摘要
采用固溶处理+分级淬火,研究了固溶处理后不同淬火温度下的D2的碳化物演变规律,获得了碳化物的溶解顺序,分析了碳化物溶解的热力学机理,实验表明:随着淬火温度的升高,D2钢中碳化物含量下降.在920 ℃淬火温度下,组织中含有大量球状碳化物,分布密集,尺寸不均匀,隐晶马氏体和残余奥氏体很少;当温度升高到1 000 ℃,球状碳化物粒径变细小,呈弥散分布;当淬火温度达到1 080℃,球状碳化物消失,出现针状马氏体.同时淬火温度的上升,合金元素在碳化物中溶解率升高,体积较小的共晶碳化物发生溶解,体积较大的共晶碳化物随后溶解,碳化物的溶解,奥氏体中碳元素和合金元素的含量升高,温度升高,合金元素的扩散速率也增加,合金元素在奥氏体分布均匀,奥氏体相的稳定性提高,降低马氏体转变温度.综上,在1 150 ℃固溶处理+1 080℃淬火时碳化物均匀细小,呈球化形态,可有效控制淬火裂纹,提高D2钢的强韧性.
Abstract
After solution treatment and fractional quenching,the carbide evolution of D2 under different quenching temperatures was studied,the dissolution order of carbide was obtained,and the thermodynamic mechanism of carbide dissolution was analyzed.The experiment showed that the carbide content in D2 steel decreased with the increase of quenching temperature.At the quenching temperature of 920℃,the micro-structure contains a large number of spheroidal carbides,the distribution is dense,the size is not uniform,and the cryptocrystalline martensite and residual austenite are few.When the temperature rises to 1 000 ℃,the particle size of the spherical carbide becomes smaller and becomes dispersed.When the quenching temperature reaches 1 080℃,the spherical carbides disappear and acicular martensite appears.At the same time,with the increase of quenching temperature,the dissolution rate of alloying elements in carbides increases,the smaller eutectic carbides dissolve most,the larger eutectic carbides then dissolve,the dissolution of carbides,the content of carbon and alloying elements in austenite increases,the temperature increases,the diffusion rate of alloying elements also increases,and the alloying elements are evenly distributed in austenite.The stability of the austenitic phase is improved and the martensitic transition temperature is reduced.In summary,the carbide is uniform and fine when quenched at 1 150 ℃+1 080℃,which can effectively control the quenching crack and improve the strength and toughness of D2 steel.
基金项目
国家级大学生创新创业训练计划(202213898010)
天津市一流本科课程建设项目(YLKC201902)
北京科技大学天津学院本科教育教学改革与研究重点项目(tyjy2021002)
维普
万方数据