Abnormal Grain Growth in Sintered Ferritic Stainless Steel
Abnormal Grain Growth in Sintered Ferritic Stainless Steel
复制标题
烧结铁素体不锈钢中的异常晶粒生长
DOI：
10.2497/jjspm.36.824
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Y. Tokunaga
中科院分区：
文献类型：
--
作者：
M. Kamada;K. Hanata;Y. Tokunaga
高绿色密度的SUS 410 L粉末压坯在1250°C真空烧结过程中铁素体晶粒异常长大。烧结后，超粗晶尺寸可达几毫米。在铸造和锻造的SUS 410 L钢中，晶粒在高温下立即开始长大，而在烧结钢中，晶粒有一个异常长大的孕育期，为了解释这种异常晶粒长大的过程，根据Zener方程提出了一个表达式：fz=c（p/r ′-ε an）其中fz是孔隙对晶界迁移的限制力，p是孔隙率，r'是具有相同实际角孔体积的球体的半径，a是孔形状因子（a≤1），c和n是常数。随着烧结的进行，fz逐渐减小，这是因为致密化使p减小，孔的奥斯特瓦尔德熟化使r'增大，孔的球化使a接近1。因此，一些晶粒开始逆着fz生长，并导致形成超粗晶粒。
The ferritic grains of SUS410L powder compacts with high green density abnormally grew during vacuum sintering at 1250°C. After the sintering, the size of super coarse grains reached to a few millimeter. In the cast and wrought SUS410L steels, the grain growth started as soon as they were held at high temperature, but in sintered steels, there was the incubation period for grain growth.In order to explain the process of this abnormal grain growth, an expression based on Zener's equation was proposed.fz=c(p/r'⋅an)where fz is the restraining force for boundary migration by pore, p is the porosity, r' is the radius of the sphere which has the same volume of actual angular pore, a is the pore shape factor (a≤1) and c and n are the constants. As the sintering proceeds, the fz gradually decreases because the p decreases by densitication, r' increases by Ostwald ripening of pores and a approaches to 1 by spheroidization of pores. Therefore, some grains start to grow against the fz and result in forming the super coarse grains.