Effect of Nb and V on the microstructures and properties of X80 hot pipe steel
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摘要: 设计在X80热煨弯管用钢中添加不同含量的微合金元素Nb、V,并采用OM、SEM、TEM进行试样微观组织和析出相的观察,利用拉伸试验机和冲击试验机进行力学性能的测试,应用Thermo-calc软件进行试验钢热力学计算。结果表明:减少试验钢中的Nb或V含量后,试验钢的固溶强化分量降低;纳米析出相的体积分数增加,平均直径减小,试验钢的析出强化分量提高;细晶强化分量相差不大,最终试验钢的屈服强度和抗拉强度降低,而试验钢在−20 ℃的冲击功显著提高。研究证实,添加约0.02%Nb、0.04%V元素有助于改善X80热煨弯管用钢材料的强韧性匹配。
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关键词:
- 热煨弯管 /
- Nb、V复合微合金化 /
- 微观组织 /
- 力学性能 /
- 析出相
Abstract: In this study, different contents of micro-alloying elements Nb and V were added to X80 pipeline steel. OM, SEM and TEM were used to observe the microstructures and precipitates. Tensile tests and Charpy tests were conducted to obtain the mechanical properties. Thermo-calc software was used for phase transformation calculation. The results showed that after reducing the Nb or V contents in the tested steel, the ratio of solid solution strengthening of the steel decreased; the volume fractions of the nano precipitates increased; the average diameters of the nano precipitates decreased; the ratio of precipitation strengthening of the tested steel increased; and the ratio of grain refinement strengthening of the steel was not obvious. Finally the strength of the tested steel was reduced, while the impact energy at -20 ℃ was significantly increased. This research has confirmed that adding appropriate amounts of 0.02%Nb and 0.04%V elements can improve the strength and toughness matching of materials. -
表 1 试验钢化学成分
Table 1. Chemical compositions of three tested steels
% 试验钢 C Si Mn+Cr+Mo Ni+Cu Ti Nb V Al Fe 06Nb1V 0.07 0.25 2.2 0.3 0.03 0.06 0.1 0.03 Bal. 02Nb1V 0.07 0.25 2.2 0.3 0.03 0.02 0.1 0.03 Bal. 06Nb04V 0.07 0.25 2.2 0.3 0.03 0.06 0.04 0.03 Bal. 表 2 试验钢的生产工艺参数
Table 2. Production process parameters of the investigated steels
奥氏体化温度/℃ 奥氏体化时间/min 冷却方式 回火温度/℃ 回火时间/min 950 40 水冷 600 60 表 3 纳米析出相的统计结果
Table 3. Statistical results of the precipitated particles
试验钢 体积分数/% 析出相平均尺寸/nm 06Nb1V 0.30 31.86 02Nb1V 0.07 20.20 06Nb04V 0.54 23.87 表 4 试验钢的力学性能
Table 4. Mechanical properties of the investigated steels
试验钢 屈服强度/MPa 抗拉强度/MPa 断后延伸率/% 冲击功/J 06Nb1V 695 779 17.96 166 02Nb1V 643 712 20.60 206 06Nb04V 644 718 16.86 304 -
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