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采用复合电冶熔铸工艺制备了以5CrNiMo钢为基体、WC颗粒为增强相的颗粒增强钢基复合材料,通过宏微观硬度试验、三点弯曲试验和冲击韧性试验对比分析并综合评定复合材料和5CrNiMo钢的各项力学性能,同时采用扫描电子显微镜观察断口形貌并判定断裂机理。结果表明:大量WC颗粒增强体分布在较软的钢基体上,提高了复合材料的整体硬度,淬透性和淬硬性也较好,但塑性比5CrNiMo钢稍差。在950℃到1050℃淬火时,复合材料的洛氏硬度达到60~66 HRC,抗弯强度达到1600~1650 MPa,均呈现先上升后下降的波动趋势,而冲击韧度变化不明显。对比基体和中小块WC颗粒聚集区,大块硬质相的显微硬度值变化幅度较小。在锻造退火状态下,复合材料为准解理+韧窝的复合断裂机理,而在淬火回火态时,则转变为解理断裂机制。
A composite steel based 5CrNiMo steel with WC particles as reinforcing phase was prepared by composite electroforming process. The microstructure and properties of composite materials and 5CrNiMo were evaluated by macro-micro-hardness test, three-point bending test and impact toughness test. The mechanical properties of steel, while using scanning electron microscopy fracture morphology and determine the fracture mechanism. The results show that a large amount of WC particles are distributed on the softer steel matrix, which improves the overall hardness, hardenability and hardenability of the composites, but the plasticity is slightly worse than that of 5CrNiMo steel. When quenched from 950 ℃ to 1050 ℃, the Rockwell hardness of the composites reaches 60 ~ 66 HRC and the flexural strength reaches 1600 ~ 1650 MPa, which shows the trend of first rising and then decreasing. However, the impact toughness does not change obviously. Compared with the matrix and small particles of WC particles agglomeration area, the microhardness value of large hard phase changes less. In the as-cast annealed condition, the composite material is the mechanism of the composite fracture of the quasi-cleavage + dimple, whereas it changes to the mechanism of cleavage and fracture in quenching and tempering.