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使热轧钢获得球化组织的最简单而又常用的方法是亚温退火。过共析钢热处理一般采用退火,即加热至Ac_1以上的温度而后慢冷或在亚临界温度作等温停留。实现此种退火的必要条件须在奥氏体化后的钢组织中保留未溶碳化物。按Fe—C状态图,对于过共析钢存在有奥氏体与碳化物处于平衡状态的温度区,这就决定了过共析钢具有很宽的退火温度范围,即从该温度范围冷却时,将形成球状碳化物。共析钢、尤其亚共析钢,没有此种温度区,因此退火范
The simplest and most commonly used method for obtaining hot-rolled steel into nodular structures is sub-temperature annealing. The hypereutectoid steel heat treatment is generally annealed, that is, heated to a temperature above Ac_1 and then slowly cooled or isothermally maintained at a subcritical temperature. The necessary conditions for achieving this kind of annealing must remain undissolved carbides in the austenitized steel structure. According to the Fe-C state diagram, there exists a temperature zone where austenite and carbides are in equilibrium with the hypereutectoid steel, which determines that the hypereutectoid steel has a wide annealing temperature range, ie, when cooling from this temperature range , A spherical carbide will be formed. Eutectoid steel, especially the sub-eutectoid steel, there is no such temperature zone, so Annealing Fan