The concurrent use of micro-alloying additions and thermomechanical treatment is a common practice for obtaining high-quality grades of forged steels. Judicious use of chemistry, heat treatment schedule, and controlled processing can lead to a wide range of microstructure and thus final properties suitable for the production of different parts for the automobile industry. In this paper, thermomechanical treatment of Ni-added micro-alloyed steel containing Nb, V, Ti has been carried out with different deformation schedules (50-70%) at high temperatures followed by the varying cooling rate (i.e., forced air cooling, oil quenching, and water quenching). The cooling rates for three conditions were measured as 5 °C/s for forced air cooling, 40 °C/s for oil quenched, and 110 °C/s for water quenched samples. Thermomechanical and post-tempering treatment cycles were employed for the steel with 1150 and 900 °C as upper and lower forging temperatures. The best combination of properties viz; YS: 1044 MPa, UTS: 1308 MPa, % El: 16.7, %RA: 57 and Impact Toughness: 50 J/cm² could be achieved for 70% deformed samples, followed by forced air cooling. The reasons have been attributed to the segregation of Ti & Nb carbides at grain boundaries as revealed by microstructural analysis. This has led to restriction of grain boundary coarsening at high temperatures. Further, fine vanadium carbide and the presence of retained austenite have contributed to improving the elongation and toughness values.

同时使用微合金化添加物和热机械处理是获得高质量牌号的锻钢的常见做法。明智地使用化学物质，热处理程序和受控处理可导致广泛的微观结构，因此最终的性能适用于汽车行业的不同零件的生产。在本文中，已在高温下以不同的变形进度（50-70％）对含Nb，V，Ti的添加Ni的微合金钢进行了热机械处理，然后改变了冷却速率（即强制风冷，油淬火和水淬火）。三种条件下的冷却速率测量为：强制风冷为5°C / s，油淬火为40°C / s，水淬火样品为110°C / s。钢的热机械和回火处理周期分别采用1150和900°C作为上下锻造温度。属性的最佳组合，即：YS：1044 MPa，UTS：1308 MPa，％El：16.7，％RA：57和冲击韧性：50 J / cm对于70％变形的样品，可以实现²，然后进行强制空气冷却。如显微组织分析所揭示的，原因可归因于Ti和Nb碳化物在晶界的偏析。这导致了高温下晶界粗化的限制。此外，细的碳化钒和残余奥氏体的存在有助于改善伸长率和韧性值。