X100级管线钢的动态塑性变形行为研究

采用原位拉伸扫描电镜试验对X100级管线钢的动态塑性形变行为进行观察,并运用EBSD微观取向分析技术对形变前后管体组织的取向变化进行分析。结果表明,X100级管线钢的微观组织由针状铁素体、粒状贝氏体和M/A岛组成。在拉伸应力的作用下针状铁素体首先发生形变,随着应变的增加,针状铁素体形变累积到一定程度后,导致粒状贝氏体发生形变。针状铁素体边界和贝氏体基体上的M/A组织钉扎位错使变形不易发生。由EBSD取向可知,晶体在发生形变后轧面的{110}晶面方向沿拉伸形变方向转动。由扫描电镜照片观察到,在外加应力作用下,夹杂物成为微裂纹形核核心并随着外加应力的增加而扩展,最后连接,导致裂纹贯穿基体直至失效。

Research on Dynamic Plastic Strain of Grade X100 Pipelines

The dynamic plastic deformation behavior of X100 grade pipeline steel was observed through in-situ tensile SEM tests,and microstructure orientation deformation of the steel before and after tensile strain were analyzed by EBSD analysis technology.The result showed that microstructure of the grade X100 pipeline steel was composed of acicular ferrite,granular bainite and M/A constitute.Under the effect of tensile strain,acicular ferrite deform firstly.Acicular ferrite deformation was accumulated with strain increase,and promoted granular bainite deformation.M/A constitute pinning dislocation at the acicular ferrite boundary and in the bainite substrate caused the distortion not to be suitable occurs.According to the EBSD pole picture,crystals turn to tensile deformation orientation along {110} direction of rolling face.Obtained by the scanning electron microscope picture observation,the inclusion becomes the crack shape nuclear core.Cracks increase along with the applied stress expands under tensile stress increase,and connect together to lead finally to invalidation.