Abstract
In this work, gas tungsten arc welding (GTAW) was used to repair ZG06Cr13Ni4Mo martensitic stainless steel. Repair welding occurred either once or twice. The changes in the microstructure and properties of the repair welded joints were characterized by optical microscope (OM), scanning electron microscope (SEM), electron backscattering diffraction (EBSD), tensile and impact tests. The effects of reversed austenite in repair welded joints on microstructure and mechanical properties were studied. The results show that the microstructure of the welded joint after repair welding consists of a large amount of martensite (M) and a small amount of reversed austenite (A), and the reversed austenite is distributed at the boundary of martensite lath in fine strips. With the increase in the number of welding repairs, the content of reversed austenite in the welded joint increases. The microstructure in the repair welded joints is gradually refined, the microstructure in the once and twice repaired joints is 45.2% and 65.1% finer than that in the casting base metal, respectively. The reversed austenite presented in the repair welded joints decreases the tensile strength by 4.8% and 6.7%, increases the yield strength by 21.3% and 26.4%, and increases the elongation by 25% and 56%, respectively, compared with the casting base metal. In addition, the reversed austenite mainly nucleates and grows at the boundary of lath martensite. The refinement of the martensite structure was due to the generation of reversed austenite and the refinement of original austenite grain by the welding thermal cycle. After repair welding, the reverse austenite appeared in the repair welded joints and the tensile strength decreased slightly, but the plastic toughness was significantly improved, which was conducive to the subsequent service process.
Highlights
ZG06Cr13Ni4Mo is a super martensitic stainless steel
In this paper, we study the change in microstructure and mechanical properties of ZG06Cr13Ni4Mo martensitic stainless steel welded joint under different numbers of welding repairs, and we explore the relationship between the number of welding repairs, the content of reversed austenite and mechanical properties to provide corresponding theoretical guidance for production practice
We found that in the original casting with all-martensite microstructure and no detected austenite phase, the reversed austenite generated during repair welding is distributed at the grain boundary of the original austenite and the boundary of the martensite laths
Summary
ZG06Cr13Ni4Mo is a super martensitic stainless steel. It has numerous applications in hydropower, nuclear power and petrochemical industries [1]. 1950s, when Swiss scientists reduced the carbon content to less than 0.07%, while adding nickel (ω = 4%–6%) and molybdenum (ω ≤ 2.5%) This steel improves the weldability, and overcomes the shortage of plasticity and toughness of traditional martensitic stainless steel, the difficulty of cold processing and forming. This steel has good weldability, strength and toughness and corrosion resistance [2,3,4]. The ZG06Cr13Ni4Mo low-carbon martensitic stainless steel has excellent casting, forging, welding and machining properties [6]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
