ZG20SiMn铸钢的应变疲劳行为研究

Research on strain fatigue behavior of ZG20SiMn cast steel

为了深入理解ZG20SiMn铸钢在应变疲劳期间的循环变形及断裂行为,在应变控制模式下针对ZG20SiMn铸钢的疲劳行为进行了研究.结果表明,在应变控制的加载模式下,ZG20SiMn铸钢可表现为循环硬化和循环稳定特征,主要取决于外加总应变幅的高低,且其弹性应变幅、塑性应变幅与疲劳断裂时的载荷反向周次之间表现为单斜率线性行为.透射电镜分析结果表明,ZG20SiMn的疲劳变形机制主要为波状滑移机制.扫描电镜分析结果表明,在不同的外加总应变幅下,疲劳裂纹均以穿晶方式萌生于ZG20SiMn铸钢试样表面,并以穿晶方式扩展.

In order to understand the cyclic deformation and fracture behaviors of ZG20SiMn cast steel,the fatigue behavior of ZG20SiMn cast steel was investigared under the strain-controlled mode. The experimental results showthat under the strain-controlled loading mode,the ZG20SiMn cast steel can exhibit the cyclic strain hardening and cyclic stability,which mainly depends on the imposed total strain amplitude. For the ZG20SiMn cast steel,the relation between the reversals to failure and the elastic strain amplitude or plastic strain amplitude shows a single slope of linear behavior,respectively. The analysis results with transmission electron microscope( TEM) reveal that the fatigue deformation mechanism of ZG20SiMn cast steel is the wavy slip mechanism. The analysis results on the fatigue fracture surfaces of ZG20SiMn cast steel with scanning electron microscope( SEM) reveal that at different total strain amplitudes,the fatigue cracks initiate at the free surface of fatgiue specimen in a transgranular mode,and then propagate in a transgranular mode.