold rollingdeformation, the dislocation density increases within the sheet and the amount ofdeformation twins is also increasing. Samples with larger grain size are more prone toproduce deformation twins. However, the grain size is too large to coordinate the rotationwith other grains. For some hard oriented grains, it is difficult to turn to soft orientation tooccur plastic deformation, as a result, deformation twins are not easy to be produced.Therefore, under the deformation of45%and solution treatment in1200℃, large amountof grains will not produce deformation twins; When a small amount of deformationhappens, deformation twins are easily produced in annealing twins and some specificorientation grains, but the effect of grain orientation on deformation twins decreases withthe increase of the deformation. high manganese austenitic stainless steel sheet generates ahigher proportion of Σ3nspecial boundaries during cold rolling. After solid solutiontreatment, samples are mainly Rt-C{001}<110> and G{011}<100>. The deformationincreases, Goss texture is gradually increased accordingly. When the amount ofdeformation reaches43%, the Goss texture decreases. However, B{011}<211> textureincreases with the increase of the deformation. While the amount of deformation reaches 75%, only B{011}<211> texture is left with a volume fraction of15.98%; The textureevolution after1000℃solution treatment are more susceptible to be influenced bydeformation twins during cold rolling. Under the effect of deformation twins, orientationgrain Rt-C{001}<110> shifts to Rt-Cu{112}<110> by twins in the process of rolling.