The Role of Retained Austenite and Its Carbon Concentration on Elongation of Low Temperature Bainitic Steels at Different Austenitising Temperature
Baoqi Dong,
Tingping Hou,
Wen Zhou,
Guohong Zhang,
Kaiming Wu
Affiliations
Baoqi Dong
The State Key Laboratory for Refractories and Metallurgy, Hubei Collaborative Innovation Center on Advanced Steels, International Research Institute for Steel Technology, Wuhan University of Science and Technology, Wuhan 430081, China
Tingping Hou
The State Key Laboratory for Refractories and Metallurgy, Hubei Collaborative Innovation Center on Advanced Steels, International Research Institute for Steel Technology, Wuhan University of Science and Technology, Wuhan 430081, China
Wen Zhou
The State Key Laboratory for Refractories and Metallurgy, Hubei Collaborative Innovation Center on Advanced Steels, International Research Institute for Steel Technology, Wuhan University of Science and Technology, Wuhan 430081, China
Guohong Zhang
The State Key Laboratory for Refractories and Metallurgy, Hubei Collaborative Innovation Center on Advanced Steels, International Research Institute for Steel Technology, Wuhan University of Science and Technology, Wuhan 430081, China
Kaiming Wu
The State Key Laboratory for Refractories and Metallurgy, Hubei Collaborative Innovation Center on Advanced Steels, International Research Institute for Steel Technology, Wuhan University of Science and Technology, Wuhan 430081, China
The influence of austenitising temperature on the tensile properties of low temperature bainitic steel was investigated. With the increasing austenitising temperature, a significant change of elongation was found between 850 and 950 °C, which was changed from 1.0 ± 0.5 to 10.7 ± 2.0%; while there was a slight increase between 950 to 1050 °C (11.2 ± 1.5%). By characterising the retained austenite at necking and matrix, we found that the elongation is obviously correlated with the retained austenite content, and also determined by the volume change of retained austenite during the tensile test. The transformation induced plasticity (TRIP) effect, which contributes to the improve elongation, almost did not occur at 850 °C due to the relatively low volume percentage of retained austenite and its high carbon concentration, which resulted in a very low martensite transformation temperature. With the austenitising, the temperature was increased up to 950 and 1050 °C, and a large volume percentage of retained austenite was observed in the matrix. Meanwhile, a considerable amount of retained austenite has occurred by the TRIP effect because of a moderate carbon content.
