利用磁致伸缩空蚀实验机研究了20SiMn低合金钢在蒸馏水和 3%NaCl溶液中的空蚀行为。利用扫描电镜(SEM)跟踪观察了试样表面的空蚀形貌,测量了静态 和空蚀条件下的极化曲线和腐蚀电位变化，分析了腐蚀因素的影响。结果表明：空蚀使20Si Mn的自腐蚀电位正移近200 mV，使电化学腐蚀速率增大54倍；3％NaCl溶液中最大失重率约 为蒸馏水中的3倍。两种介质中的空蚀形貌相似，空蚀破坏首先在铁素体相以及相界和晶界 发生，在空蚀初期，材料的失重主要来源于铁素体相区的小片剥落，随着空蚀的进行，由于 裂纹的扩展和连接导致材料大块脱落。
The cavitation erosion behavior of 20SiMn low alloy steel in both distilled water and 3%NaCl solution was investigated by using a m agnetostrictive-induced cavitation facility.The micrographs of damaged surfaces were observed by scanning electron microscope (SEM).The role of corrosion was an alyzed by the measurements of polarization curve and free-corrosion potential wi th or without cavitation.The results showed that the cavitation shifted free cor rosion potential to the positive direction by 200 mV.The electrochemical corrosi on rate in the presence of cavitation was 53 times higher than that in absence o f cavitation.The maximum cavitation erosion rate in 3%NaCl solution was almost t hree times as fast as that in distilled water,while the morphologies of damaged surfaces in 3%NaCl solution were similar to that in distilled water.The ferrite area,grain boundaries and ferrite-pearlite phase boundaries were preferential si tes for cavitation attack,which attributed to the low hardness of ferrite phase. The mass loss came from the detachment of small pieces in the ferrite area in th e early stage and from the removal of massive chunks by the propagation and conn ection of cracks in both ferrite and pearlite area in the following test period.
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