Effect of Crystallographic Texture on Anisotropy of Mechanical Properties in High Strength Martensitic Steel

The thermomechamcal controlled processing (TMCP) is widely applied for one of the effective processes to improve strength and toughness of steel plates. In actual application, anisotropics of mechanical properties arising from crystallographic texture which is grown up in controlled rolling process are important issues. In this study the effect of texture on anisotropies of mechanical properties by experimentally manufactured YP960 MPa class steel plate was investigated. Strength varied through plate thickness from surface to mid-thickness. At surface, strength in longitudinal direction was higher than that in transverse direction, in contrast, strength in transverse direction was higher than that in longitudinal direction at mid-thickness. The major components of texture at plate surface were {110}< 111 > and {112}< 111 >, whereas those at mid-thickness were {332}< 113 > and {211}similar to{311}< 011 >. It is considered that the texture of plate surface was formed by shear strain in austenite region, and, that of mid-thickness was grown up by compressive strain Crystal plasticity analysis based on texture information of the specimen revealed that the anisotropies of mechanical properties were strongly affected by microstructure orientation.