大型筒节台阶式临界区正火热处理工艺  

Step type critical region normalizing heat treatment process of heavy cylinder

作　　者：孙建亮[1] 张永振[1] 彭艳[1] 戚向东[1] 郝露菡 

机构地区：[1]燕山大学国家冷轧板带装备及工艺工程技术研究中心,河北秦皇岛066004

出　　处：《钢铁》2015年第8期65-70,76,共7页Iron and Steel

基　　金：国家自然科学基金资助项目(51305388);河北省高等学校青年拔尖人才计划资助项目(BJ2014055)

摘　　要：针对加氢反应器大型筒节经轧制成形后心部易出现混晶、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,从热处理工艺入手,提出了台阶式临界区正火热处理方案,通过与传统的等温式正火热处理制度下组织和力学性能的对比,得出2次台阶式临界区高温侧正火为最佳的热处理工艺。研究结果表明:2次台阶式临界区高温侧正火消除混晶和细化晶粒的效果优于等温式正火,其热处理后平均晶粒尺寸为18μm,混晶组织基本消除,回火后渗碳体球化和均匀化效果好;2次台阶式临界区高温侧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681 MPa、768 MPa和181 J,综合力学性能优于等温式正火;-30℃冲击断口均为准解理断裂,其低温冲击断口塑性脊数量明显多于等温式正火热处理,低温冲击吸收功较大;与等温式正火工艺相比,2次台阶式临界区高温侧正火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。The step type critical region normalizing（ STCRN） heat treatment process（ HTP） was put forward as 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 after the proposed HTP methods were verified,and the two times STCRN was the best HTP. The results show that： First,the two-time STCRN on eliminating mixed grain and crystal grain is better than that with ITARN method,and the average grain size is 18 um after the heat treatment. Also,the cementite spheroidization and homogenization inside the grain is more effective. Besides,the yield strength,tensile strength and the- 30 ℃ charpy impact energy of the heavy cylinder material are 681 MPa,768 MPa and 181 J,respectively after two-time STCRN HTP,and the comprehensive mechanical properties are better than that with the ITARN method. Furthermore,the- 30 ℃ impact fracture after the twotime STCRN is quasi-cleavage fracture,with significantly more plastic ridge and larger low temperature impact absorbing energy than that with ITARN. Finally,compared with the ITARN,the holding time of two-time STCRN can be shortened by 30% and the normalizing temperature is also decreased,which greatly reduces the energy consumption.

关 键 词：大型筒节 台阶式临界区正火 热处理工艺 力学性能 

分 类 号：TG156.4[金属学及工艺—热处理]