In this study, different welding param eters were selected to investigate the effects of heat-in put on the microstructure and corrosion resistance of the friction stir welded high nitrogen stainless steel joints. The...In this study, different welding param eters were selected to investigate the effects of heat-in put on the microstructure and corrosion resistance of the friction stir welded high nitrogen stainless steel joints. The results show ed that, the welding speed had major influence on the duration at elevated tem perature rather than the peak tem perature. The hardness distribution and tensile properties of the nugget zones (NZs) for various joints were very similar while the pitting corrosion behavior of various NZs showed major differences. Large heat-input resulted in the ferrite bands being the pitting location, while tool wear bands were sensitive to pitting corrosion in the low heat-input joints. Cr diffusion and tool wear were the main reasons for pitting. The mechanisms of pitting corrosion in the NZs were analyzed in detail.展开更多
In this paper, microstructure and mechanical properties of welding metals in 610 MPa high strength low alloy （HSLA） were studied after high-heat-input welding. Both the base material and the weld joint proved excell...In this paper, microstructure and mechanical properties of welding metals in 610 MPa high strength low alloy （HSLA） were studied after high-heat-input welding. Both the base material and the weld joint proved excellent strength and toughness by vibratory electrogas arc （VEGA） welding under 90 to 100 kJ/cm heatinput. The heat-affected zone （HAZ） was comprised of fine-grain zone （FGZ） and coarse-grain zone （CGZ）, which characterizes fine granular structure and lathing-bainite substructure, It has found that large quantity of dispersed TiN and M23E6 precipitates restrain structure growing in HAZ and strengthen the weldment together with dislocations in the welded joint.展开更多
基金supported financially by the National Natural Science Foundation of China (Nos. 51671190 and 51471171)
文摘In this study, different welding param eters were selected to investigate the effects of heat-in put on the microstructure and corrosion resistance of the friction stir welded high nitrogen stainless steel joints. The results show ed that, the welding speed had major influence on the duration at elevated tem perature rather than the peak tem perature. The hardness distribution and tensile properties of the nugget zones (NZs) for various joints were very similar while the pitting corrosion behavior of various NZs showed major differences. Large heat-input resulted in the ferrite bands being the pitting location, while tool wear bands were sensitive to pitting corrosion in the low heat-input joints. Cr diffusion and tool wear were the main reasons for pitting. The mechanisms of pitting corrosion in the NZs were analyzed in detail.
文摘In this paper, microstructure and mechanical properties of welding metals in 610 MPa high strength low alloy （HSLA） were studied after high-heat-input welding. Both the base material and the weld joint proved excellent strength and toughness by vibratory electrogas arc （VEGA） welding under 90 to 100 kJ/cm heatinput. The heat-affected zone （HAZ） was comprised of fine-grain zone （FGZ） and coarse-grain zone （CGZ）, which characterizes fine granular structure and lathing-bainite substructure, It has found that large quantity of dispersed TiN and M23E6 precipitates restrain structure growing in HAZ and strengthen the weldment together with dislocations in the welded joint.
文摘通过焊接热模拟研究了在超大线能量下焊接时Al元素、Mg元素和Ti元素含量对EH36高强船板钢热影响区粗晶区组织、性能的影响规律,采用Thermo-Calc热力学计算与SEM,EDS测试相结合的方法揭示了Al元素、Mg元素和Ti元素含量与母材中氧化物类型、尺寸、数量及粗晶区相变的关系.结果表明,Al_(2)O_(3)无法诱导针状铁素体相变,当Al元素质量分数低于0.005%时,钢中可形成Mg元素、Ti元素或其复合氧化物,可促进粗晶区针状铁素体相变.Mg元素和Ti元素联合添加时,当Mg元素质量分数由0.0042%降低为0.0013%,氧化物类型由MgO转变为Mg_(2)TiO_(4),经统计20个视场内的氧化物数量由408个提高到503个,平均直径由1.37μm减小到1.10μm,显著提高了非均匀形核的比表面积,抑制了晶界铁素体的形成,使t8/5=300 s时粗晶区热模拟试样-20℃冲击吸收能量由43 J提升到127 J.
