摘要
对于尺寸较大的高碳合金钢轴(辊)类件而言,外圆表层在快速加热喷冷淬火时,一定深度的表层部分会因为相变而产生体积膨胀,从而使心部承受拉应力。加热温度越高、冷却越激烈,则淬硬层越深,心部拉应力就越大。但喷淬过程中心部温度尚处于较高状态,可以通过应变使这种应力得到协调或松弛,因而一般不会造成开裂。心部的这种开裂常常发生在热处理后的放置过程中,即所谓"置裂"。本文运用常规金相分析的方法,确定70Cr3Mo钢支承辊的断裂属于置裂并具体指出该支承辊发生置裂的主要原因是:最后热处理加热温度偏高,导致淬层马氏体粗大、残余奥氏体增多。
During flash heat spraying quenching for larger size high carbon steel shafts（ rolls）, a certain deep from excircle surface layer may come into being volumetric expansion by reason of phase change and accordingly the core endures tensile stress. The higher heating temperature, the more severity cooling, the deeper quench hardening layer and the larger the core tensile stress is. When the core＇s temperature still is higher, the stress may be matched or relaxed by strain so that not to bring about cranking. The cracking of the core frequently happens in put procedure after heat treatment, i.e. what is called put cracking. Determine that 70Cr3Mo steel back rollg rupture belongs to put cracking by using general metallurgical analysis method and the reason is that final heat treatment heating temperature is on the high side resulting in martensite grossness and residual austenite adding.
出处
《大型铸锻件》
2010年第2期18-21,共4页
Heavy Casting and Forging
