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焊接模式对电弧增材制造316不锈钢组织及力学性能的影响

Effects of different welding modes on microstructure and mechanical properties of 316 stainless steel by wire arc additive manufacturing

  • 摘要: 基于冷金属过渡、冷金属过渡-脉冲以及直流脉冲三种焊接模式,开展了316不锈钢单道多层薄壁试样的电弧增材制造,并对试样进行了组织与性能的对比分析. 结果表明,三种模式下成形构件均无塌陷和宏观气孔现象,凝固组织以柱状树枝晶为主,并伴随有大量的二次枝晶、胞状晶,通过金相观察和背散射电子衍射技术发现,组织表现出强<001>//z织构,构件中段稳态区的平均枝晶间距随不同焊接模式下的热输入变化而变化:由小到大依次为CMT—CMT-P—DC-P. 通过X射线衍射和扫描电镜-能谱分析确定基体组织为γ-Fe(Cr0.19Fe0.7Ni0.11),基体间网状组织为残余δ-Fe. CMT-P模式下的构件强度最高,屈服强度达 237 MPa,抗拉强度达555 MPa,平均硬度值达209 HV0.3, DC-P模式构件的断后伸长率最高达52%.

     

    Abstract: This study focused on the additive manufacturing of single-pass multi-layer thin-walled samples using 316 stainless steel. It explored three welding modes: cold metal transfer (CMT), cold metal transfer-pulse (CMT-P), and direct current-pulse (DC-P), and conducted a comparative analysis of the microstructure and mechanical properties of the samples. Under the three modes of formation, the resulting components exhibited no collapse or macroscopic porosity. The solidified structure consists predominantly of columnar dendritic crystals, along with a significant presence of secondary dendrites and cellular crystals. Upon conducting metallographic observation and utilizing electron back scatter diffraction (EBSD) technology, it was determined that the structure demonstrates a pronounced <001>//z texture. The average spacing of dendrites in the steady-state zone of the component exhibits variation based on the heat input across different welding modes, with the pattern being CMT < CMT-P < DC-P. The matrix structure was identified as γ-Fe(Cr0.19Fe0.7Ni0.11) using X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, while the interstitial network structure was found to be residual δ-Fe. In CMT-P mode, the component exhibits the highest strength, characterized by a yield strength of 237 MPa, a tensile strength of 555 MPa, and an average hardness value of 209 HV0.3. In the DC-P mode, the component exhibits the highest elongation at break, reaching 52%.

     

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