The relationship between low-temperature toughness and secondary crack in low-carbon bainitic weld metals
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050 (China)
- Laboratory of Thermo Mechanical Metallurgy (LMTM), PX Group Chair, Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de la Maladière 71b, 2000 Neuchâtel (Switzerland)
Highlights: • The crack propagation plane was identified with the decreasing possibility of {110}/{100}, {112} and {123}. • Crack path deviates at some middle-angle misorientation boundaries with high strain concentration. • The most effective barrier to arrest crack in Ni0 and Ni2 is the boundaries of inter-Bain in a CPP packet, while in Ni4 the boundaries of inter-CPP and intra-Bain packets impede crack propagation. - Abstract: This paper aims to reveal the relationship among low-temperature toughness, microstructure and secondary crack from both microstructural and crystallographic perspectives. Instrumented Charpy tests were carried out in the upper platform, transition temperature range, as well as at lower temperatures. Quantitative fractographic analysis, microstructural characterization and secondary crack observation were conducted on half of the impact specimen. Crystallographic features were identified in the secondary crack proximity, e.g. variant selection, orientation relationship, cleavage plane of the corresponding crack matrix. Some results in literature are confirmed. Nickel addition is beneficial to hindering crack propagation as a result of microstructure improvement. The most effective barrier for crack propagation is high-angle misorientation boundaries between Bain packets and the boundaries of ferrite matrix with the microstructure of granular bainite. Additionally, high-angle misorientation boundaries between closed-packed plane packets arrest cracks in the mixed microstructure of fine lath bainite and intricate acicular ferrite. Most preferred crack propagation planes are {110} and {100} in our low carbon bainitic weld metals, with the decreasing possibility of {112} and {123}.
- OSTI ID:
- 22805879
- Journal Information:
- Materials Characterization, Journal Name: Materials Characterization Vol. 145; ISSN 1044-5803; ISSN MACHEX
- Country of Publication:
- United States
- Language:
- English
Similar Records
EBSD Analysis of Relationship Between Microstructural Features and Toughness of a Medium-Carbon Quenching and Partitioning Bainitic Steel
Characterization of coarse bainite transformation in low carbon steel during simulated welding thermal cycles