低碳钢薄板钨极氩弧焊与搅拌摩擦焊接头微观组织形态对比研究

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中图分类号：TG44

Comparative study on microstructure morphology of low carbon steel thin sheet joints welded by gas tungsten arc welding and friction stir welding

BIYanping，WANGGuofu，WANGHuiyuan，LIUManyu （Harbin Well Welding Co.，Ltd.，Harbin 15006O，China）

Abstract： This study systematically compares the microstructural morphology differences in the joints of 3 mm thick Q235 low-carbon steel thin plates welded by Gas Tungsten Arc Welding（GTAW）and Friction Stir Welding（FSW），aiming to reveal the microstructural evolution laws ofboth processes under identical heat input conditions.Through controlled experiments with equivalent heat input parameters，combined with ultra-depth microscopy and Electron Backscater Diffraction（EBSD）techniques，the weld surface morphology，grain size， and orientation distribution characteristics were analyzed. The results indicate that the FSW nugget zone forms ultrafineequiaxed grains through dynamic recrystalization，exhibiting significantly higher grain refinement than the mixed microstructure in the GTAW weld zone.The GTAW heat-afected zone（HAZ）generates network-like acicular ferite，while the FSW thermo-mechanically affected zone retains partially recrystallized grains，highlighting the diferences between fusion welding phase transformationand solid-state welding plastic deformation mechanisms.Furthermore，FSW welds exhibit keyhole defects and asymmetric flash on the surface，along with groove-like defects on the backside，whereas GTAW welds show uneven reinforcement distribution and greater surface quality fluctuations. Thestudy demonstrates that FSW achievesultrafine grain refinement through mechanical stirring and coupled thermal-mechanical efects but requires processoptimization to reduce defects. In contrast，GTAW welding is limited by molten pool solidification behavior，resulting in lower microstructural homogeneity.

Key Words：Gas Tungsten Arc Welding；Friction Stir Welding；Microstructure；EBSD；Low Carbon Steel Thin Sheet

0 前言

焊接技术作为制造业基础工艺，其质量直接影响构件的结构强度和使用寿命。（剩余5905字）