【摘 要】
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High-strength pipeline steel was subjected to friction stir welding (FSW) at rotation rates of 400-700 rpm,and the grain refinement mechanism of the nugget zone (NZ) was determined.The thermo-mechanical process during FSW in the NZ was simulated by multi-
【机 构】
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State Key Laboratory of Rolling and Automation,Northeastern University,No.3 Wenhua Road,Shenyang 110
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High-strength pipeline steel was subjected to friction stir welding (FSW) at rotation rates of 400-700 rpm,and the grain refinement mechanism of the nugget zone (NZ) was determined.The thermo-mechanical process during FSW in the NZ was simulated by multi-pass thermal compression,thereby achieving the austenitic non-recrystallization temperature (Tnr).The austenitic non-recrystallization in the NZ at the lowest rotation rate of 400 rpm caused a significant grain refinement.Furthermore,the reduced rotation rate also resulted in the formation of a high ratio of island-like martensite-austenite (M-A) con-stituent.The toughness of the NZs was enhanced as the rotation rate decreased,which is attributed to the fine effective grains and homogeneously distributed fine M-A constituents dramatically inhibiting crack initiation and propagation.
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