To reheat hardened steel or hardened cast iron to some temperature below the eutectoid temperature for the purpose of decreasing hardness and increasing toughness.
重新加热硬化钢或硬化铸铁至某一温度，低于共析温度下，使硬度降低，韧度增加。
2
A simplified diagram, such as the one in Fig. 2.1, focuses on the eutectoid region and is quite useful in understanding the properties and processing of steel.
如图2.1所示的简化铁碳状态图将焦点集中在共析区，这对理解钢的性能和处理是十分有用的。
3
Both steel iron and cast iron have the structures of eutectoid, hypoeutectoid and hypereutectoid.