摘要
研究了孔挤压强化工艺对7A12铝合金锻件的疲劳增益效果,并通过透射电镜、扫描电镜及X射线衍射仪等设备,研究了疲劳断口的形貌特征、微观组织变化以及孔壁表层的残余应力场分布。研究结果表明,挤压过盈量为5%时,孔挤压疲劳寿命增益效果最好,是未强化的13.5倍;孔挤压后,孔壁强化层内形成了深度>9mm的残余压应力层,强化层内形成的位错胞状结构可以有效延缓疲劳裂纹的扩展速率,从而提高材料的疲劳寿命。
Experimental research has been carried out to study the fatigue life enhancing effects of cold-expansion on 7A12 aluminum alloy forging.The fatigue striation spacing was measured by scanning electron microscopy（SEM）,the dis-location introduced into the specimens due to cold hole-expansion was evaluated by transmission electron microscopy（TEM）, and the residual stresses was measured by X-ray diffraction apparatus.The results showed that when the shrink range is 5%,the fatigue life enhancing effects is the best,and the maximum fatigue life was increased to 13.5 times of the non-cold-worked specimens.The strengthening layer depth was exceed 9 mm,and the residual compressive stress and dislocation cell structure around the cold-worked holes retarded with the fatigue crack growth rate in the initial and propagation stages,and then improved the whole fatigue life.
出处
《新技术新工艺》
2014年第11期14-17,共4页
New Technology & New Process
关键词
7A12
铝合金
孔挤压
残余应力
疲劳寿命
7A12 aluminum alloy
cold holes expansion
residual stress
fatigue life
