Strain and texture distribution of high-Mn steel plate with heterogenous microstructure after cold bending

徐 平光   ; Jiang, L.*; Wang, H. H.*; Su, Y. H.  ; 浜 孝之*; 菖蒲 敬久  

Xu, P. G.; Jiang, L.*; Wang, H. H.*; Su, Y. H.; Hama, Takayuki*; Shobu, Takahisa

To reduce the greenhouse gas emissions, liquefied natural gas (LNG) has been widely used as fuel for power stations. High-Mn steels, which are economical cryogenic steels for LNG transportand storage with excellent cryogenic strength, ductility and toughness performance, have attracted such attention as they could replace the expensive high-Ni martensite steels and high Ni-Craustenite steels. However, obvious chemical segregation usually occurs during the mass production of such steel plates, and the reasonable strain and texture distribution of the related semi-finished parts must be evaluated for wider industrial application. An irregular diffraction angle distribution of the cold-bent high-Mn steel plate was confirmed by using neutron diffraction. It was found to be related to the heterogeneous microstructure induced by the chemical segregation, as revealed by EPMA measurements. The irregular residual strain and Bragg-edge width distributions of the high-Mn steel plate, both with and without cold bending deformation, revealed the presence of macroscopic segregation bands at different thicknesses. After correcting for the heterogeneous microstructure using a fully stress-relaxed reference sample, the triaxial strain distribution through the thickness of the cold-bent high-Mn steel plate was found to be similar to that of other cold-bent steel plates.