Heat treatment process of new air-cooling bainitic steel for shovel teeth

doi:10.13251/j.issn.0254-6051.2020.08.035

Abstract

Abstract: In order to solve the problem of short service life of shovel teeth, the new bainitic steel and its heat treatment process were studied. The chemical composition and phase transition points of the bainitic steel were tested by spark direct reading spectrometer and thermal dilatometer. Effect of normalizing temperature, tempering temperature and tempering time on the toughness of the bainitic steel was studied by orthogonal test method, and the optimal heat treatment process was determined. Microstructure, phase composition ratio and hardness of bainitic steel for shovel teeth were measured by means of scanning electron microscopy, Image-J software, X-ray diffractometer and digital microhardness tester. The results show that the most important factor affecting the impact toughness of the bainitic steel is the normalizing temperature, then the tempering temperature and the tempering time in order. The optimal heat treatment process is normalizing at 1080 ℃+tempering at 250 ℃ for 90 min, by which the bainitic steel obtains a good combination of toughness (18.45 J) and hardness (46.85 HRC), and the content of martensite and retained austenite in the microstructure is 23.985% and 9.850%, respectively.

Key words: shovel teeth, bainitic steel, heat treatment, microstructure, properties

CLC Number:

TG161

Zheng Lili, An Shengli, Peng Jun, Zhang Fang, Gao Zhanyong, Jiao Haidong. Heat treatment process of new air-cooling bainitic steel for shovel teeth[J]. Heat Treatment of Metals, 2020, 45(8): 179-184.

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