Effect of Ce on microstructure and mechanical properties of 30MnNbRE steel after quenching and tempering

doi:10.13251/j.issn.0254-6051.2023.09.025

Abstract

Abstract: Effect of rare earth element Ce on microstructure and mechanical properties of 30MnNbRE steel after quenching and tempering were studied by means of scanning electron microscope, X-ray diffractometer, hardness test, tensile test and impact test. The results show that Ce promotes the solution of Nb in γ-Fe and increases the hardness after quenching, while Ce promotes the precipitation of nanoscale (FeMnNb)₃C with a size of about 40 nm during tempering, resulting in a significant precipitation strengthening effect. At the same time, the pinning effect of (FeMnNb)₃C precipitated between laths refines the thickness of the martensite laths, and finally obtain a uniform and refined nanoscale martensite lath structure. When the addition amount of Ce is 0.01%, the mechanical properties of the 30MnNbRE steel are the best. After tempering at 450 ℃, the hardness can reach 42.6 HRC, the tensile strength increases to 1135 MPa, the fine spherical inclusions with a size of about 1 μm are obtained, concurrently the elongation after fracture is the largest which reaches 13.8%, and the fracture shows ductile fracture characteristics.

Key words: Ce, quenching and tempering, microstructure, mechanical properties, precipitation, rare earth inclusions

CLC Number:

TG335

Song Cao, Wang Xiaodong, Bao Xirong, Chen Lin, Tang Xuejiao. Effect of Ce on microstructure and mechanical properties of 30MnNbRE steel after quenching and tempering[J]. Heat Treatment of Metals, 2023, 48(9): 143-149.

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