铌合金钢的控制冷却工艺研究

Controlled Cooling Process for Bearing Steel with Nb Element

通过控制冷却速度的方法,研究了两组体育器械用Nb微合金化C-Si-Mn-Cr-Nb钢不同冷却速度下的显微组织和显微硬度的变化规律。结果表明,随着冷却速度的降低,两组钢的铁素体晶粒尺寸都逐渐减小,铁素体的体积分数都逐渐降低,在同样的冷却速度下,有Nb钢的铁素体晶粒尺寸更小、铁素体体积分数更低。Nb微合金化,对钢起到了晶粒细化和析出强化的作用,可以提高铁素体的硬度,但对贝氏体显微硬度的影响相对较小。

The effects of different controlled cooling rates on the microstructure and micro-hardness of two kinds of Nb microalloyed C-Si-Mn-Cr-Nb steel were studied. The results show that, with the decrease of cooling rate, the ferrite grain size and the volume fraction of ferrite are gradually reduced in the two kinds of steels. Under the same cooling rate, the ferrite grain size of Nb-alloyed steel is smaller, the ferrite volume fraction is lower. Nb microalloying plays a role of grain refining and precipitation strengthening on the steels, which can effectively improve the hardness of ferrite, but the effect on bainite hardness is relatively small.