Exceptionally high cavitation erosion and corrosion resistance of a high entropy alloy

Cavitation erosion and corrosion of structural materials are serious concerns for marine and offshore industries. Durability and performance of marine components are severely impaired due to degradation from erosion and corrosion. Utilization of advanced structural materials can play a vital role in limiting such degradation. High entropy alloys (HEAs) are a relatively new class of advanced structural materials with exceptional properties. In the present work, we report on the cavitation erosion behavior of Al_0.1CoCrFeNi HEA in two different media: distilled water with and without 3.5 wt% NaCl. For comparison, conventionally used stainless steel SS316L was also evaluated in identical test conditions. Despite lower hardness and yield strength, the HEA showed significantly longer incubation period and lower erosion-corrosion rate (nearly 1/4th) compared to SS316L steel. Enhanced erosion resistance of HEA was attributed to its high work-hardening behavior and stable passivation film on the surface. The Al_0.1CoCrFeNi HEA showed lower corrosion current density, high pitting resistance and protection potential compared to SS316L steel. Further, HEA showed no evidence of intergranular corrosion likely due to the absence of secondary precipitates. Although, the degradation mechanisms (formation of pits and fatigue cracks) were similar for both the materials, the damage severity was found to be much higher for SS316L steel compared to HEA.     

沙粒粒径和外电位对黄铜腐蚀磨损的影响

利用自制旋转圆盘式空蚀与冲蚀联合作用试验装置,在质量分数为3.5%的Na Cl溶液中试验研究了沙粒粒径和外电位对黄铜腐蚀磨损行为的影响.结果表明:在相同质量分数下,沙粒粒径对黄铜腐蚀性能的影响较小;但黄铜冲刷腐蚀的主要失重方式受沙粒粒径和外电位影响,沙粒粒径较小时,黄铜的流失形式为磨损腐蚀,沙粒粒径较大时,流失形式随外加电位正移由磨损腐蚀转变为磨损.在黄铜冲刷腐蚀中,腐蚀磨损交互作用是引起黄铜流失的主要原因,且以腐蚀对磨损的促进作用更为显著,同时随沙粒粒径的增加及外电位正移,腐蚀磨损交互作用更加突出;基于腐蚀磨损失重率、沙粒尺寸和外电位的冲腐蚀材料流失图表明:在低电位条件下,沙粒粒径对腐蚀磨损总失重率的影响较小,在高外电位条件下,腐蚀磨损总失重率随沙粒粒径的增加急剧增加.     

流体喷射条件下金属材料冲刷腐蚀的研究进展

综述了流体喷射条件下冲刷腐蚀试验装置、冲刷腐蚀机理的研究进展,总结和分析了流速、固相颗粒、攻角等因素对冲刷腐蚀的影响,最后指出了流体喷射下金属材料冲刷腐蚀研究中存在的问题,并展望了流体喷射条件下金属材料冲刷腐蚀的研究方向.     

Effect of compressive stress on cavitation erosion-corrosion behavior of nickel-aluminum bronze alloy

The effect of compressive stress on cavitation erosion-corrosion behavior of nickel-aluminum bronze alloy was investigated, and the results showed that the alloy exhibited selective phase corrosion of eutectoid “α + κ_iii” and its destruction was aggravated with more cavitation mass loss up to 1.74 times of the specimen without stress. It was mainly owing to the enhanced corrosion-induced erosion caused by compressive stress, which led to lattice distortion of the alloy and the resulting accelerated selective phase corrosion with increasing surface roughness, and then intensified the synergistic effect of electrochemical corrosion and mechanical erosion.     

时效处理温度对17-4PH铸造不锈钢在稀硫酸料浆中的冲刷腐蚀性能影响

采用自制料浆罐式冲刷腐蚀试验机研究了在含固相颗粒稀硫酸料浆介质中,时效处理温度对17-4PH铸造不锈钢的组织、硬度及冲刷腐蚀性能的影响,分析了不同时效温度下冲击速度对17-4PH铸造不锈钢冲刷腐蚀行为的影响,观察了冲刷腐蚀表面形貌,探讨了冲刷腐蚀机理.结果表明:17-4PH铸造不锈钢经固溶处理及460℃左右时效处理后其硬度达到最大值;经时效处理后17-4PH铸造不锈钢冲刷腐蚀特征表现为纯冲刷磨损为主,腐蚀为辅,腐蚀促进磨损;在冲刷速度较低时,时效处理温度对17-4铸造不锈钢的冲刷腐蚀率影响不大,而在冲刷速度较高时,460℃左右时效处理后,由于析出大量细小弥散分布的ε-Cu沉淀相而具有最佳的沉淀强化效果,抗冲蚀腐蚀性能最佳;在不降低耐腐蚀性能的前提下,利用沉淀析出硬化是一种提高材料抗冲刷腐蚀性能的有效方法.