• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2016, Vol. 52 ›› Issue (10): 67-74.doi: 10.3901/JME.2016.10.067

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Effect of Deformation and Cooling on the Phase Transformation of Martensite for B1500HS Boron Steel

LI Huiping1, HE Lianfang1, YANG Xiaodan1, ZHAO Guoqun2   

  1. 1. School of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590;
    2. Key Laboratory for Liquid-solid Structure Evolution &
    Processing of Materials of Ministry of Education, Shandong University, Jinan 250061
  • Online:2016-05-15 Published:2016-05-15

Abstract: Some samples of B1500HS boron steel austenizing at 900 ℃ are compressed about 10%, 20%, 30% and 40% at a constant strain rate by Gleeble 1500D thermo-mechanical simulator. The deformed samples are cooled at the rate of 50 ℃/s, 40 ℃/s and 25 ℃/s, the effects of deformation and cooling rate on the phase-transformation temperature, micro-structure, micro-hardness and retained austenite are researched. The results show that, the start and finish temperatures of martensite phase-transformation rise with increasing the deformation degree at the same cooling rate. The size of martensite microstructure becomes smaller, less twin martensite and more lath martensite are produced in the microstructure with increasing the deformation degree. The increase of deformation and cooling rate are both helpful to reduce the volume fraction of retained austenite in the samples of B1500HS steel. The continuous cooling transformation diagrams of B1500HS steel moves to left due to the deformation. The critical cooling rate for the undeformed austenite of B1500HS steel not transformed into bainite is approximately 25 ℃/s. If the deformation degree of B1500HS steel specimen is more than 30 %, bainite can be produced in the microstructure at the cooling rate of 25 ℃/s.

Key words: boron steel, deformation, microstructure, phase transformation

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