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研究了回火温度对超高强钢微观组织及力学性能的影响,并借助扫描电镜、透射电镜分析了马氏体基体中铁的碳化物特征、微合金碳氮化物析出,马氏体板条内的位错形态以及冲击试样断口特征。结果表明:回火温度在150～600℃时,随着回火温度的升高,铁的碳化物从板条内析出过渡到板条间析出、晶界析出,并逐步粗化、近球化,细小微合金碳氮化物的析出量变化不明显,马氏体板条内的位错趋于平直化,位错密度不断下降。随着回火温度的升高,超高强钢的屈服强度先增大而后减小,抗拉强度单调降低,伸长率和-40℃冲击吸收能量的变化趋势相同,并在回火温度300℃时出现最小值。随着回火温度的变化,-40℃冲击试样的不稳定断裂区呈现出韧性断裂、准解理断裂以及混合断裂多种类型。
Abstract：Effect of tempering temperature on microstructure and mechanical properties of ultra-high strength steel was studied. The characteristics of iron carbides and microalloy carbonitrides precipitation in the martensite matrix, dislocation configuration in martensite lath and fracture characteristics of impact specimens were analyzed by scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results show that when the tempering temperature is 150-600 ℃, with the increase of tempering temperature, the iron carbide precipitates from intra-lath to inter-lath and grain boundary, and gradually coarsens and nearly spheroidizes. The precipitation amount of fine microalloyed carbonitride does not change obviously. The dislocation in martensite lath tends to be flattened and the dislocation density decreases. With the increase of tempering temperature, the yield strength of the ultra-high strength steel first increases and then decreases, the tensile strength decreases monotonically, and the change trend of the elongation and impact absorption energy at-40 ℃ is the same, and the minimum value appears at the tempering temperature of 300 ℃. With the change of tempering temperature, the unstable fracture zone of-40 ℃ impact specimen exhibits ductile fracture, quasi cleavage fracture and mixed fracture.
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基本信息:
DOI：10.13289/j.issn.1009-6264.2020-0175
中图分类号:TG142.1;TG156.5
引用信息:
[1]郑东升,刘丹,罗登等.回火温度对超高强钢微观组织及力学性能的影响[J],2020,41(12):90-96.DOI:10.13289/j.issn.1009-6264.2020-0175.
基金信息:
湖南省教育厅科学研究项目(19C0574);; 湖南省科技创新计划项目(2018XK2301)