改善30CrMnSiNi2A钢强韧性的热处理工艺研究

The Study of the Heat-treatment Process for Improving the Strength and Toughness of 30CrMnSiNi2A Steel

用正交试验法研究了等温温度、等温时间、奥氏体化温度和原始组织状态对30Cr-MnSiNi2A钢马氏体区等温淬火+回火后组织与性能的影响。提出了可保证该钢在上、中、下限含碳量的各项性能指标均达到技术要求的强韧化热处理工艺。试验结果表明,与现行工艺相比,新工艺可使σ_b提高70～80MPa,σ_(0.2)提高80～140MPa,低周疲劳寿命提高18%,特别是K_(IC)和K_(ISCC)有较大幅度的提高,而塑性和低温(-50℃)α_K值保持不变,室温α_K值略有降低,但仍远高于技术条件要求。文中对新工艺能显著改善钢的强韧性的原因作了分析。

The effects of isothermal temperature,isothermal holdingtime,austenitizing temperature and prior structure on the microstrure andmechanical properties of 30CrMnSiNi2A steel after austempering and tem-pering under Ms point were studied using orthogonal experimental method.A new heat-treatment process was suggested,which can ensure the steelwhich carbon contents are within upper and lower limit to meet the tech-nical requirement.The experiments prove that comparing with current pr-ocess,the suggested process makes σ_(?) and σ_(0.2)to increase 70～80Mpa and80～140Mpa respectively,and the fatigue strength(the low cycle fatigurelife)increases by 18%,especially the K_(IC)and K_(ISCC)being greatly increa-sed.However,the plasticity and the subzero(-50℃)a_K have no change,and the room temperature a_K decreases little but was still much higherthan the technical requirement.The reason for the suggested process enh-ancing the strength and toughness of this steel was discussed in thispaper.