合金钢的退火不软化行为

来源期刊：中南大学学报(自然科学版)2001年第3期

论文作者：刘佐仁

文章页码：298 - 301

关键词：合金钢;退火软化;等温退火

Key words：alloy steel; annealing soften; isothermal annealing

摘    要：某些合金经热处理后产生退火不软化问题.作者对W₁₈Cr₄V和18Cr₂Ni₄WA 2种合金钢进行了锻后软化退火试验,对退火组织进行了SEM分析,对合金钢的退火不软化原因进行了探讨,提出钢的退火必须根据等温转变C曲线(即TTT图),以确定其方法与工艺,从而获得最佳的切削加工性能.实验结果表明: W₁₈Cr₄V钢经普通退火处理,硬度偏高(269~286 HBS);采用等温退火方法,软化效果好,满足了切削加工对硬度的一般要求(<255 HBS);无论采用何种退火方法,18 Cr₂Ni₄WA合金钢的硬度均不能满足要求,只有采用高温回火的办法,方可使其软化.

Abstract: The soften annealing experiment of two kinds of alloy steels W₁₈Cr₄V and 18Cr₂Ni₄WA has been carried out In combination with the analysis of SEM micrographs, the mechanismof anti-annealing softening behaviour of these steels was discussed. It is pointed out that, in order to get a good machinability, it is necessary determine the heat treatment procedure carefully according to the isothermal phase transformation curves (i.e. TTTfigure) of these steels. The results showed that the hardness of W₁₈Cr₄V after common annealing was a bittoo high, and the soften effect was much better by isothermal annealing, the annealed hardness (<255 HBS) was satisfying for cut machining, while for 18Cr₂Ni₄WA, no matter how it is annealed, itwas difficult to soften. The hot forged 18Cr₂Ni₄WA can be fully softened only by high temperature tempering. An observation on annealed microstructure by SEM was conducted. Itwas found there was some difference on the particle size of carbide in the HSS (W₁₈Cr₄V) microstructure after austenizing at800℃and then, is other mal annealing at 720 and 750℃respectively. When the decomposition of overcooled austenite takes place at higher temperature, the lower the temperature of isothermal annealing, the more fine dispersed carbide particles were yielded. This microstructure difference evidently affects the annealed hardness.