Ni对高碳工具钢75Cr1组织和性能的影响

为开发高性能、长寿命的木工圆锯片、带锯条、弹簧等五金工具，在75Cr1钢中分别添加质量分数为0.2%、0.4%的Ni元素。通过力学性能检验、显微组织分析以及热处理试验，研究了不同Ni含量对75Cr1钢热轧态及热处理态力学性能与显微组织的影响。结果表明，在Ni添加量为0%～0.4%的范围内，能降低热轧75Cr1钢的强度与硬度，提高塑性，其含量越高，效果越显著，但对冲击性能影响不明显；Ni对淬火硬度影响不大，当Ni含量达到0.4%时，硬度呈降低趋势，但明显提高回火后的塑性，降低回火后的强度与硬度，并改善回火后的冲击吸收能量，Ni含量越高，改善效果越明显。显微组织方面，Ni可以细化热轧75Cr1钢珠光体球团尺寸及片层间距，促进珠光体片的球化，同时也细化淬火与回火后的显微组织。结合经济性与综合力学性能考虑，75Cr1钢中Ni的最佳添加量为0.2%。

Effect of Ni on microstructure and properties of 75Cr1 high carbon tool steel

In order to develop woodworking circular saw blade, band saw, spring and other hardware tools with high properties and long life, the Ni element with mass fraction of 0.2% and 0.4% was added to the 75Cr1 steel, respectively. The effect of different Ni content on mechanical properties and microstructure of the 75Cr1 steel as hot rolled and heat treated was studied by mechanical property test, microstructure analysis and heat treatment test. The results show that within the range of 0%-0.4% Ni addition, the strength and hardness of the hot rolled 75Cr1 steel can be reduced, but the plasticity improved, the higher its content is, the more significant the effect is, however, the impact property is not obvious change. Ni content has little effect on quenching hardness, when it reaches 0.4%, the hardness of the steel shows a trend of decreasing, but the plasticity after tempering is obviously improved; after tempering, the strength and hardness of the steel are reduced, but the impact absorbed energy is improved. The higher the Ni content, the more obvious the improvement effect. On the aspect of microstructure, Ni can refine the size and lamellar spacing of the hot rolled 75Cr1 steel pearlite colonies, promote the spheroidization of lamellar pearlite, and refine the microstructure after quenching and tempering. Considering economy and mechanical properties, the optimal addition of Ni in the 75Cr1 steel is 0.2%.