以超高强度钢 22SiMn2TiB 为对象,研究了在淬火、回火和配分状态下组织的演变规律.采用光学金相显微镜(OM)、扫描电镜(SEM)和 X 射线衍射技术(XRD)研究了不同处理状态下组织的演变规律.实验表明,回火或配分温度低于 320 ℃,板条马氏体组织形貌没有明显变化,且不随回火和配分时间的变化而变化;在此温度以上进行配分,不论配分时间的长短,组织皆转变为回火组织.表明 320 ℃为该钢材的临界回火、配分温度.随着回火温度的升高,位错密度下降;且 320 ℃以下温度回火或配分,马氏体衍射峰的半峰宽 FWHM 只是略有减少,表明虽然板条马氏体的组织形貌没有明显变化,但板条内的位错密度和内应力降低.
An ultra high strength steel,22SiMn2TiB,was used for the study of the effects of quenching,tempering and partitioning process on the evolution of microstructure.Optical microscope (OM),scanning electron micro-scope (SEM)and X-ray diffraction (XRD)were utilized for studying evolutions of microstructures after different treatments.The results show that there is not obvious change on the microstructure of the as-quenched lath mar-tensite when tempering temperature or partitioning temperature is below 320 ℃ whether the tempering time or par-titioning time is elongated.When partitioning temperature is higher than 320 ℃,the microstructure changes to tempered structure whether partitioning time is long or short.It is considered that 320 ℃ is a threshold value of tempering temperature or partitioning temperature for the steel.The density of dislocation would decrease with in-crease of tempering temperature or partitioning temperature.When tempering temperature or partitioning temper-ature is below 320 ℃,full width at half maxima slightly decreases which indicates that although there is not obvi-ous change on the morphology of lath martensite,the inner stress and density of dislocation in lath decrease.
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