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采用粉末冶金的方法制备DT300低合金高强度钢,研究了烧结温度、粉末粒度对粉末冶金制备DT300钢的影响,并将其显微组织及性能与铸造制得的DT300钢进行对比分析。结果表明,真空气雾化制得的25μm的粉体经冷等静压机280 MPa保压1 200 s后,在真空烧结炉中进行烧结,烧结温度1 250℃,保温1 200 min,最终获得致密度达99.12%的DT300钢。经920℃×1 h油淬+300℃×2 h回火热处理后其抗拉强度达到1 850 MPa,冲击功95 J,硬度65 HRC。粉末冶金法和铸造法生产的DT300钢性能不相上下,但是粉末冶金可以大大减少后续机加工量,节约金属材料,提高劳动生产率。因此在薄壁和精密件的生产上可以用粉末冶金法替代铸造法。
The DT300 low-alloy high-strength steel was prepared by powder metallurgy. The effect of sintering temperature and powder particle size on the preparation of DT300 steel by powder metallurgy was studied. The microstructure and properties of DT300 steel were compared with the cast DT300 steel. The results showed that the 25μm powder obtained by vacuum gas atomization was pressed by cold isostatic press at 280 MPa for 1 200 s and then sintered in a vacuum sintering furnace at a temperature of 1 250 ℃ for 1 200 min and finally obtained DT300 steel with a density of 99.12%. The tensile strength reached 1 850 MPa, impact energy 95 J, hardness 65 HRC after the oil quenched at 920 ℃ for 1 h and the tempering heat treated at 300 ℃ for 2 h. Powder metallurgy and casting method of DT300 steel production comparable, but the powder metallurgy can greatly reduce the follow-up machining volume, saving metal materials, improve labor productivity. Therefore, thin-walled and precision parts can be used in the production of powder metallurgy instead of casting method.