摘要
国标中氧化法与直接淬硬法是测定碳含量在0. 25%～1. 00%钢中晶粒度的主要方法,然而运用这两种方法得出的晶粒尺寸往往出现偏小的情况。本文通过对55SiCr弹簧钢分别运用直接腐蚀法、EBSD法、氧化法与直接淬硬法测定晶粒度,经过比较与分析得出:氧化法与直接淬硬法测得的晶粒尺寸相比较直接腐蚀法与EBSD法要小,其原因在于热处理后的试样中含有残留奥氏体小晶粒,在用软件评级时,误将一个大的晶粒因为残留奥氏体晶界的拐入而分割成两个小晶粒来统计,从而造成晶粒尺寸的偏小。人工去掉小晶粒或假设未考虑残留奥氏体时截点数为n,考虑残留奥氏体的影响,其截点数约为n+Dn,测量线段长度为L,校正前后的晶粒度分别为Z_1和Z_2,则有Z_1=L/n,Z_2=L/(n+Dn),进一步可以得出Z_2=Z_1/(1+D)。经这两种方法校正后得到的结果与直接腐蚀法和EBSD法获得的结果较为接近。
The oxidation method and direct quenching method in the national standard are the main methods for determining the grain size of steel with a carbon content of 0. 25%-1. 00%. However,the grain size results determined by these two methods are smaller than they actually are. In this paper,the grain size of 55 SiCr spring steel was measured by direct corrosion method,EBSD method,oxidation method and direct hardening method,respectively. After comparison and analysis,it is found that the grain sizes measured by oxidation method and direct hardening method are smaller. The reason is that the specimens after heat treatment contain small retained austenite grains. When calculating with a software,a large grain will be miss-divided into two small grains due to the turning-in of retained austenite grain boundaries,resulting in a small grain size. After artificially removing small grains,or without considering the retained austenite,the number of intercept points can be assumed n. Considering the influence of retained austenite,the number of intercept points is about n + Dn,the length of the measuring line is L,and the grain sizes before and after the correction are Z1 and Z2 respectively. Then there is Z1= L/n,Z2=L/( n + Dn). Further Z2= Z1/( 1 + D) can be drawn. The results after correction are similar to those of direct corrosion method and EBSD.
作者
陈杰
李文军
刘新宽
王军艺
盛荣生
Chen Jie;Li Wenjun;Liu Xinkuan;Wang Junyi;Sheng Rongsheng(School of Materials Science and Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Shandong Daye Co.,Ltd.,Zhucheng Shandong 262200,China;Baosteel Research Institute,Shanghai 201900,China;Sunnywell (China)New Material Technology Co.,Ltd.,Changzhou Jiangsu 213200,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2019年第1期219-222,共4页
Heat Treatment of Metals
关键词
氧化法
直接淬硬法
晶粒度
残留奥氏体
oxidation method
direct quenching method
grain size
retained austenite
