Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa

Pekka Nevasmaa, Päivi Karjalainen-Roikonen, Anssi Laukkanen, T. Nykänen, A. Ameri, T. Björk, T. Limnell, J. Kuoppala

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

Abstract

The fracture behaviour of S960 steel in different conditions, i.e as-delivered, cold strained, cold strained and artificially aged, has been studied using small-scale fracture mechanics and Charpy V testing as well as tests on large-scale U-beams and cold-formed rectangular hollow sections. At room temperature and -40 deg C, fracture resistance testing indicated overall ductile behaviour. Regarding brittle fracture, the T0 reference temperature for the as-received material was around -50 deg C. Artificial ageing alone increased this temperature only slightly, but cold-straining and artificial ageing together raised T0 (and T28J) by almost 50 deg C. For the strength level studied, the FITNET correlation between T0 and T28J leads to severely un-conservative KJC estimates, indicating that KJC needs to be measured directly. T0 estimates based on fracture mechanics tests using small-scale 3-point bend specimens were clearly conservative in relation to the large-scale U-beam behaviour due to different constraints. Shear fracture occurred in the U-beam tests as a result of the small plate thickness; however, this led to only a 10 % decrease in the load-bearing capacity from the theoretical maximum load. Quasi-static bending tests on welded fatigue-cracked cold-formed rectangular hollow sections at -40 deg C showed good agreement with nonlinear FEA calculations using the J-integral approach. Both large-scale test variants showed that brittle cleavage fracture will not become the dominant fracture mode in the welded beam constructions studied, provided the service temperature does not fall below -50 deg C.
Original languageEnglish
Title of host publicationProceedings
Subtitle of host publication2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010
Place of PublicationMilano
Number of pages14
Publication statusPublished - 2010
MoE publication typeB3 Non-refereed article in conference proceedings

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High strength steel
Yield stress
Brittle fracture
Fracture mechanics
Loads (forces)
Aging of materials
Temperature
Bending tests
Testing
Bearing capacity
Fracture toughness
Fatigue of materials
Finite element method
Steel

Cite this

Nevasmaa, P., Karjalainen-Roikonen, P., Laukkanen, A., Nykänen, T., Ameri, A., Björk, T., ... Kuoppala, J. (2010). Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. In Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010 Milano.
Nevasmaa, Pekka ; Karjalainen-Roikonen, Päivi ; Laukkanen, Anssi ; Nykänen, T. ; Ameri, A. ; Björk, T. ; Limnell, T. ; Kuoppala, J. / Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010. Milano, 2010.
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title = "Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa",
abstract = "The fracture behaviour of S960 steel in different conditions, i.e as-delivered, cold strained, cold strained and artificially aged, has been studied using small-scale fracture mechanics and Charpy V testing as well as tests on large-scale U-beams and cold-formed rectangular hollow sections. At room temperature and -40 deg C, fracture resistance testing indicated overall ductile behaviour. Regarding brittle fracture, the T0 reference temperature for the as-received material was around -50 deg C. Artificial ageing alone increased this temperature only slightly, but cold-straining and artificial ageing together raised T0 (and T28J) by almost 50 deg C. For the strength level studied, the FITNET correlation between T0 and T28J leads to severely un-conservative KJC estimates, indicating that KJC needs to be measured directly. T0 estimates based on fracture mechanics tests using small-scale 3-point bend specimens were clearly conservative in relation to the large-scale U-beam behaviour due to different constraints. Shear fracture occurred in the U-beam tests as a result of the small plate thickness; however, this led to only a 10 {\%} decrease in the load-bearing capacity from the theoretical maximum load. Quasi-static bending tests on welded fatigue-cracked cold-formed rectangular hollow sections at -40 deg C showed good agreement with nonlinear FEA calculations using the J-integral approach. Both large-scale test variants showed that brittle cleavage fracture will not become the dominant fracture mode in the welded beam constructions studied, provided the service temperature does not fall below -50 deg C.",
author = "Pekka Nevasmaa and P{\"a}ivi Karjalainen-Roikonen and Anssi Laukkanen and T. Nyk{\"a}nen and A. Ameri and T. Bj{\"o}rk and T. Limnell and J. Kuoppala",
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Nevasmaa, P, Karjalainen-Roikonen, P, Laukkanen, A, Nykänen, T, Ameri, A, Björk, T, Limnell, T & Kuoppala, J 2010, Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. in Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010. Milano.

Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. / Nevasmaa, Pekka; Karjalainen-Roikonen, Päivi; Laukkanen, Anssi; Nykänen, T.; Ameri, A.; Björk, T.; Limnell, T.; Kuoppala, J.

Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010. Milano, 2010.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

TY - GEN

T1 - Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa

AU - Nevasmaa, Pekka

AU - Karjalainen-Roikonen, Päivi

AU - Laukkanen, Anssi

AU - Nykänen, T.

AU - Ameri, A.

AU - Björk, T.

AU - Limnell, T.

AU - Kuoppala, J.

PY - 2010

Y1 - 2010

N2 - The fracture behaviour of S960 steel in different conditions, i.e as-delivered, cold strained, cold strained and artificially aged, has been studied using small-scale fracture mechanics and Charpy V testing as well as tests on large-scale U-beams and cold-formed rectangular hollow sections. At room temperature and -40 deg C, fracture resistance testing indicated overall ductile behaviour. Regarding brittle fracture, the T0 reference temperature for the as-received material was around -50 deg C. Artificial ageing alone increased this temperature only slightly, but cold-straining and artificial ageing together raised T0 (and T28J) by almost 50 deg C. For the strength level studied, the FITNET correlation between T0 and T28J leads to severely un-conservative KJC estimates, indicating that KJC needs to be measured directly. T0 estimates based on fracture mechanics tests using small-scale 3-point bend specimens were clearly conservative in relation to the large-scale U-beam behaviour due to different constraints. Shear fracture occurred in the U-beam tests as a result of the small plate thickness; however, this led to only a 10 % decrease in the load-bearing capacity from the theoretical maximum load. Quasi-static bending tests on welded fatigue-cracked cold-formed rectangular hollow sections at -40 deg C showed good agreement with nonlinear FEA calculations using the J-integral approach. Both large-scale test variants showed that brittle cleavage fracture will not become the dominant fracture mode in the welded beam constructions studied, provided the service temperature does not fall below -50 deg C.

AB - The fracture behaviour of S960 steel in different conditions, i.e as-delivered, cold strained, cold strained and artificially aged, has been studied using small-scale fracture mechanics and Charpy V testing as well as tests on large-scale U-beams and cold-formed rectangular hollow sections. At room temperature and -40 deg C, fracture resistance testing indicated overall ductile behaviour. Regarding brittle fracture, the T0 reference temperature for the as-received material was around -50 deg C. Artificial ageing alone increased this temperature only slightly, but cold-straining and artificial ageing together raised T0 (and T28J) by almost 50 deg C. For the strength level studied, the FITNET correlation between T0 and T28J leads to severely un-conservative KJC estimates, indicating that KJC needs to be measured directly. T0 estimates based on fracture mechanics tests using small-scale 3-point bend specimens were clearly conservative in relation to the large-scale U-beam behaviour due to different constraints. Shear fracture occurred in the U-beam tests as a result of the small plate thickness; however, this led to only a 10 % decrease in the load-bearing capacity from the theoretical maximum load. Quasi-static bending tests on welded fatigue-cracked cold-formed rectangular hollow sections at -40 deg C showed good agreement with nonlinear FEA calculations using the J-integral approach. Both large-scale test variants showed that brittle cleavage fracture will not become the dominant fracture mode in the welded beam constructions studied, provided the service temperature does not fall below -50 deg C.

M3 - Conference article in proceedings

SN - 978-88-85298-79-8

BT - Proceedings

CY - Milano

ER -

Nevasmaa P, Karjalainen-Roikonen P, Laukkanen A, Nykänen T, Ameri A, Björk T et al. Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. In Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010. Milano. 2010