【摘要】 通过对7A52铝合金进行大量的搅拌摩擦焊接试验,对焊缝的宏观组织、微观组织及显微硬度进行分析。焊缝可分为热影响区、热机影响区和焊核等三个区域。其中,焊核为明显的再结晶等轴晶粒,晶粒明显细化;热机影响区出现了晶粒粗化现象,由母材的细纤维组织变形为具有一定弧度的弯曲粗纤维组织;热影响区的晶粒与母材相似,但出现了晶粒粗化现象。沿焊缝横截面的显微硬度的分布呈高-低-高-低-高的趋势,其中焊缝顶部的硬度达到了母材的硬度,硬度最低处位于前进侧的热影响区区域。更多还原

【Abstract】 The macro-and micro-structures and micro-hardness of friction stir welding of 7A52 aluminum alloy were investigated.The welded joint of aluminum alloy 7A52 can be divided into three regions as follows: heat affected zone(HAZ),thermo-mechanically affected zone(TMAZ) and weld nugget.The weld nugget had a dynamic recrystallized,fine isometric crystal structure.The TMAZ had a highly deformed structure,and the grains were curved strip and larger than that in the weld nugget.The HAZ had similar structure to the base metal,but the size of grains was larger than that in the base metal.Distribution of microhardness in the cross section presented a trend of high-low-high-low-high.The base metal outside the weld show the maximal hardness,and the top of the weld nugget has the same hardness as the base metal,the lowest hardness was in the advancing side in the HAZ.更多还原