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通过OM、SEM与TEM分析新型奥氏体热作模具钢6Mn14Cr3Mo2V2的微观组织,利用电解法萃取6Mn14Cr3Mo2V2在退火、固溶及时效状态下的碳化物,通过XRD对其进行物相分析,并与Thermo-Calc热力学相图计算结果进行比较。研究表明:钢中组织为单相奥氏体+碳化物,在时效状态下,钢中碳化物含量约为4.59%,碳化物类型为VC,与Thermo-Calc计算结果基本符合。根据上述结果提出6Mn14Cr3Mo2V2强韧化机制:时效态下,铬与钼元素不形成碳化物,固溶在奥氏体中起固溶强化作用;钢中主要强化相为时效过程中弥散析出的粒径10 nm左右的VC,而固溶过程中未溶的较大体积的VC钉扎在奥氏体基体上,阻碍晶粒长大,起细化晶粒作用。
The microstructures of the 6Mn14Cr3Mo2V2 austenitic hot work die steel were analyzed by OM, SEM and TEM. The carbides of 6Mn14Cr3Mo2V2 in the annealed, solution and aged state were extracted by electrolysis, and their phases were analyzed by XRD. -Calc thermodynamic phase diagram calculation results are compared. The results show that the microstructure of the steel is single phase austenite + carbide. Under aging condition, the content of carbides in steel is about 4.59% and the type of carbide is VC, which is in good agreement with Thermo-Calc calculation. According to the above results, we proposed the strengthening and toughening mechanism of 6Mn14Cr3Mo2V2: under aging condition, chromium and molybdenum do not form carbides and solid solution dissolves in austenite; the main strengthening phase in steel is the dispersed precipitated particle size About 10 nm VC, while the solution of insoluble large volume of VC pinned in the austenite matrix, hinder the grain growth, play the role of grain refinement.