Li Xiangxue, Shi Chengcheng, Han Guofeng, Liu Huan, Li Xiaofei, Liu Rui
School of Mechanical Engineering, Shandong University of Technology, Zibo 255000, China.
National Key Lab for Remanufacturing, Beijing 100072, China.
Materials (Basel). 2024 May 28;17(11):2602. doi: 10.3390/ma17112602.
A solid-state repair technique based on surface friction welding is investigated in depth to achieve excellent mechanical properties of damaged 7A52 aluminum alloy. The results show that the yield strength and tensile strength along the repair direction are 436 MPa and 502 MPa, respectively, at a rotational speed of 1400 rpm and a travel speed of 300 mm/min, which are about 157.9% and 129.7% of those before the defects were repaired, respectively, while the elongation is 17.2% compared to the base material. Perpendicular to the repair direction, the yield strength and tensile strength are 254 MPa and 432 MPa, which are 111.4% and 129.7% of those before the defects were repaired, respectively, while the elongation is 11.8% compared to the base material. The mechanical properties of the repaired areas are still improved compared to those of the defect-free sheets. On the one hand, this is attributed to the dynamic recrystallization of the nugget zone due to the thermo-mechanical coupling, resulting in the formation of a fine, equiaxed grain structure; on the other hand, the precipitated MgSi phase, which is incoherent within the base material, transforms into the Al(Fe, Mn)Si phase, as well as the precipitation of the AlMn phase and η' phase, resulting in the enhancement of the properties. The material fracture at the junction of the nugget zone and the heat-affected zone occurs after repair, which is attributed to the significant difference in the texture of the nugget zone and the heat-affected zone, as well as to the stress concentration at the junction.
为了使受损的7A52铝合金获得优异的力学性能，对基于表面摩擦焊接的固态修复技术进行了深入研究。结果表明，在转速为1400 rpm、行进速度为300 mm/min时，沿修复方向的屈服强度和抗拉强度分别为436 MPa和502 MPa，分别约为修复缺陷前的157.9%和129.7%，而伸长率与母材相比为17.2%。垂直于修复方向，屈服强度和抗拉强度分别为254 MPa和432 MPa，分别为修复缺陷前的111.4%和129.7%，而伸长率与母材相比为11.8%。与无缺陷板材相比，修复区域的力学性能仍有所提高。一方面，这归因于热机械耦合导致的熔核区动态再结晶，形成了细小的等轴晶粒结构；另一方面，母材中不连续的析出MgSi相转变为Al(Fe,Mn)Si相，以及AlMn相和η'相的析出，导致性能增强。修复后，在熔核区与热影响区的交界处发生材料断裂，这归因于熔核区与热影响区织构的显著差异以及交界处的应力集中。
