论文部分内容阅读
采用超音速微粒轰击(SFPB)和表面机械滚压处理(SMRT)相结合的混合表面纳米化(HSNC)方法在2A14铝合金表面制备出梯度纳米结构(GNS)表层,之后进行了搅拌摩擦焊(FSW)。利用OM、SEM和TEM对比研究了HSNC样品和原始样品FSW焊缝的微观组织和断裂形貌。结果表明,GNS表层以类似“S”线复杂形式分布在HSNC样品的热机影响区(TMAZ)和焊核区(NZ)中,形成了纳米层区(NLZ);原始样品显微硬度最低处和断裂位置均发生在前进侧的TMAZ,HSNC样品显微硬度最低处和断裂位置均发生在NZ;HSNC样品的抗拉强度比原始样品提高了6.4%,延伸率比原始样品提高了14.1%,两者的断裂方式均为韧性断裂,但原始样品断口形貌为非等轴韧窝和撕裂韧窝,HSNC样品断口形貌为等轴韧窝。分析表明,由于纳米晶的优异性能,NLZ在提高焊缝强度的同时提高了塑性变形能力。
A graded nanostructured (GNS) surface layer was prepared on the surface of 2A14 aluminum alloy by a hybrid surface nanocrystallization (HSNC) method with a combination of SFPB and SMRT. Afterwards, friction stir welding FSW). The microstructure and fracture morphology of FSNC weld between HSNC sample and original sample were studied by OM, SEM and TEM. The results show that the surface layer of GNS is distributed in the heat affected zone (TMAZ) and the nugget zone (NZ) of the HSNC sample in a complex pattern similar to the “S” line, forming the nanolayer zone (NLZ). The original microhardness And the location of the fracture occurred on the front side of the TMAZ, HSNC sample at the lowest microhardness and fracture location occurred in the NZ; HSNC sample tensile strength was 6.4% higher than the original sample, elongation than the original sample increased by 14.1% , The fracture modes of both are ductile fracture, but the fracture morphology of the original sample is non-equiaxed dimple and torn dimple, and the fracture morphology of HSNC sample is equiaxed dimple. The analysis shows that due to the excellent properties of nanocrystals, NLZ improves the plastic deformation capacity while increasing the weld strength.