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Microstructures, Heat Treatment, and Properties of Boron‐Alloyed Tool Steels
Author(s) -
Lentz Jonathan,
Röttger Arne,
Theisen Werner
Publication year - 2020
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.201900416
Subject(s) - materials science , hardenability , eutectic system , metallurgy , boride , microstructure , tempering , boron , hot isostatic pressing , chromium , alloy , chemistry , organic chemistry
To enable the development of novel Fe–C–B–Cr and Fe–C–B–Cr–Mo cold work tool steels, the microstructures and hardness‐tempering behaviors of hypoeutectic laboratory melts are investigated. The results show that increasing Cr content enhances the thermodynamic stability of the ultrahard M 2 B borides. The formation of carboborides is suppressed by adjusting the B/(C + B) ratio, Cr content, and austenitization temperature. A secondary hardenability at 500 °C is achieved by Mo addition. In addition, Mo stabilizes the M 23 (C,B) 6 phase and at higher contents the M 3 B 2 boride. Based on these investigations, Fe0.4C1B–Cr alloys are designed which, inspired by the microstructure of the steel X153CrMoV12‐1, feature a α′‐Fe hardenable matrix but 15 vol% of eutectic M 2 B borides instead of M 7 C 3 for wear protection. The Fe0.4C1B–Cr steels are produced by casting and hot rolling as well as powder metallurgy and hot isostatic pressing. The (tribo‐) mechanical properties are investigated and compared with X153CrMoV12‐1. Fracture toughness, bending strength, wear resistance, and hardness of the novel Fe0.4C1B–Cr alloys are found to be similar or superior to the steel X153CrMoV12‐1, at decreased material cost.