一种等应力试样中的疲劳短裂纹行为

SHORT FATIGUE CRACK BEHAVIOUR IN ISO-STRESS SPECIMENS

设计了一种三角形试样,当施加弯曲载荷时,该试样等腰三角形段内的表面拉应力为常数。采用振动试验机对所设计的试样进行疲劳试验,以研究一种焊接金属表面疲劳短裂纹萌生和发展特征。结果表明,疲劳短裂纹起源于铁素体晶内的滑移带。随疲劳周次增加,短裂纹发展以裂纹密度不断增加为主要特征。短裂纹的汇合造成裂纹发展且裂纹路径以穿晶为主。

The fatigue tests were made on the specially designed specimens by avibration testing machine to investigate the initiation and propagation features ofshort fatigue cracks in a weld metal. The specimens were prepared of a kindof triangular shape in which the surface tensile stress is a constant. The resultsshow that the short fatigue cracks originate from the slip bands and initiate insidethe ferrite grains. The development of short fatigue cracks is marked by the grad-ual increase in crack density with fatigue cycles. The coalescence between shortcracks leads to crack propagation and the crack path is predominantly transgranular.