Effect of Boron on the Microstructure and High Temperature Quasi-static Fracture Toughness of Heat Affected Zone in Heat-resistant Steel FB2

doi:10.3901/JME.2015.24.069

Abstract

Abstract: The quasi-static fracture toughness of heat affected zone(HAZ) of martensite heat-resistant steel FB2 at 450 ℃ is tested, indicating that the toughness of HAZ is at the same level of modified 9Cr-1Mo parent metal’s. It is found that there is no coarse grain zone in the HAZ, and the second phases precipitate in prior austenite grain and boundary homogeneously. It is also found that the precipitates in the grain boundaries are smaller than those within the grains. The fine grains and small precipitates in grain boundaries make contribution to the high toughness of HAZ. Boron plays an important role in the formation of special structure of HAZ with occupying the vacancies around precipitates, in which way the stability of precipitates is enhanced and the growing of austenite is affected.

Key words: boron, heat affected zone(HAZ), heat-resistant steel, quasi-static fracture toughness

LI Kejian, CAI Zhipeng, LI Yifei, PAN Jiluan, SUN Lingen. Effect of Boron on the Microstructure and High Temperature Quasi-static Fracture Toughness of Heat Affected Zone in Heat-resistant Steel FB2[J]. Journal of Mechanical Engineering, 2015, 51(24): 69-74.

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