摘要
测试了搅拌摩擦焊接后2A97铝-锂合金薄板沿焊缝中心线以及垂直于焊缝方向的疲劳裂纹扩展速率,并且采用金相显微镜、扫描电镜、EBSD设备对焊缝组织特征以及断口形貌进行了观察。结果表明,搅拌摩擦焊后,无论是垂直焊缝还是沿焊缝宽度中线,疲劳裂纹的扩展方向都与预制裂纹方向一致,没有发生显著改变;与母材相比,搅拌摩擦焊接后两种类型的试样在稳态扩展区间内的扩展速率与母材的相当,但进入失稳扩展阶段的应力强度因子范围△K值较低,△K值分别为:母材,33.2 MPa·m^(1/2);裂纹平行焊缝试样,20.3 MPa·m^(1/2);裂纹垂直焊缝试样,22.3MPa·m^(1/2)。搅拌摩擦焊接过程中带来的组织改变是导致耐损伤性能恶化的主要原因。
Fatigue crack growth tests were carried out on the cracks growing rates along anu perpendicular to the weld centre line of 2A97 Ai-Li alloy sheet after friction stir weld. Optical microscope, SEM, and EBSD were used to observe the microstructure of weld zone and frac- ture surface of fatigue samples. It is found that the propagation directions of the cracks in both samples do not change obviously during the test. The crack growth rates of both types of welded samples are similar to the matrix during the stable spread region, but the threshold values of reaching unstable region are different. The values of the matrix, the samples with crack along weld centre line, and the samples with crack perpendicular to the weld region are 33.2 MPa·m^1/2 ,20.3 MPa·m^1/2 ,22.3 MPa·m^1/2,respectively. The main factor which leads to the damage resistance deterioration is the microstrcture change during friction stir weld.
出处
《轻合金加工技术》
CAS
北大核心
2018年第1期53-60,共8页
Light Alloy Fabrication Technology
基金
国家自然科学基金(51474195)
