Variations of fracture toughness and stress-strain curve of cold worked stainless steel and their influence on failure strength of cracked pipe

In order to assess failure probability of cracked components, it is important to know the variations of the material properties and their influence on the failure load assessment. In this study, variations of the fracture toughness and stress-strain curve were investigated for cold worked stainless...

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Main Author: Masayuki KAMAYA
Format: Article
Language:English
Published: The Japan Society of Mechanical Engineers 2016-06-01
Series:Mechanical Engineering Journal
Subjects:
Online Access:https://www.jstage.jst.go.jp/article/mej/3/6/3_16-00155/_pdf/-char/en
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author Masayuki KAMAYA
author_facet Masayuki KAMAYA
author_sort Masayuki KAMAYA
collection DOAJ
description In order to assess failure probability of cracked components, it is important to know the variations of the material properties and their influence on the failure load assessment. In this study, variations of the fracture toughness and stress-strain curve were investigated for cold worked stainless steel. The variations of the 0.2% proof and ultimate strengths obtained using 8 specimens of 20% cold worked stainless steel (CW20) were 77 MPa and 81 MPa, respectively. The respective variations were decreased to 13 and 21 MPa for 40% cold worked material (CW40). Namely, the variation in the tensile strength was decreased by hardening. The COVs (coefficients of variation) of fracture toughness were 7.3% and 16.7% for CW20 and CW40, respectively. Namely, the variation in the fracture toughness was increased by hardening. Then, in order to investigate the influence of the variations in the material properties on failure load of a cracked pipe, flaw assessments were performed for a cracked pipe subjected to a global bending load. Using the obtained material properties led to variation in the failure load. The variation in the failure load of the cracked pipe caused by the variation in the stress-strain curve was less than 1.5% for the COV. The variation in the failure load caused by fracture toughness variation was relatively large for CW40, although it was less than 2.0% for the maximum case. It was concluded that the hardening induced by cold working does not cause significant variation in the failure load of cracked stainless steel pipe.
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spelling doaj.art-fd06c83930524ec98521a6ceadb4715b2022-12-21T19:29:17ZengThe Japan Society of Mechanical EngineersMechanical Engineering Journal2187-97452016-06-013616-0015516-0015510.1299/mej.16-00155mejVariations of fracture toughness and stress-strain curve of cold worked stainless steel and their influence on failure strength of cracked pipeMasayuki KAMAYA0Institute of Nuclear Safety System, Inc.In order to assess failure probability of cracked components, it is important to know the variations of the material properties and their influence on the failure load assessment. In this study, variations of the fracture toughness and stress-strain curve were investigated for cold worked stainless steel. The variations of the 0.2% proof and ultimate strengths obtained using 8 specimens of 20% cold worked stainless steel (CW20) were 77 MPa and 81 MPa, respectively. The respective variations were decreased to 13 and 21 MPa for 40% cold worked material (CW40). Namely, the variation in the tensile strength was decreased by hardening. The COVs (coefficients of variation) of fracture toughness were 7.3% and 16.7% for CW20 and CW40, respectively. Namely, the variation in the fracture toughness was increased by hardening. Then, in order to investigate the influence of the variations in the material properties on failure load of a cracked pipe, flaw assessments were performed for a cracked pipe subjected to a global bending load. Using the obtained material properties led to variation in the failure load. The variation in the failure load of the cracked pipe caused by the variation in the stress-strain curve was less than 1.5% for the COV. The variation in the failure load caused by fracture toughness variation was relatively large for CW40, although it was less than 2.0% for the maximum case. It was concluded that the hardening induced by cold working does not cause significant variation in the failure load of cracked stainless steel pipe.https://www.jstage.jst.go.jp/article/mej/3/6/3_16-00155/_pdf/-char/enmaterial property variationfracture toughnessj-r curvetensile strengthfailure assessment curve
spellingShingle Masayuki KAMAYA
Variations of fracture toughness and stress-strain curve of cold worked stainless steel and their influence on failure strength of cracked pipe
Mechanical Engineering Journal
material property variation
fracture toughness
j-r curve
tensile strength
failure assessment curve
title Variations of fracture toughness and stress-strain curve of cold worked stainless steel and their influence on failure strength of cracked pipe
title_full Variations of fracture toughness and stress-strain curve of cold worked stainless steel and their influence on failure strength of cracked pipe
title_fullStr Variations of fracture toughness and stress-strain curve of cold worked stainless steel and their influence on failure strength of cracked pipe
title_full_unstemmed Variations of fracture toughness and stress-strain curve of cold worked stainless steel and their influence on failure strength of cracked pipe
title_short Variations of fracture toughness and stress-strain curve of cold worked stainless steel and their influence on failure strength of cracked pipe
title_sort variations of fracture toughness and stress strain curve of cold worked stainless steel and their influence on failure strength of cracked pipe
topic material property variation
fracture toughness
j-r curve
tensile strength
failure assessment curve
url https://www.jstage.jst.go.jp/article/mej/3/6/3_16-00155/_pdf/-char/en
work_keys_str_mv AT masayukikamaya variationsoffracturetoughnessandstressstraincurveofcoldworkedstainlesssteelandtheirinfluenceonfailurestrengthofcrackedpipe