The lift type critical region normalizing (LTCRN) heat treatment process (HTP) was put forward based on the fact the center part of heavy cylinder was prone to mixed grain and crystal grain structure, long period of heat treatment, large energy consumption after the isotherm type austenite region normalizing (ITARN) process. The microstructure and mechanical properties were verified by the proposed HTP method. The results show that the LTCRN on eliminating mixed grain is better than that with ITARN method, and the average grain size is 31 μm after the heat treatment. Also, part of cementite precipitation on the grain boundary plays a pining and strengthening role of the grain boundary and the cementite spheroidization and homogenization inside the grain is also more effective. Besides, the yield strength, tensile strength and the-30℃ charpy impact energy of the heavy cylinder material are 655 MPa, 729 MPa and 162 J respectively after the LTCRN HTP, with significantly more plastic ridge and the comprehensive mechanical properties are the same as the ITARN method. Compared with the ITARN, the holding time of LTCRN can be shortened by 30% and the normalizing temperature is also decreased, which greatly reduces the energy consumption.%针对加氢反应器大型筒节经轧制成型后心部易出现混晶和粗晶组织和当前等温式正火工艺热处理周期长、能源消耗大两大问题,提出升梯式正火热处理方案,并与传统的等温式正火热处理制度下组织和力学性能进行对比.研究结果表明:升梯式临界区高温侧正火对降低混晶度的效果优于等温式正火的效果,其热处理后平均晶粒粒径为31μm;升梯式临界区高温侧正火热处理后在晶界处析出部分渗碳体,对晶界起到钉扎强化作用,晶粒内部渗碳体球化和均匀化效果好;经升梯式正火热处理后材料的屈服强度、抗拉强度和-30℃夏比冲击吸收功分别为655 MPa,729 MPa和162 J,其低温冲击断口塑性脊数量明显,综合力学性能与等温式正火的相当;与等温式正火工艺相比,升梯式临界区高温侧正火热处理工艺可将正火保温时间缩短30%,正火加热温度降低,大大降低了能源消耗.
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