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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。
A triangular specimen was designed. The surface tensile stress in the isosceles triangle section of the specimen is constant when a bending load is applied. The vibration test machine was used to carry out the fatigue test on the designed sample to study the characteristics of fatigue crack initiation and development on the surface of welded metal. The results show that the fatigue short crack originates in the slip band in the ferrite crystal. With the increase of fatigue cycles, the development of short cracks is mainly characterized by increasing crack density. The confluence of short cracks leads to the development of cracks and the crack path is dominated by transgranular.