TD法盐浴渗钒层初期生长表面形貌的研究

Study on Growth of Vanadium Carbide Coating at Initial Stage of Salt Bath Vanadizing Process

在不同温度下对T12钢基体进行不同时间的盐浴渗钒处理,采用扫描电镜、电子探针和XRD等分析手段,分析了渗钒层初期生长的表面形貌演变过程,并对比了国产供应态和球化退火态两种T12钢基体上渗钒初期的覆层形貌和成分分布。结果表明:在不同温度下渗钒,覆层的初期生长都是初始晶核不断形成并生长,直至覆盖整个表面,同时在初始晶粒上生成超细晶粒,最终形成非常光滑的表面;温度不同,则覆层形成类似形貌所需的处理时间不同;覆层形成初期的形貌受基体组织的影响,使基体中的渗碳体均匀分布有利于均匀致密覆层的形成。

Salt-bath vanadizing process was carried out at different temperatures on the T12 steel substrate for different time.By scanning electron microscopy,XRD,electron microprobe,vanadizing surface morphology evolution at the early stage was analyzed.And comparison of the morphology and composition distribution of initial vanadizing coating between the substrates of domestic supply state T12 steel and globalization annealed state T12 steel was performed.The following results can be obtained： 1） at different temperatures,all the initial vanadizing coatings are formed through initial nucleation and growth to cover the whole substrate,and sub-micro sized grain formation on the initial grains,and finally formation of a very smooth surface,2） the time for formation of similar morphology is different at various temperatures,3） the microstructure of substrate has effect on the early appearance of vanadizing coating and the uniform distribution of cementite in the substrate helps the formation of uniform and dense coating.