Effect of cooling system and forming structure on grain sizes and mechanical properties of S43CMnV for non‐quenched and tempered steel crankshaft

Abstract

AbstractTaking the given S43CMnV non‐quenched and tempered steel multi‐cylinder (3‐cylinder and 4‐cylinder) crankshaft as the research object, the intrinsic relationship between the forging process, temperature controlled cooling process of 3‐cylinder crankshaft and the global‐local grain evolution process was analyzed by Deform‐3D software. Meanwhile, the influence relationship between average grain sizes and comprehensive mechanical properties of the 3‐cylinder and 4‐cylinder crankshaft was compared and analyzed in details. The results show that for the 3‐cylinder crankshaft, the larger cooling rates can achieve the smaller grain sizes. When the temperature controlled cooling rate is 60 °C/min, the average grain sizes of the crankshaft pin bearing, main bearing and flange end are 61.5 μm, 96.9 μm and 70.7 μm respectively, which meets the requirements of production process (approximately 127 μm). Wherein, the grain sizes and mechanical properties of the 4‐cylinder crankshaft are better than those of the 3‐cylinder crankshaft, and the after‐forging elongation of the 4‐cylinder crankshaft can reach at approximately 16.6 %. Furthermore, the grain sizes evolution of 3‐cylinder crankshaft obtained by numerical simulations are basically consistent with the experimental grain size results, and it is feasible to predict and control the grain sizes’ evolution and mechanical properties of the crankshaft hot forging by using Deform‐3D.