| 低成本超高强度钢G31L的过冷奥氏体连续冷却转变 |
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| 引用本文： | 杨鹏,宁静,苏杰,姜庆伟. 低成本超高强度钢G31L的过冷奥氏体连续冷却转变[J]. 金属热处理, 2020, 45(12): 149-154. DOI: 10.13251/j.issn.0254-6051.2020.12.030 |
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| 作者姓名： | 杨鹏 宁静 苏杰 姜庆伟 |
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| 作者单位： | 1.昆明理工大学 材料科学与工程学院, 云南 昆明 650093;2.钢铁研究总院 特殊钢研究所, 北京 100081 |
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| 摘 要： | 利用Formast-FⅡ膨胀仪测定了G31L钢的热膨胀曲线,研究其在不同冷速下的组织演变及硬度变化规律,绘制出G31L钢过冷奥氏体连续冷却转变(CCT)曲线,并分析了实际大型深盲孔锻件的锻后热处理工艺可靠性。结果表明:G31L钢的Ac1=740 ℃、Ac3=816 ℃,Ms=315 ℃、Mf=138 ℃。当冷速≤0.028 ℃/s时,获得珠光体、铁素体、贝氏体混合组织;当冷速在0.028~0.84 ℃/s之间,随冷速增大,珠光体-铁素体消失,贝氏体量逐渐降低,直至转变为全马氏体组织;当冷速大于0.84 ℃/s时,获得全马氏体组织。实际生产的大型深盲孔锻件经915 ℃保温6 h后油淬至室温并进行回火处理,锻件实心头部的心部为马氏体和少量贝氏体的混合组织,头部R/2处、头部边部及尾部为全马氏体组织,且锻件的强度和塑性均满足产品质量要求。
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| 关 键 词： | CCT曲线 马氏体 超高强度钢 深盲孔锻件 |
| 收稿时间： | 2020-05-16 |
Continuous cooling transformation of super cooled austenite of a low-cost ultra-high-strength steel G31L |
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| Yang Peng,Ning Jing,Su Jie,Jiang Qingwei. Continuous cooling transformation of super cooled austenite of a low-cost ultra-high-strength steel G31L[J]. Heat Treatment of Metals, 2020, 45(12): 149-154. DOI: 10.13251/j.issn.0254-6051.2020.12.030 |
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| Authors: | Yang Peng Ning Jing Su Jie Jiang Qingwei |
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| Affiliation: | 1. Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming Yunnan 650093, China;2. Institute for Special Steels, Central Iron and Steel Research Institute, Beijing 100081, China |
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| Abstract: | Thermal dilatometric curves of G31L steel were measured by Formastor-FⅡdilatometer, and the microstructure evolution and hardness at different cooling rates were studied, the supercooled austenite continuous cooling transformation(CCT) curves of the G31L steel were drawn, and the reliability of post-forging heat treatment process of real large deep blind hole forging was analyzed. The results show that the critical temperatures of the G31L steel as follows:Ac1=740 ℃, Ac3=816 ℃, Ms=315 ℃, and Mf=138 ℃. When the cooling rate is less than or equal to 0.028 ℃/ s, pearlite+ferrite+bainite mixed structure is obtained; when the cooling rate is 0.028-0.84 ℃/s, pearlite and ferrite disappear with the increase of cooling rate, and bainite decreases in content gradually until full martensite is obtained; when the cooling rate is greater than 0.84 ℃/s, full martensite is obtained. The large deep blind hole forgings actually produced are heat treated at 915 ℃ for 6 h and then oil quenched to room temperature and tempered. The solid head core of the forgings has a mixed structure of martensite and a small amount of bainite, while the R/2 and edge of the head and tail are all martensite, and the strength and plasticity of the forgings meet the product quality requirements. |
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| Keywords: | CCT curves martensite ultra-high-strength steel deep blind hole forgings |
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