INVESTIGATION OF THE TOUGHNESS OF LOW CARBON TEMPERED MARTENSITE IN THE SURFACE OF Ni-Cr-Mo-B ULTRA-HEAVY PLATE STEEL
WANG Xiaoyong1, PAN Tao1, WANG Hua2, SU Hang1,LI Xiangyang3, CAO Xingzhong4
1. Division of Structural Materials, Central Iron and Steel Research Institute, Beijing 100081
2. Angang Steel Company Limited, Anshan 114021
3. China Iron and Steel Research Institute Group, Beijing 100081
4. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049
Cite this article:
WANG Xiaoyong, PAN Tao, WANG Hua, SU Hang,LI Xiangyang, CAO Xingzhong. INVESTIGATION OF THE TOUGHNESS OF LOW CARBON TEMPERED MARTENSITE IN THE SURFACE OF Ni-Cr-Mo-B ULTRA-HEAVY PLATE STEEL. Acta Metall Sin, 2012, 48(4): 401-406.
Abstract Low carbon tempered martensite structures in the surface of Ni-Cr-Mo-B ultra-heavy plate steel was studied. The toughness at different locations in the surface zone was investigated by impact testing, and the sub-microstructures, such as packets and blocks of the martensite, at different distances (3, 15 and 25 mm) from the surface were observed by OM, SEM and electron backscattered diffraction (EBSD), and the dislocation density were tested by XRD and positron annihilation spectroscopy (PAS). The results indicate that the toughness of the tested steel in the 10 mm from the surface deteriorates sharply, which is mainly due to the bigger packet and block size and higher dislocation density in the tempered martensite.