超级马氏体不锈钢的等离子渗氮和氮碳共渗

Plasma Nitriding and Nitrocarburising of a Supermartensitic Stainless Steel

超级马氏体不锈钢(SMSSs)是典型的新一代13%Cr马氏体钢,含碳量较低,并含镍和钼,故具有更好的可焊性和低温韧性。研究表明,不锈钢低温等离子渗氮或氮碳共渗可形成硬的表层从而提高耐磨性。本文对SMSS试样分别在400℃、450℃和500℃进行了等离子渗氮和氮碳共渗,并对处理后的SMSS试样分别采用光学显微镜、显微硬度、XRD和干磨损试验进行了表征。X射线衍射分析证明,氮化铬含量随着渗氮和氮碳共渗温度的升高而增加,也显示出铁和铬的碳化物含量随着处理温度的升高而增加。不同温度下处理后的试样均随着处理温度的升高,磨损体积减小、耐磨性提高。对经等离子处理和未处理的试样所观察到的主要磨损机制都是凿削磨损。

Supermartensitic stainless steels （SMSSs） are a new generation of the classic 13%Cr martensitic steels, lower in carbon and with additional alloying of nickel and molybdenum offering better weldabilty and low temperature toughness .Several works have shown that plasma nitriding and nitrocarburising of stainless steels at low temperatures produces a hard surface layer which results in increased wear resistance .In this work, SMSS samples were plasma nitrided and nitrocarburised at 400, 450 and 500 ℃.The plasma treated SMSS samples were characterised by means of optical microscopy , microhardness , X-ray diffraction and dry wear tests .The thickness of the layers produced increases as temperature is raised , for both plasma nitriding and nitrocarburising .X-ray diffraction demonstrates that the chromium nitride content grows with temperature for nitriding and nitrocarburising , which also showed increasing content of iron and chromium carbides with temperature .After plasma treating , it was found that the wear volume decreases for all temperatures and the wear resistance increased as the treatment temperature was raised .The main wear mechanism observed for both treated and untreated samples was grooving abrasion .