焊前混合表面纳米化对2A14铝合金搅拌摩擦焊接头微观组织和力学性能的影响

发布时间：2018-08-03 09:21

【摘要】：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。
[Abstract]:The gradient nanostructure (GNS) surface was prepared on the surface of 2A14 aluminum alloy by mixed surface nanocrystalline (HSNC) method combined with supersonic particle bombardment (SFPB) and surface mechanical rolling treatment (SMRT). Then the (FSW). Was welded by friction stir welding. The microstructure and fracture morphology of FSW welds of HSNC and original samples were studied by OMG SEM and TEM. The results show that the surface layer of GNS is distributed in the (TMAZ) of the heat-affected zone and the (NZ) in the nugget zone of the HSNC sample in the complex form similar to "S" line. The lowest microhardness and fracture location of the original (NLZ); samples in the nano-layer region occurred at the lowest microhardness and fracture locations of the (NLZ); samples on the forward side. The tensile strength of the (NLZ); samples was increased by 6.4and extended. The rate of fracture is 14.1% higher than that of the original sample. The fracture mode of both is ductile fracture. But the fracture morphology of the original sample is non-equiaxed dimple and tear dimple HSNC sample fracture morphology is equiaxed dimple. The results show that because of the excellent properties of nanocrystals, NLZ not only increases the weld strength, but also improves the plastic deformation ability.
【作者单位】：火箭军工程大学;西安理工大学材料科学与工程学院;中国航天科技集团长征机械厂;
【基金】：国家自然科学基金项目No.51275517 陕西省科技计划项目No.2009K06-22 西安理工大学特色研究项目No.2014TS002~~
【分类号】：TG174.4;TG453.9

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