【摘要】 采用动电位极化曲线、交流阻抗谱方法研究了激光熔化沉积AerMet100耐蚀超高强度钢在质量分数为3.5%NaCl溶液中的腐蚀电化学行为,采用点蚀失重法研究了热处理对其在酸性FeCl3溶液中点蚀行为的影响。结果表明:激光沉积态AerMet100钢具有较强定向生长特征的细小快速凝固树枝晶组织和优良的耐蚀性,但由于在枝晶尺寸范围的凝固偏析,耐蚀性略低于锻件且纵向电化学耐蚀性能低于横向;经热处理之后,耐蚀性明显改善,耐蚀性能优于锻件且横向电化学耐蚀性略低于纵向。激光沉积态由于耐蚀性元素Cr、Mo、Ni在枝晶间的偏析使得枝晶内组织易发生选择性点蚀,层间热影响区二次枝晶形貌的部分消除使得该区与周围区域形成"区域腐蚀电池"进一步加速了点蚀的发展,抗点蚀性较差,热处理后,其点蚀失重速率降低且与锻件相当。更多还原

【Abstract】 The corrosion electrochemical behavior and pitting corrosion characteristics of laser melting-deposited corrosion-resistant ultrahigh strength steel AerMet100 was studied in 3.5% NaCl solution by potentiodynamic polarization curves and electrochemical impendence spectroscopy(EIS) and acid ferric choloride solution by weight loss method and scanning electron microscopy(SEM) separately.The results show that electrochemical corrosion resistance of as-deposited AerMet100(AD) steel is improved by eliminating dendritic segregation and heterogeneous structure through heat-treatment,which is slightly superior than that of the forged one.Meanwhile,there are different corrosion properties in different directions.And the results also show that preferential pitting corrosion prefers to occur at the selective dendrite cores where depletion of Cr,Mo,Ni compared to dendrite boundaries and "district corrosion battery" set up by heterogeneous structure between inter-layer heat-affected zone and adjacent zone make AD AerMet100 steel poor pitting corrosion resistance,after heat-treatment,the pitting resistance is improved,and the pitting mass loss rate decreases to be similar to that of the forged steel.更多还原