A STUDY OF NOTCH TOUGHNESS AND WELD SOFTENING IN SUBMERGED-ARC WELD HEAT-AFFECTED ZONE FOR Q&T HIGH TENSILE STEEL ( REPORT 2) (EFFECT OF PRE-TREATMENT AND MICROSTRUCTURE ON NOTCH TOUGHNESS)

Of the metallurgical factors influencing the notch toughness of submerged-arc weld heat-affected zone, study was made on the effect of pre-treatment of base metal on notch toughness of coarse grained heat-affected zone, especially for steel containing strong carbide or nitride forming elements. Also the effect of cooling rate and microstructure on the notch toughness of duplicated weld heat-affected zone is smaller, compared to that of steel temperature 1350 degrees C. Notch toughness of duplicated weld heat-affected zone in solution-treated steel is lower in general. In steels containing niobium, vanadium and titanium, notch toughness of duplicated weld heat-affected zone is higher in rapidly cooled cycles, when the base metal is normalized or quenched, both followed by spheroidizing treatment. Austenite grain size in heat-affected zone is smaller, comparing to that of steel free from such elements. However, the effect was hardly observed in duplicated weld heat-affected zone cooled at the slower rate of 7C/sec at 540 degrees C. In ferritic steels such as Steel A to H, slower the cooling rate of duplicated weld heat-affected zone, the lower the notch toughness greatly. While low alloy high tensile steel such as Steel I to L, cooling rate dependency of notch toughness is smaller, i.e., low alloy high strength steel with higher hardenability has superior notch toughness in weld heat-affected zone in the case of large input welding. According to the results for quenched and tempered Steel I, The highest notch toughness is obtained when the weld heat-affected zone is cooled, keeping up with the C sub f time of the CCT diagram. Especially the peak of notch toughness is achieved by mixed structure of lower bainite and Martensite. In Japanese.

• Corporate Authors:

  Japan Welding Society

  1-11, Sakuma-cho, Kanda, Chiyoda-ku
  Tokyo,   Japan 
• Authors:
  • Sato, M
  • Kawahara, E
• Publication Date: 1971

Media Info

• Pagination: p. 64-73
• Serial:
  • Japan Welding Society, Journal of
  • Volume: 40
  • Issue Number: 4
  • Publisher: Japan Welding Society

Subject/Index Terms

• TRT Terms: Metal heating; Notching (Cutting); Strength of materials; Welds
• Uncontrolled Terms: Heat treatment
• Old TRIS Terms: Notch toughness; Weld properties
• Subject Areas: Marine Transportation; Materials;

Filing Info

• Accession Number: 00032635
• Record Type: Publication
• Source Agency: Ship Structure Committee
• Files: TRIS
• Created Date: Apr 21 1972 12:00AM