多层激光熔覆对30CrMnSiNi2A高强钢组织与性能的影响  

Influence of Multilayer Laser Cladding on the Microstructure and Properties of 30CrMnSiNi2A Steel Substrate

作　　者：庞小通 姚成武[1] 龚群甫[2] 王志杰 李铸国[1] Pang Xiaotong;Yao Chengwu;Gong Qunfu;Wang Zhijie;Li Zhuguo(Shanghai Key Laboratory of Materials Laser Processing and Modification,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;PLA 4724 Plant,Shanghai 200436,China)

机构地区：[1]上海交通大学材料科学与工程学院上海市激光制造与材料改性重点实验室,上海200240 [2]中国人民解放军第四七二四工厂,上海200436

出　　处：《中国激光》2021年第6期69-79,共11页Chinese Journal of Lasers

基　　金：上海市军民融合专项(JMRH-2018-1033)。

摘　　要：在30CrMnSiNi2A高强钢基体上进行多层激光熔覆,研究各层熔覆热循环对基体组织与力学性能的影响。结果表明:在组织方面,熔覆盖面层时均对基体重新淬硬,由于已沉积熔覆层会吸收激光热量,故基体淬硬深度会随着层数的增加而逐渐减小,淬硬深度减小至对基体不能完全奥氏体化时,出现了不完全淬硬现象;继续增加熔覆层数,熔覆层不再重新淬硬基体,产生了回火作用。多层熔覆时每一层均对基体有回火作用,随着层数的增加,基体马氏体板条束间残余奥氏体首先分解,接着碳化物逐渐析出,马氏体板条粗化变宽、块状化,直至板条状马氏体特征消失,完全转变为索氏体组织。在力学性能方面,随着层数增加,基体热影响区试样变化趋势为抗拉强度逐渐降低、冲击韧性逐渐升高。由于激光快速加热,首层熔覆对基体回火残余奥氏体分解不明显,次层或后续层熔覆对基体残余奥氏体产生明显的分解作用,故残余奥氏体相减少,造成拉伸延伸率、冲击韧性均略有降低。随着熔覆层数增加,基体热影响区拉伸延伸率增加,拉伸断裂沿高温回火区启裂、扩展;熔覆层数继续增加,直至对基体产生不完全淬火时,拉伸断裂可分别在不完全淬火区、高温回火区多点启裂、扩展,拉伸塑性变形协调性下降,造成基体热影响区试样延伸率显著下降。Objective Compared with conventional welding repair methods,laser cladding,an advanced surface modification technology,uses nonequilibrium processing conditions,such as rapid heating and cooling,to fabricate similar alloy compositions on the surface of high-strength steel components.The coating can exhibit refined grains and high dislocation density to achieve high strength and ductility of the repair zone.Therefore,it is a potential for the laser repair of high-strength steel surfaces.Traditional welding methods are used to repair high-strength steel using multilayer and multipass repair welding.Multiple welding thermal cycles induce coarse grains in the heat-affected zone(HAZ),which can lead to significant embrittlement and poor impact toughness of the high-strength steel substrate.Similar to traditional welding,the multilayer and multipass thermal cycles in laser cladding can have multiple tempering effects on the substrate hardened zone,which can lead to grain coarsening and strength softening of the substrate in HAZ.For the multilayer and multipass laser repair of high-strength steel components,in addition to the effective control of the microstructure and performance of the cladding layer,the softening problem of HAZ in the high-strength substrate and the deterioration of mechanical properties(i.e.,low strength and poor elongation)must be overcome.Therefore,in this study,the variation trends of the microstructure evolution and mechanical properties of HAZ in the 30 CrMnSiNi2 A substrate were shown to be beneficial in controlling the strength and ductility of the repaired high-strength steel parts.Methods Multilayer laser cladding 30 CrMnSiA powders were processed on thick 30 CrMnSiNi2 A steel plates with geometric sizes of 120 mm×60 mm×10 mm using the 8-kW semiconductor laser(Laserline LDF-8000-60).The laser cladding parameters were as follows:2100-W laser power,7.3-mm beam diameter,9-mm/s laser scanning speed,10-g/min powder feed rate,10-L/min powder feed gas flow,20-L/min coaxial shielding gas flow,and0

关 键 词：激光技术 激光熔覆 热循环 热影响区 微观组织 力学性能 

分 类 号：V261.8[航空宇航科学与技术—航空宇航制造工程]