QPQ工艺对低碳钢显微结构及极化性能的影响  

Influence of QPQ Salt-bath Nitriding and Post-oxidation Process on Microstructure and Electrochemical Polarization Properties of Low Carbon Steel

作　　者：张磊[1] 罗德福[1] 陈君[1] 

机构地区：[1]西华大学材料科学与工程学院,四川成都610039

出　　处：《西华大学学报（自然科学版）》2017年第5期102-107,共6页Journal of Xihua University:Natural Science Edition

基　　金：国家自然科学基金项目(51077730)

摘　　要：用QPQ盐浴复合处理技术对低碳钢进行表面改性处理,对处理后的低碳钢表面进行系统表征。结果表明:QPQ氮化处理后低碳钢试样表面从外至内由Fe_3N/Fe_(24)N_(10)/FeN_(0.0939)组成,氧化处理后,试样表面从外至内的组成物变成了Fe_3O_4/Fe_2N/α-Fe,氧化处理使外层氮化层由Fe_3N转变成Fe_3O_4/Fe_2N,内层氮化层由Fe_(24)N_(10)/FeN_(0.0939)转变成α-Fe;氧化处理后,分别在外层氮化层和内层氮化层上出现大量的显微裂纹和孔状结构;与只进行过氮化处理的试样相比,氧化处理后试样的表面硬度降低了50~100 HV0.025。通过极化曲线可以看出,与氮化试样相比氧化处理后腐蚀电流密度下降了0.055μA.cm^(-2),腐蚀电位也降低了79 mV。这表明氧化处理能有效提升试样的耐腐蚀能力,而氧化过程中产生的表面缺陷可能导致了腐蚀电位下降。Low carbon steel was surface modified by the quench - polish - quench salt bath treatment process （QPQ）. The modi-ied surface was systematically characterized. The results reveal that the nitrided sample surface consists of Fe3 N/Fe24 N10/FeN0.0939 , while the post - oxidized sample surface consists of Fe3O4/Fe2N/ a - Fe. The Fe3N in the outer - layer and Fe24N 10/F e N0.0939 in the sub - layer were transformed as Fe3O4/Fe2N and a - Fe, respectively, after conducting post - oxidation process. After post - oxidi-zing ,many cracks and pores were observed on the outer - layer and sub - layer. The hardness profile of post - oxidized sample de-creased about 50 ？100 HV0 025 with comparison to nitrided sample. The polarization curves results reveal that the corrosion current den-sity （ icon ） of post - oxidized sample decreased about 0. 055 jjlA . cm 2 w ith comparison to n itr id e d sample, indica tin g an improvement of corrosion resistance. However, the corrosion potential （E C0II） decreased about 79 mV, which may be caused by the cracks and pores ormed on the compound layer by post - oxidizing process.

关 键 词：低碳钢 QPQ盐浴处理 显微结构 极化曲线 腐蚀电流密度 

分 类 号：TG156.3[金属学及工艺—热处理]