Abstract:The volume fraction of ferrite in the forged crankshaft of newly developed ferritic + pearlitic non-quenched and tempered steel C38+N2 is often difficult to meet the requirement of customers. Therefore, a small amount (0.022%) of microalloying element Nb was added to the steel and its effect on microstructure and mechanical properties after forging were investigated. The results showed that the addition of Nb can refine the grain size and post-forging microstructure, and significantly increase the ferrite content in the microstructure. The volume fraction of ferrite in the microstructure of simulated crankshaft forging can reach 20%, which was twice as high as that of non-Nb steel. After the Nb addition, the strength of the forged steel was almost unchanged or increases slightly, while the ductility especially the impact toughness were improved. The results of two schedules of simulated forging revealed that the as-forged microstructure of the Nb-added steel was slightly influenced by the changes of forging schedule and post-forging cooling rate, and the microstructure and mechanical properties meeting the requirements of users can be obtained in a wide forging window.
余大江, 高加强, 赵四新. Nb对C38+N2非调质钢组织和力学性能的影响[J]. 中国冶金, 2021, 31(5): 92-97.
YU Da-jiang, GAO Jia-qiang, ZHAO Si-xin. Effect of Nb on microstructure and mechanical properties of non-quenched and tempered steel C38+N2[J]. China Metallurgy, 2021, 31(5): 92-97.
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