古代钢铁制品中的浮凸组织初步研究

Investigation of ghosting structure in the iron and steel artifacts

为研究钢铁制品中浮凸组织产生的原因,对14件取自不同地方、属于不同时期的具有浮凸组织的样品利用金相组织鉴定、扫描电镜能谱分析、化学分析和显微硬度测定等方法进行了研究。结果表明:金相组织观察发现浮凸组织与夹杂物和铁素体晶粒间界有一定的关系,并存在有不同的形貌,其显微硬度均比附近基体高;成分分析表明有浮凸组织的样品磷含量要比没有浮凸组织的样品磷含量高一个数量级。有浮凸组织样品内部磷含量的分布也不均匀。这些结果说明,浮凸组织的产生主要原因是矿石中的磷在冶炼过程中进入铁中,而在随后的脱碳退火、炒炼和冷、热加工过程中均不能有效地脱去;同时,固溶在铁中的磷与铁形成薄膜阻止晶粒间界长大、或者在埋葬条件下长期时效引起的晶界移动而产生了浮凸组织。

Among all the ancient Chinese iron and steel artifacts that have been examined, more than 40 samples have ghosting structure, which is a significant phenomenum worth to study deeply for that it is seldom appeared in modern material. In order to research the reason that caused this kind of microstructure, 14 samples were selected and investigated by using metallographic, micro - hardness test, SEM - EDS and chemical analysis. These artifacts were excavated from Beijing, Liaoning, Shanxi, Shandong and Sichuan provinces. The dates of the making of these artifacts were varied from 8th century BC to 14th century AD. The metallographic analyses show that these artifacts were made by bloomery iron, puddling steel and decarburized steel and there were three kinds of microstructures:feather, block, reticular and crystal shaped ghosting structure. The chemical analyses indicate that the phosphorus content of samples with ghosting structures were 10 times higher than those samples without ghosting structure, and phosphorus content of areas having ghosting structure were 2-3 times higher than the areas without ghosting structure for the same sample. The micro - hardness test shows the similar condition: the micro - hardness of ghosting structure is higher than that of neighborhoods without ghosting structure. All the facts show that the structures were caused by phosphorus segregation during the smelting and forging process. Due to the chemical characters of phosphorus, it is very difficult to be reduced in the process of iron smelting and forging in the ancient times. In case of high phosphorus content ores, fuels or other materials were used to produce iron and steel, phosphorus segregated in the boundary of austenite grain, and in the succedent processes the high phosphorus areas were kept still, the ghosting structures were then appeared.