Change in the microstructure and mechanical properties of drawn pearlitic steel with low-temperature aging

38th Risø International Symposium on Materials Science

Hirakami, D.^1 ; Ushioda, K.^2,3 ; Manabe, T.^1 ; Noguchi, K.^4 ; Takai, K.^5 ; Hata, Y.^6 ; Hata, S.^7 ; Nakashima, H.^7

Bar and Wire Rod Research Lab., Steel Research Laboratories, Nippon Steel and Sumitomo Metal Corporation, Japan^1

Technical Research and Development Bureau, Nippon Steel and Sumitomo Metal Corporation, Japan^2

Graduate School of Natural Science and Technology, Kanazawa University, Japan^3

Sophia University, Japan^4

Department of Engineering and Applied Science, Faculty of Science and Technology, Sophia University, Japan^5

Kyushu University, Japan^6

Department of Electrical and Materials Science, Faculty of Engineering Sciences Kyushu University, Japan^7

关键词: Embrittlement resistance;    Low temperature aging;    Low temperatures;    Microstructure and mechanical properties;    Pearlitic steels;    Precession electron diffractions;    Relaxation stress;    Thermal desorption analysis;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/219/1/012026/pdf
DOI  :  10.1088/1757-899X/219/1/012026

来源: IOP

【 摘 要 】

Hydrogen embrittlement is a serious problem in high-strength steels. Drawn pearlitic steel shows excellent resistance to hydrogen embrittlement despite its high strength, and aging treatment at a low temperature can simultaneously improve its strength and hydrogen-embrittlement resistance. To clarify the mechanism for this we have used thermal desorption analysis (TDA) and the newly developed precession electron diffraction analysis method in the transmission electron microscope. After aging at 100 °C for 10 min, the amount of hydrogen seen amount on the TDA curve reduced at around 100 °C. In contrast, when aging was performed at 300 °C, the hydrogen amount further reduced at around 100 °C and the unevenly deformed lamellar ferrite zone was locally recovered. For the samples that were aged at the low temperature, we confirmed that their yield strength and relaxation stress ratios increased simultaneously with improvement in the hydrogen-embrittlement property. We infer that segregation of carbon or formation of very fine carbide in dislocations during aging is the cause of these behaviors.