Effect of solution treatment on the microstructure and properties of low-Ni duplex stainless steel

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• 作者：YANG ZhenSHEN PengYAN HaitaoZHAO JinYANG Zhichun
• 会议时间：2013-06-01
• 关键词：low-Ni duplex stainless steel ; solution treatment ; microstructure ; mechanical properties ; pitting corrosion
• 母体文献：第五届宝钢学术年会论文集
• 会议名称：第五届宝钢学术年会
• 会议地点：上海
• 主办单位：中国金属学会
• 语种：chi

摘要

The effect of different solution treatment processes on the microstructure,mechanical properties and corrosion resistance of low-Ni duplex stainless steel was investigated.At the same time,the performances of the hot rolled low-Ni duplex stainless samples were tested.The difference of performances of the low-Ni duplex stainless steel hot-rolled samples and the solution samples' was compared and the reasons were explained.The results were as follows : ①The samples after solution treatment of (1 020 - 1 120℃ ) × 10 min,its volume fraction of ferrite phase increased,and its tensile strength and impact energy and Rockwell hardness decreased with the increasing of annealing temperature in the range of 1 020 - 1 120℃.However,in the range of 1 020 - 1 120℃,its pitting corrosion rate changed very little.②The samples after solution treatment of 1 050℃ × (2 - 32) min,its volume fraction of ferrite phase increased,and its tensile strength,impact energy,Rockwell hardness and the pitting corrosion rate changed very little with the increasing of the holding time in the range of 2 - 32 min.③Comparing with the hot rolled samples and the solution treatment samples,the tensile strength and hardness of the solution treatment samples was higher than the solution treatment samples ',this because of residual stresses and the work hardening existed in the hot rolled samples and the grain size of hot rolled samples was smaller.④The hot rolled samples and solution treatment samples were tested by scanning electron microscopy ( SEM),it can be seen that: The Cr2N precipitate existed in the hot rolled samples,while the solution treatment samples had not Cr2N precipitate,this was one of the reason that the impact resistance and corrosion resistance of the hot rolled samples was worse than the solution treatment samples '.⑤The changing tendency of ferrite volume fraction of the solution treatment low-Ni duplex stainless steel samples agreed well with the calculated results of Thermo-calc.However,the values of ferrite volume fraction by Thermo-calc were much lower than the values determined by FERITSCOPE FMP30 instrument at different solution temperature.This was because Thermo-calc described thermodynamic equilibrium conditions while the steels could never be in true equilibrium.