双层辉光离子渗W-Mo后析出物TTT图测定

Determination of TTT diagram of precipitates in diffusing layer after double glow plasma surface alloying with tungsten-molybdenum

双层辉光离子渗W Mo后由于冷却速度缓慢 ,渗层中尤其在晶界上出现大量析出物 ,造成渗层质量严重下降 ,虽后经固溶处理 ,但由于其组织遗传等原因 ,依然造成不良影响。针对这个问题 ,首先采用恒电流电解萃取析出物 ,然后用X射线衍射法对析出物进行定性分析 ,结果表明析出物主要为 μ相 ;其次应用金相法和定量金相分析仪测定了析出相的等温转变动力学图 ,该图表明析出相分别在 950℃和 1 1 50℃达到转变高峰 ,孕育期分别为 6～ 8min和 4～ 5min。

Because of the slow cooling speed after 20 steel alloyed by W Mo plasma, a lot of precipitation is produced in the W Mo alloying layers, especially at the grain boundaries. In spite of the solution heat treatment, the layer quality is negatively influenced due to microstructure inheritance. In order to get rid of or restrain the formation of the precipitated phases, the following work has been done: qualitative phase analysis of the precipitates by X ray diffraction, examination of their isotherms by means of quantitative metallographic analyzer and analysis of SEM images of the precipitation. [