冲击载荷作用下38CrMoAl渗氮钢损伤机理和耐腐蚀性能

为研究38CrMoAl渗氮钢材料在冲击载荷与海洋环境侵蚀共同作用下的损伤机理和耐腐蚀性能，对渗氮处理前后的38CrMoAl钢材料进行了冲击加载试验和腐蚀性能测试。研究发现渗氮38CrMoAl钢材料在高应变率下具有较强的正应变率敏感性。在冲击载荷作用下，试件表面渗氮层出现裂纹，并伴随着渗氮层的部分脆性剥落，但裂纹长度均在500~700 μm，裂纹只在渗氮层中扩展，并没有继续延伸至非渗氮层的金属基体内部。渗氮处理提高了材料表面硬度和强度，但降低了韧性。电化学测试结果表明渗氮处理显著提高了材料的耐腐蚀性能，其自腐蚀电位相对于未渗氮试件由-726.24 mV正移至-174.42 mV。但冲击加载后的渗氮试件由于表面渗氮层的破损，部分金属基体露出并与未发生破坏的表面形成电势差，进而发生较为强烈的电偶腐蚀。扫描开尔文探针测试结果表明，渗氮件表面阴阳极电位差及电位分散程度相对于未渗氮件增大，渗氮件更易发生局部腐蚀。冲击加载改变了渗氮层的表面状态，阴阳极电位差增加，使材料表面腐蚀变得更加不均匀。对试件耐腐蚀性能进行了盐雾试验验证，盐雾试验结果与电化学测试分析结果相一致，在舰载机维护保养中，应关注受冲击部位渗氮层的裂纹检查，并做好相应的防腐处理。

Damage mechanism and corrosion resistance of 38CrMoAl nitrided steel under impact load

To study the damage mechanism and corrosion resistance of 38CrMoAl steel materials under the combined effect of impact load and marine environment erosion, we subjected 38CrMoAl steel materials before and after nitriding to impact loading tests and corrosion performance tests. The studies found that the nitrided 38CrMoAl steel material has strong positive strain rate sensitivity at high strain rates. Under the impact load, cracks appeared on the nitriding layer on the surface of the test piece, accompanied by partial brittle peeling of the nitriding layer, with all crack lengths of 500-700 μm. The cracks only propagated in the nitriding layer without extending to the inside of the metal matrix. Electrochemical test results show that the nitriding treatment significantly improves the corrosion resistance of the material, with its self-corrosion potential shifting from -726.24 mV to -174.42 mV, compared with the non-nitrided specimen. However, due to the damage on the surface nitriding layer after the impact loading, part of the metal matrix is exposed, forming a potential difference with the undamaged surface, which in turn causes strong galvanic corrosion. The scanning Kelvin probe test showed that the anode-cathode potential difference and potential dispersion degree on the surface of nitriding parts are increased compared with the non-nitriding parts, and the nitriding parts are more prone to local corrosion. Impact loading changes the surface state of the nitrided layer, making the surface corrosion of the material more uneven. Finally, the salt spray test was carried out on the test piece, and the results were consistent with those of the electrochemical test. In the maintenance of the carrier-based aircraft, attention should be paid to the crack inspection of the nitrided layer of the impacted part, and corresponding anti-corrosion treatments should be done.