Study of the Impact of Multiple Weld Repairs and Associated Stress-Relief Annealing on Mechanical Properties at Elevated Temperatures of Large Components Made of the Low-Alloy Steel 16Mo3

• Published in: Praktische Metallographie Vol. 50; no. 11; pp. 728 - 738
• Main Authors: Giller, M., Lehmann, K.
• Format: Journal Article
• Language: English
• Published: München De Gruyter 15.11.2013; Hanser
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Joining, thermal cutting: metallurgical aspects; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Solidification; Welding; Welded joints; Annealing; Temperature; Welding; Mechanical properties; Low alloy steels; High temperature; Repair; Heat treatments
• ISSN: 0032-678X; 2195-8599
• DOI: 10.3139/147.110264

This paper is related to 16Mo3, a low-alloy steel typical in the manufacture of large welded steel casings of heavy-duty gas turbine engines. The usual practice in manufacturing is to stress relieve these housings after fabrication welding. If, however, weld imperfections are detected by non-destructive testing, weld repairs are performed, followed by additional stress-relief heat treatments. The methods applied were used to detect possible embrittlement by secondary carbide precipitation and to finally draw conclusions on material changes. The critical area of a weld is the heat affected zone. In this area a worsening of the stress condition in connection with a change in carbide precipitation and thus a decrease in creep rupture strength occurs. A concrete alloy composition and heat treatment adapted to the precipitation behavior are important, because they determine the type, amount and distribution of the resulting carbides [1, 2].