【摘要】 利用C形缺口试样,研究Nb-B微合金化齿轮钢的渗碳热处理畸变。结果表明,由于细小的Nb(C,N)析出相在奥氏体晶界起钉扎作用,Nb-B微合金化渗碳齿轮钢的原奥氏体晶粒平均尺寸明显细于20CrMoH钢和22CrMoH钢。微量B使20CrMoH钢和22CrMoH钢的淬透性提高,理想淬透直径DI值增大,渗碳淬火畸变率增加;Nb微合金化细化晶粒,细晶粒齿轮钢的渗碳淬火畸变相对较小;Nb-B微合金化可实现淬透性提高而渗碳淬火畸变不显著增加。更多还原

【Abstract】 Heat treatment distortion of Nb-B microalloyed case hardening steels was investigated by means of Navy-C ring specimens.Results show that the case hardening steels microalloyed with Nb and B have fine prior austenite grain sizes in the carburized case as a result of the pinning effect of fine Nb(C,N)particles on austenite grain during carburization.Heat treatment distortion of 22CrMoH and 20CrMoH steels is increased by the addition of boron,which can remarkably improve hardenability and ideal diameter(DI value)of hardening;however it is decreased by the addition of niobium,which can evidently refine the prior austenite grain sizes.As a result,Nb-B microalloying can increase hardenability while it does not cause significant increase in quench distortion.更多还原