Effect of tempering temperature on microstructure and properties of 20Cr1Mo1VTiB bolt steel

doi:10.13251/j.issn.0254-6051.2023.07.020

Abstract

Abstract: Microstructure and mechanical properties of 20Cr1Mo1VTiB bolt steel at different tempering temperatures were studied by means of SEM, EBSD, TEM, tensile tester, impact tester and hardness tester. The results show that the width of lath bainite in the steel increases and the bainite transforms into polygonal ferrite gradually with the increase of tempering temperature. Meanwhile, the increasing tempering temperature also promotes the coarsening and morphology transformation of carbides precipitation. The VC on grain boundary grows, the acicular M₃C grows into short rod-like and the tetragonal TiC grows and transforms into spherical. By testing the mechanical properties, it is recommended that the bolts should be tempered at 690 ℃×4 h and the nuts should be tempered at 720 ℃×4 h to obtain an ideal hardness matching.

Key words: 20Cr1Mo1VTiB steel, microstructure, carbide, bainite

CLC Number:

TG156.5

Gong Xueting, Zhao Jiqing, Yang Gang, Yang Bin. Effect of tempering temperature on microstructure and properties of 20Cr1Mo1VTiB bolt steel[J]. Heat Treatment of Metals, 2023, 48(7): 117-123.

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