摘要
分析了同步热机械疲劳应力可应变滞后环的特征行为，在滞后环的低温段上呈现出强烈的循环硬化行为，被第二相粒子钉锚的局部位错段或整根位错脱锚引起具有两阶段应力降的大齿屈服特征，位错从未消散的气团脱锚引起弱的锯齿屈服特征。在高温阶段，溶质原子团消散，从而不能对位错运动起到障碍作用，螺位错交滑移克服第二相粒子的过程及亚晶形成表明了回复机理占主导地位，基本上不锯齿屈服特征，但仍表现出弱的循环硬化行为。温度与应变范围是决定锯齿屈服特征是否出现的决定因素，高温范围应力降现象是热机械疲劳变形特有的力学行为。
In-Phase thermo-mechanical fatigue(TMF) stress-strain hysteresis loops have been analysed.At lower temparature section of loops,stronger cycling hardening behaviour with a large amount of evident serrations was observed.Partial and whole segments of dislocation unpinning from particles of carbide resulted in larger serrations.At high temperature,dissolved solute atom clouds could not contribute to hindering dislocations from going further.Meanwhile,screw dislocation cross slip overcoming the particles of carbide and occurrence of subgrain were main mechanisms so that no serration occurred at high temperature'The phenomenon of cycling hardening with stress drop at high temperature section is characteristic mechanical behaviour for TMF.Whether serration occurred is dependent on temperature and cycling strain range.
出处
《机械工程材料》
CAS
CSCD
1996年第2期13-14,共2页
Materials For Mechanical Engineering
