We apply the system to the ultra - fine grain steel welding , the simulated mean grain size in cghaz agreed well with the corresponding independent experimental data . in this paper , three factors influencing the grain growth , the steep temperature gradient in haz . the grain boundary liquid and the precipitates particle , were studied specially using mc technique 研究表明温度梯度造成的“热钉扎”现象和晶界液化现象都对靠近熔合线附近的晶粒长大有明显的阻碍作用，对最终的晶粒大小分布有重要的影响：而800mpa超细晶粒钥中的tin粒子山于溶解温度高，抑制奥氏体晶粒长大的效果十分显著。
The effects of some important factors on structure , pore size , porosity , flux , weight of vapor transfer , etc . have been investigated by changing temperature of pvdf resolution , types of solvent , molecular weight of pvdf , weight of additive , time of solvent pre - evaporation and so on . the optimal process of making membrane and recipe of solution were made out 然后通过改变pvdf溶解温度，铸膜液的溶剂， pvdf的分子量， pvdf用量，添加剂氯化锂用量，涂膜时预挥发时间，凝固浴温度以及凝固浴中无机盐氯化钠、溶剂丙酮等影响因素，考察这些因素对膜形态结构及孔径，孔隙率，水通量，透湿量等性能的影响规律，初步确定了铸膜液配方及涂膜工艺条件。
