Simulation on rolling process of vanadium-bearing spring steel 55SiCrV
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摘要: 以一种实验室冶炼的含钒弹簧钢55SiCrV为原材料,借助CCT曲线绘制、热模拟试验和金相组织观察等手段研究了55SiCrV轧制变形温度和冷却速度对其力学性能和金相组织的影响,分析确定了其合理的轧制及冷却工艺参数范围。结果表明:55SiCrV 的CCT曲线显示其马氏体生成临界冷速约3 ℃/s,马氏体生成温度Ms点约245 ℃;55SiCrV实际轧制过程中的轧制变形温度应控制低于900 ℃且冷却速度不高于5 ℃/s,这样可以避免显微组织中生成马氏体而显著恶化其疲劳性能的同时保证其获得最佳的强度和韧性匹配。Abstract: A new spring steel 55SiCrV smelted in the laboratory was used as the raw material i n this paper to investigate the effects of rolling deformation temperature and cooling speed on the mechanical properties and microstructure of 55SiCrV by means of CCT curve drawing, thermal simulation test and metallographic structure observation, and the reasonable parameters of rolling and cooling process were determined. The CCT curve of 55SiCrV shows that the critical cooling rate of martensite formation is about 3 ℃/s, and the temperature of martensite formation is about 245 ℃. The rolling deformation temperature of 55SiCrV should not be higher than 900 ℃ and the cooling rate should be lower than 5 ℃/s in the actual rolling process, which can avoid the formation of martensite in the microstructure and significantly deteriorate the fatigue performance, while ensuring the best combination of strength and toughness.
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Key words:
- spring steel /
- 55SiCrV /
- rolling /
- deformation temperature /
- cooling rate /
- martensite
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表 1 试样主要化学成分
Table 1. Main chemical conpositions of used samples
% C Si Mn P S Cr V 0.57 1.23 0.74 0.008 0.005 0.65 0.20 表 2 试验钢力学性能
Table 2. Mechanical Properties of test steel
Rp0.2/MPa Rm/MPa Z/% 616 1057 34.5 表 3 不同冷却速度的金相组织
Table 3. Microstructures of samples after cooling at different cooling rate
冷速/(℃·s−1) 金相组织 冷速/(℃·s−1) 金相组织 40 马氏体 2 珠光体+铁素体 20 马氏体 1 珠光体+铁素体 10 马氏体 0.5 珠光体+铁素体 5 马氏体+珠光体 0.2 珠光体+铁素体 表 4 控冷工艺对组织的影响
Table 4. Effect of controlled cooling process on structure
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