316不锈钢激光焊接中离焦量对热裂纹的影响
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摘要
采用最大平均功率为500 W的脉冲激光焊机开展了316不锈钢焊接试验,通过测试表面形貌、微观组织、显微硬度及能谱(EDS)等,分析了离焦量对焊缝组织和热裂纹的影响。研究结果表明,在其他焊接参数不变的条件下,离焦量增大时焊缝组织逐渐细化和致密,热裂纹倾向性逐渐减小。焊缝熔深和熔宽均随离焦量的增大而减小,但宽深比增大,当宽深比大于7.5时焊接热裂纹彻底消失。增大离焦量改变了激光能量的分布状态,导致焊缝凝固过程中S、P等元素向熔池表面偏析,消除了焊缝凝固后期液膜及低熔点组织的不利影响,有效控制了脉冲激光焊接316不锈钢热裂纹的产生。
316 stainless steel welding experiments were carried out with a low power pulsed laser welding machine.Based on the surface morphology,microstructure,microhardness and energy dispersive spectrum(EDS),the effect of defocusing amount on the weld structure and hot cracking was analyzed.The results show that with the increase of defocusing amount,the weld microstructure is gradually refined and compact,and the tendency of hot cracking decreases gradually.With the increase of defocusing amount,the weld penetration and weld width reduce,but the width to depth ratio increases.When the width to depth ratio is greater than 7.5,the welding hot cracking completely disappears.Adjusting the defocusing amount changes the distribution of laser energy,which leads to the segregation of S,P and other elements to the surface during solidification.So the defocusing amount can effectively control the welding hot cracking of 316 stainless steel.
316 stainless steel welding experiments were carried out with a low power pulsed laser welding machine.Based on the surface morphology,microstructure,microhardness and energy dispersive spectrum(EDS),the effect of defocusing amount on the weld structure and hot cracking was analyzed.The results show that with the increase of defocusing amount,the weld microstructure is gradually refined and compact,and the tendency of hot cracking decreases gradually.With the increase of defocusing amount,the weld penetration and weld width reduce,but the width to depth ratio increases.When the width to depth ratio is greater than 7.5,the welding hot cracking completely disappears.Adjusting the defocusing amount changes the distribution of laser energy,which leads to the segregation of S,P and other elements to the surface during solidification.So the defocusing amount can effectively control the welding hot cracking of 316 stainless steel.
引文
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[4]杨文斗.反应堆材料学[M].北京:原子能出版社,2006.
[5]刘明.压水堆燃料棒端塞焊缝超声波无损检测装置研制[D].郑州:郑州大学,2007.
[6]朱荣华.409L不锈钢管激光焊接温度场及应力应变场分析[D].哈尔滨:哈尔滨理工大学,2008.
[7]CUI L,LI Xiaoyan,HE Dingyong,et al.Microstructure investigation of Nd:YAG laser welded5A90aluminum-lithium alloys[J].Transactions of the China Welding Institution,2010,31(9):77-78.
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