25CrMnB钢228节距履带的热处理工艺

Heat treatment process of 25CrMnB steel 228 pitch crawler belt

通过金相显微镜及力学性能测定,研究了不同热处理工艺对25CrMnB钢力学性能的影响。结果表明,25CrMnB钢随淬火温度提高,晶粒逐渐粗化;随回火温度提高,强度及硬度下降,250～350℃回火时,存在韧塑性恶化区,150～250℃回火时,韧性下降,塑性先升后降,在200℃达最大值。在(880±20)℃淬火+(220±10)℃回火后,履带板具有良好的综合性能,Rm≥1500 MPa、A≥10%,KU2(常温)≥70 J,表面硬度40.0～45.0 HRC,满足了技术条件的要求。

Effect of heat treatment on 25CrMnB steel was studied by metallurgical microscope and mechanical properties test. The results show that grain size of the steel increases gradually with quenching temperature increasing. Strength and hardness decreases with tempering temperature increasing, there is a toughness deterioration region in the range of 250-350 ℃. Toughness decreases and ductility increases first and then decreases in the range of 150-250 ℃ , and reaches the maximum value at 200 ℃. The 25CrMnB 228 pitch crawler belt has good comprehensive mechanical properties after quenched at 880 ± 20 ℃ and tempered at 220 ± 10 ℃, Rm ≥ 1500 MPa, A ≥ 10% ,KU2 （ ambient temperature）≥70 J, surface hardness is between 40.0-45.0 HRC which meets the technical requirements.