Nanostructured Carbide-Free Bainite Formation in Low Carbon Steel  

作　　者：Hamid Mousalou Sasan Yazdani Naghi Parvini Ahmadi Behzad Avishan 

机构地区：[1]Faculty of Materials Engineering,Sahand University of Technology,P.O.Box:51335/1996,Tabriz,Iran [2]Department of Materials Engineering,Azarbayan Shahid Madani University,Tabriz,Iran

出　　处：《Acta Metallurgica Sinica(English Letters)》2020年第12期1635-1644,共10页金属学报（英文版）

摘　　要：It is an important challenge to reduce the carbon content in nanostructured bainitic steels for commercialization purposes while still being able to gain the desired microstructural characteristics in nanoscale and not to deteriorate the strength–ductility combinations.That is the point at which an appropriate heat treatment procedure design would be an important parameter.This article aims to investigate how to obtain nanostructured bainite in steel with 0.26 wt%carbon content by applying multi-step austempering procedures.One-,two-and three-step austempering processes have been implemented,and proper heat treatment temperatures and approaches were selected based on dilatometry tests.Results indicated that it has become possible to achieve bainitic ferrites and austenite fi lms with overall thicknesses of 164,145 and 132 nm and 134,105 and 90 nm at the end of one-,two-and three-step austempering heat treatments,respectively.Meanwhile,microstructural characteristics resulted in enhanced mechanical properties with ultimate tensile strength(UTS)of 1435,1455 and 1428 MPa in combination with elongation levels of 15.4,13.6 and 11.4%after implementing those heat treatments.Finally,it has been shown that applying the multi-step austempering heat treatments resulted in enhanced yield strength and impact toughness values due to the microstructural characteristics and proper heat treatment procedure design.

关 键 词：BAINITE Multi-step austempering AUSTENITE Mechanical properties Impact toughness 

分 类 号：TG142.31[一般工业技术—材料科学与工程]