scholarly journals Effect of Isothermal Heat Treatment on the Microstructure and Mechanical Properties of Medium-Carbon Bainitic Steels

2018 ◽  
Vol 28 (9) ◽  
pp. 522-527 ◽  
Author(s):  
Ji-Min Lee ◽  
Sang-In Lee ◽  
Hyeon-Seok Lim ◽  
Byoungchul Hwang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Isothermal Heat Treatment ◽  
Medium Carbon ◽  
Microstructure And Mechanical Properties ◽  
Bainitic Steels

scholarly journals Effect of Heat Treatment on Microstructure and Mechanical Properties of New Cold-Rolled Automotive Steels

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1414
Author(s):  
Fei Huang ◽  
Jian Chen ◽  
Zhangqi Ge ◽  
Junliang Li ◽  
Yongqiang Wang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Testing Machine ◽  
Second Phase ◽  
Isothermal Heat Treatment ◽  
Austenitizing Temperature ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Microstructure And Mechanical Properties ◽  
Cold Rolled

The effect of austenitizing temperature and aging treatment on the microstructure and mechanical properties of two new cold-rolled automotive steel plates (20Mn2Cr and 20Mn2CrNb) was investigated by using isothermal heat treatment, optical microscope, scanning electron microscope, microhardness tester, and tensile testing machine. The results show that as the austenitizing temperature increased, the original austenite grain sizes of both steels increased. The original austenite grain size of 20Mn2CrNb was smaller than that of 20Mn2Cr. The microhardness of 20Mn2CrNb gradually decreased with increasing aging temperature, while the hardness of 20Mn2Cr varied irregularly. The mechanical properties of 20Mn2Cr were better than those of 20Mn2CrNb under the same heat-treatment process. The effect of heat treatment on microstructure and mechanical properties was related to the martensite content, dislocation density, and precipitation of second-phase particles.

Microstructure and Mechanical Properties of a Nb-Microalloyed Medium Carbon Steel Treated by Quenching-Partitioning Process

2012 ◽  
Vol 531-532 ◽  
pp. 596-599
Author(s):  
Kai Zhang ◽  
Shang Wen Lu ◽  
Yao Hui Ou ◽  
Xiao Dong Wang ◽  
Ning Zhong
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Electron Microscope ◽  
Carbon Steel ◽  
Retained Austenite ◽  
High Strength ◽  
Medium Carbon Steel ◽  
Orientation Relationships ◽  
Medium Carbon ◽  
Microstructure And Mechanical Properties

The recently developed “quenching and partitioning” heat treatment and “quenching-partitioning-tempering” heat treatment are novel processing technologies, which are designed for achieving advanced high strength steels (AHSS) with combination of high strength and adequate ductility. In present study, a medium carbon steel containing Nb was subjected to the Q-P-T process, and both the microstructure and mechanical properties was studied. The experimental results show that the Nb-microalloyed steel demonstrates high tensile strength and relatively high elongation. The microstructure of the steel was investigated in terms of scanning electron microscope and transmission electron microscope, and the results indicate that the Q-P-T steel consist of fine martensite laths with dispersive carbide precipitates and the film-like interlath retained austenite. The orientation relationships between martensite and retained austenite is as well-known Kurdjurmov-Sachs relationship and Nishiyama-Wasserman relationship.

scholarly journals Effect of Deformation on Microstructure and Mechanical Properties of Medium Carbon Steel During Heat Treatment Process

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Yan Peng ◽  
Caiyi Liu ◽  
Ningning Wang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Carbon Steel ◽  
Heating Temperature ◽  
Lath Martensite ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Experimental Steel ◽  
Microstructure And Mechanical Properties ◽  
Strength And Plasticity

AbstractThe current research of the Q-P and Q-P-T process has been focused on controlling the heating temperature and holding time, or adding alloy elements into the steel to induce precipitation strengthening and improve the strength and plasticity of the steel. In this article, based on a quenching-partitioning-tempering (Q-P-T) process combined with a hot deformation technology, a deforming-quenching-partitioning-tempering (D-Q-P-T) process was applied to medium carbon steel. The effect of the heat treatment parameters on the microstructure and mechanical properties of experimental steel under deformation was studied. Through use of a scanning electron microscope (SEM), transmission electron microscopy (TEM) and tensile tests, the optimal heat treatment conditions for realizing high strength and plasticity that meet the safety requirements were obtained. The mechanism for the D-Q-P-T process to improve the strength and plasticity of experimental steel was discussed. A multiphase composite structure of lath martensite and retained austenite was obtained. Compared with the Q-P-T process, use of the D-Q-P-T process can increase the strength of steel by 57.77 MPa and the elongation by 5%. This study proposes a method to improve the strength and plasticity of steel.

scholarly journals Microstructure and Mechanical Properties of Cast and Hot-Rolled Medium-Carbon Steels under Isothermal Heat-Treatment Conditions

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1950
Author(s):  
Byungsue Shin ◽  
Kwangyuk Kim ◽  
Sung Yi ◽  
Sanggyu Choi ◽  
Soongkeun Hyun
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cast Steel ◽  
Bainitic Ferrite ◽  
Medium Carbon Steel ◽  
Treatment Temperature ◽  
Isothermal Heat Treatment ◽  
Medium Carbon ◽  
Treatment Conditions ◽  
Hot Rolled

In this study, the changes in the microstructure and mechanical properties during isothermal heat treatment of cast steel before and after hot deformation were investigated using medium-carbon steel with low alloy content. The microstructural characteristics of the cast and hot-rolled medium-carbon steel under isothermal heat-treatment conditions were examined using optical microscopy and scanning electron microscopy in conjunction with electron backscatter diffraction. The variation in the mechanical properties was evaluated using Rockwell hardness and tensile tests. After maintaining an austenitizing condition at 1200 °C for 30 min, an isothermal heat treatment was performed in the range 350–500 °C, followed by rapid cooling with water. Both the cast steel and hot-rolled steel did not completely transform into bainitic ferrite during isothermal heat treatment. The partially untransformed microstructure was a mixture of martensite and acicular ferrite. At 500 °C, the prior austenite phase changed to Widmanstätten ferrite and pearlite. At 450 °C, bainitic ferrite and cementite were coarsened by the coalescence of ferrite and subsequent diffusive growth. The mechanical properties increased as the isothermal heat-treatment temperature decreased, and the hardness of the cast steel was generally higher than that of the hot-rolled steel. Hardness and strength showed similar trends, and overall mechanical properties tend to decrease as the isothermal heat-treatment temperature increases, but there are slight differences depending on complex factors such as various phase fractions and grain size.

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