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不同焊接方法下1000 MPa级熔敷金属组织及强韧性

Microstructure and mechanical properties of 1000 MPa grade deposit metals under different welding methods

  • 摘要: 采用熔化极活性气体保护焊(MAG)和钨极氩弧焊(TIG)制备1000 MPa级Ni-Cr-Mo系熔敷金属.利用光学显微镜(OM)、配备能谱(EDS)的扫描电镜(SEM)、透射电镜(TEM)对熔敷金属微观组织进行表征;通过拉伸、示波冲击、硬度试验等对熔敷金属力学性能进行测试,探讨焊接方法对1000 MPa级Ni-Cr-Mo系熔敷金属强韧性影响.结果表明,不同焊接方法制备的熔敷金属末道焊组织均由板条马氏体、板条贝氏体、联合贝氏体和残余奥氏体组成,其中TIG熔敷金属以板条马氏体为主,MAG熔敷金属以贝氏体类组织为主;MAG熔敷金属柱状晶宽度大于TIG熔敷金属,且MAG熔敷金属中非金属夹杂数量和密度均大于TIG熔敷金属;组织不同导致力学性能差异较大,两者抗拉强度达到1080 MPa,屈服强度存在差异:TIG ReL = 1008 MPa,MAG ReL = 829 MPa;AKV(−50 ℃)差异明显:TIG AKV = 95 J,MAG AKV = 51 J,TIG熔敷金属强韧匹配更佳.

     

    Abstract: The 1,000 MPa grade Ni-Cr-Mo deposited metal was prepared by metal active-gas welding and tungsten inert gas welding respectively. Optical microscope (OM), scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM), were used to characterize the microstructure of the deposited metal. The mechanical properties of the deposited metal were evaluated through tensile testing, instrumented charpy impact testing, and hardness testing to investigate the influence of welding methods on the strength and toughness of 1 000 MPa-grade Ni-Cr-Mo deposited metal. The results show that the final weld microstructure of the deposited metal prepared by different welding methods consists of lath martensite, lath bainite, Granular bainite and retained austenite. TIG deposited metal is mainly lath martensite, MAG deposited metal is mainly bainite-like microstructure. The width of columnar crystals in MAG deposited metal is larger than that in TIG deposited metal, and the number and density of non-metallic inclusions in MAG deposited metal are larger than those in TIG deposited metal; The different microstructure led to significant differences in mechanical properties, both tensile strength reached 1 080 MPa, their yield strengths differed substantially: where TIG 1,008 MPa, MAG 829 MPa; AKV (−50 ℃) difference is obvious: TIG 95 J, MAG 51 J, TIG deposited metal strength and toughness match better.

     

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