| 英文摘要 |
The purpose of this article is to investigate the effect of heat treatmenton Ni-Cr-Mo structural alloy steel JIS-SNCM 439. Charpy V-notch impactspecimens quenching treatment had carried out to find optimum quenchingconditions by conducting impact tests and hardness measurements. Theimpact specimens and tensile specimens were quenched using above theoptimum quenching conditions, then tempered for 2 hours double temperingat 200°C~600°C, and impact tests, tensile tests, hardness measurements,microstructures and SEM fracture surface morphology observations wereconducted to reveal the effect of quenching and tempering conditions onmechanical properties, microstructures and fracture surface morphology.The results show that the optimum quenching temperature is 875°Cand austenitizing time is 30 minutes for JIS-SNCM 439, and the temperingtemperature for the optimum combination of strength and toughness is about 250°C. The hardness and tensile strength will decrease withincreasing tempering temperature, the toughness increases initially withtempering temperature but declines sharply reaching a minimum intoughness at 300°C. The fracture of impact specimens has a cleavage (orquasi-cleavage) morphology while tempering temperature is at 200°C~300°C, the fracture has a ductile morphology which shows many dimpleswhile tempering temperature is above 500°C. The fracture surface oftensile specimens shows a milling cutter fracture when temperingtemperature is under 300°C, and a cup-and-cone fracture when temperingtemperature is above 400°C. |
本站僅提供期刊文獻檢索。
