Bonding Strength of 12Cr-0.4C/Low Carbon Steel (LCS) Weld Joint After Solid Solution Heat Treatment

• Published in: JOM (1989) 2024-08, Vol.76 (8), p.4285-4298
• Main Authors: Zhu, Wenjun, Wang, Yong, Zhou, Jianjun, Mao, Chengrong, Li, Yongcun, Gao, Sheng
• Format: Article
• Language: English
• Subjects: Bainite; Bonded joints; Bonding strength; Carbides; Carbon steel; Chemistry/Food Science; Cooling; Earth Sciences; Engineering; Environment; Ferrite; Fractures; Grain boundaries; Hardness; Heat affected zone; Heat treating; Low carbon steels; Martensite; Microstructural analysis; Microstructure; Microstructure and Defect Development During Rapid Solidification; Pearlite; Physics; Rare gases; Retained austenite; Solid solutions; Solution heat treatment; Tensile strength; Tensile tests; Welded joints
• ISSN: 1047-4838; 1543-1851
• DOI: 10.1007/s11837-024-06506-5

The metal inert gas (MIG) technique plays a vital role in enhancing the durability and lifespan of 20 steel under harsh operating conditions across various industries. A strong bond is crucial for preventing joint separation. Fe-based materials with appropriate Cr/C exhibit high compatibility with carbon steel bonding. Solid solutions can improve the situation faced by MIG-treated joints. In this work, weld joints were manufactured by MIG, and half of them were treated with a solid solution, and. after the analysis of microstructure and properties, it was found that the untreated fused zone (FZ) showed good forming quality with martensite, retained austenite, and had a carbide microstructure. The solid solution eliminated the retained austenite and exhibited an even hardness. The untreated heat-affected zone had a complex microstructure, dominating upper bainite, and discrepancy-shape ferrite. The untreated group's base material (BM) consisted of grain boundary martensite, ferrite, and pearlite in a matrix, while the solid-solution group's hardness was similar. Tensile tests revealed that the untreated group had a yield strength of 639 MPa, while the solid solution group gained 339 MPa. The untreated group in BM fractures was caused by grain boundary martensite, while the solid-solution group in FZ fractures was caused by α ′ and carbides.