中碳钢球化退火行为和力学性能的研究

Behavior in Spheroidizing Annealing and Mechanical Properties of Medium Carbon Steel

采用常规双相区球化退火和亚温球化退火工艺研究了常规轧制(CR)和控轧控冷(CRC)的中碳钢SWRCH35K的球化退火行为和力学性能。结果表明,与传统的双相区球化退火相比,亚温球化退火时碳化物球化进程明显加快,球化率高,且碳化物比较细小,具有良好的塑性和冷成形性,采用亚温球化退火处理可明显地缩短球化退火时间。控轧控冷的中碳钢线材尽管具有比较粗大的珠光体组织,但因有相当部分的珠光体发生退化,其球化退火进程要明显快于细珠光体组织。

The behavior in spheroidizing annealing and mechanical properties of controlled rolled and cooled （CRC） and conventional rolled（CR） medium carbon steel SWRCH35K were studied with two annealing cycles. One was the conventional intercritical annealing. The other was subcritical annealing, which involves heating to below A1 for several times. It was found that compared to intercritical annealing, spheroidization occurs more rapidly in subcritical process, with formation of finer and degenerated pearlite with many kinks and breaks. The higher spheroidization level and finer carbides make the steel having better ductility and cold formability. The rapid spheroidization in subcritical process greatly reduce the energy, time and cost of spheroidization. However, rapid spheroidization can not be observed in intercritical process as the original fine pearlite is dissolved at the temperature above A1. The spheroidization of controlled rolled and cooled wire rod, in which there are a lot of degenerated pearlite, occurs more rapidly than that of conventional rolled wire rod, although in which fine pearlite is observed too.