• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to previous page

Clarification and evaluation of high temperature deterioration in high efficiency weld joint

Research Project

Project/Area Number 10650071
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Materials/Mechanics of materials
Research InstitutionIBARAKI UNIVERSITY

Principal Investigator

KONOSU Shinji  IBARAKI Univ. Fuc. of Engineering Associate Professor, 工学部, 助教授 (90091686)

Project Period (FY) 1998 – 1999
Project Status Completed (Fiscal Year 1999)
Budget Amount *help
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥1,900,000 (Direct Cost: ¥1,900,000)
KeywordsCreep / Austenitic stainless steel / Weld joint
Research Abstract

1) In the case of the FCA weld metal (which contained large amounts of bismuth, i.e., >0.02%), bismuth segregated as a single substance at the grain boundaries to a depth of about 15 A. The presence of this bismuth led to intergranular fracturing and very marked reductions in creep fracture elongation.
2) There was no large difference in creep fracture elongation between the SMA and FCA weld metals, both of which contained no bismuth.
3) Creep crack growth rate of the high Bi content FCA weld metal was extremely rapid compared with that of the SMA and FCA weld metals containing no bismuth and in addition to adversely affecting creep elongation properties, the bismuth which segregated at the grain boundaries was also highly deleterious with regard to creep crack growth properties.
4) It has been found that the creep crack growth rate tends to be higher (about 2.5 to 3-fold) in cases where sigma phases have adequately precipitated as a result of high-temperature aging than in cases where they have not. This is because creep cracks propagate preferentially through the austenite-sigma interfaces at the dendrite boundaries.
5) Accordingly, both the bismuth which segregates at the grain boundaries and the sigma phase which precipitates at the grain boundaries serve as important factors that increase creep crack growth rate. The grain boundary segregation of bismuth is a larger influence factor than sigma phase precipitation in increasing the creep crack growth rate. Therefore, large amounts of bismuth (approximately 0.02%) should be avoided in connection with Type 308 stainless welds and the delta ferrite content of the weld metal should be suppressed as much as possible for elevated temperature service.

Report

(3 results)
  • 1999 Annual Research Report   Final Research Report Summary
  • 1998 Annual Research Report
  • Research Products

    (6 results)

All Other

All Publications (6 results)

  • [Publications] S.Konosu et al.: "Creep Crack Growth Properties of Type 308 Austenitic Stainless Weld Metals"Welding Journal. 77. 322-327 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S.Konosu et al.: "Effects of pretest aging on creep crack growth properties of type 308 austenitic stainless steel weld metals"Engineering Failure Analysis. (to be published).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. Konosu, A. Hashimoto, H. Mashiba, M. Takeshima and T. Ohtsuka: "Creep Crack Growth Properties of Type308 Austenitic Stainless Weld Metals"Welding Journal. Vol.77, No.8. 322-327 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. Konosu, H. Mashiba, M. Takeshima and T. Ohtsuka: "Effects of pretest aging on creep crack growth properties of type 308 austenitic stainless steel weld metals"Engineering Failure Analysis. (to be published).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S.Konosu et al.: "Creep Crack Growth Properties of Type 308 Austenitic Stainless weld Metals"Welding Journal. 77・8. 322-327 (1998)

    • Related Report
      1999 Annual Research Report
  • [Publications] S.Konosu et al.: "Effects of pretest aging on Creep crack growth properties of type 308 austenitic stainless steel weld metals"Engineering Failure Analysis. (to be published).

    • Related Report
      1999 Annual Research Report

URL: 

Published: 1998-04-01   Modified: 2016-04-21  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi