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本文研究了 GCr15轴承钢经碳化物固溶微细球化预处理及固溶贝氏体预处理后,淬火、回火及等温淬火状态下,碳化物细化及马氏体混合组织对断裂韧性及强度的影响。试验结果表明,经固溶贝氏体处理及固溶微细球化预处理并淬火、回火后,可得到碳化物平均颗粒尺寸≦0.5μm的细小碳化物组织,与一般球化退火并淬火、回火组织相比,在相同的淬火温度下具有较高的强度与硬度,但其断裂韧性仍保持不变(或略有所提高);固溶微细球化处理后经一定时间保温的等温淬火,得到马氏体加贝氏体条状基体中分布着细小碳化物的微细混合组织,其断裂韧性及强度均显著提高。具有最佳配合的强韧性,且其第Ⅱ类显微内应力明显减小。扫描电镜观察分析表明,淬火、回火组织的断裂韧性试样,是以晶界断裂为主具有少量韧窝的混合型断口;经等温淬火得到马氏体与贝氏体组织,其断口为穿晶准解理断裂,且具有较高的撕裂棱。
In this paper, after GCr15 bearing steel pretreated by carbide solid solution micro-spheroidization and pre-treatment with bainite solution, under the condition of quenching, tempering and isothermal quenching, the effect of carbide refinement and martensite mixed structure on fracture toughness and The impact of strength. The results show that the microstructure of carbides with the average particle size ≦ 0.5μm can be obtained by the pretreatment of solution-treated bainite and solution-spheroidization and quenching and tempering, Tempering microstructure, compared with the same quenching temperature has high strength and hardness, but its fracture toughness remains unchanged (or slightly improved); solid solution microsphere treatment after a certain period of time isothermal quenching , The martensite plus bainitic strip matrix distribution of fine carbide mixed microstructure, the fracture toughness and strength were significantly improved. With the best fit of the toughness, and its Class Ⅱ micro-internal stress significantly reduced. Scanning electron microscopy analysis showed that the fracture toughness specimens of quenched and tempered microstructures are mixed fractures mainly composed of grain boundaries with a small number of dimples. The martensite and bainite structures are obtained by isothermal quenching, and the fracture is worn Crystal quasi-cleavage fracture, and has a high tearing edge.