2Cr13钢高周疲劳微塑性损伤特性研究

Characterization of Microplasticity Damage Developed during High Cycle Fatigue in 2Cr13 Steel

研究了２Ｃｒ１３马氏体不锈钢高周疲劳载荷作用下微观塑性变形的演变过程。在三种选定循环载荷作用下，在疲劳裂纹萌生前试样一直处于弹性变形阶段，而且弹性模量基本不变。在１／２寿命时，普遍观察到局部微观塑性变形特征。有些板条内存在含扭折对的平行螺位错束或十字交叉网状位错组态，一些细长碳化物周围塞积了棱柱或滑移型位错环。达到疲劳寿命时，有些区域内形成位错胞状结构。经过高周疲劳实验的薄膜试样在透射电镜下进行动态拉伸原位观察结果表明，微裂纹易在细长碳化物处萌生，沿位错胞壁或板条界扩展后与主裂纹汇合。高周疲劳过程中局部微观塑性耗散造成一定程度的微观结构损伤。

Fatigue tests and transmission electron microscope(TEM) observation were performed to examine the characterization of microplasticity developed during high cycle fatigue in 2Cr13 steel.The specimens were being elasticity deformation under three special cycle loads before fatigue crack initiation and elastic modulus were not being changed.The characterization of local microplastic deformation was observed in specimens at half fatigue life cycles.There were many kinks in parallel screw dislocations and some screw dislocation meshes existed in a crisscross configuration.Prismatic loops and gliding loops were formed and piled up around M\-3C or M\-2C carbides in some areas.Dislocation cells were formed at some areas at fatigue life cycles.TEM observation of tensile test of the specimens after half life fraction revealed the mechanisms of the crack initiation and propagation.Microcracks initiated at carbides and propagated along the cell walls or the lath boundaries.The local microplasticity dissipation during high cycle fatigue had brought about local damage in 2Cr13 steel.It needed a little plastic work for the cracks growth through these damage regions.Characterization of Microplasticity Da mage Developed during High Cycle Fatigue in