PSI - Issue 28

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ScienceDirect

Procedia Structural Integrity 28 (2020) 1369–1377 Procedia Structural Integrity 00 (2020) 000–000 Procedia Structural Integrity 0 (2020) 000–000

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© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo Abstract The mixed-mode fracture toughness of a 42CrMo4 high-strength steel under mode I / II loading was investigated. The steel was processed in a steel casting simulator where it was poured through a spaghetti-type filter into a ceramic crucible. The machined compact tension shear specimens were heat treated in order to obtain the quenched and tempered state. The designs of the specimen and the loading device enabled testing at di ff erent loading angles leading to di ff erent ratios K I / K II . Strain gauges were applied in order to analyze the stress field around the crack tip. It was observed that the strain gauges can be reasonably applied to measure K I . However, large errors occurred during the measurement of K II . The specimens fractured in a brittle manner. However, no valid plane-strain fracture toughness was obtained. With increased loading angles, mode I fracture toughness decreased while mode II fracture toughness increased. Furthermore, it was found that stretch zone was flattened with increased loading angle. 2020 The Authors. Published by Elsevier B.V. is is an open access article under the CC BY-NC-ND license (http: // creativec mmons.org / licenses / by-nc-nd / 4.0 / ) r-review unde responsibility of the European St uctural Integr ty Society (ESIS) ExCo. Keywords: Fracture toughness; mixed-mode fracture; high-strength steel 1st Virtual European Conference on Fracture Experimental determination of toughness under mode I / II loading S. Henschel a, ∗ , F. Posselt a , S. Dudczig b , T. Wetzig b , C. G. Aneziris b , L. Krüger a a Institute of Materials Engineering, TU Bergakademie Freiberg, Gustav-Zeuner-Str. 5, D-09599 Freiberg, Germany b Institute of Ceramic, Glass and Construction Materials, TU Bergakademie Freiberg, Agricolastr. 17, D-09599 Freiberg, Germany Abstract The mixed-mode fracture toughness of a 42CrMo4 high-strength steel under mode I / II loading was investigated. The steel was processed in a steel casting simulator where it was poured through a spaghetti-type filter into a ceramic crucible. The machined compact tension shear specimens were heat treated in order to obtain the quenched and tempered state. The designs of the specimen and the loading device enabled testing at di ff erent loading angles leading to di ff erent ratios K I / K II . Strain gauges were applied in order to analyze the stress field around the crack tip. It was observed that the strain gauges can be reasonably applied to measure K I . However, large errors occurred during the measurement of K II . The specimens fractured in a brittle manner. However, no valid plane-strain fracture toughness was obtained. With increased loading angles, mode I fracture toughness decreased while mode II fracture toughness increased. Furthermore, it was found that stretch zone was flattened with increased loading angle. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo. Keywords: Fracture toughness; mixed-mode fracture; high-strength steel 1st Virtual European Conference on Fracture Experimental determination of toughness under mode I / II loading S. Henschel a, ∗ , F. Posselt a , S. Dudczig b , T. Wetzig b , C. G. Aneziris b , L. Krüger a a Institute of Materials Engineering, TU Bergakademie Freiberg, Gustav-Zeuner-Str. 5, D-09599 Freiberg, Germany b Institute of Ceramic, Glass and Construction Materials, TU Bergakademie Freiberg, Agricolastr. 17, D-09599 Freiberg, Germany In practice, pure mode I fracture is a special case of the more general mixed-mode fracture. One possibility of mixed-mode fracture is by combining mode I (tensile loading of the crack faces) and mode II (in-plane shear loading of the crack faces). In order to ensure safety of cracked components, fracture toughness values need to be measured experimentally. Benitz and Richard (1981) and Banks-Sills et al. (1982) suggested specimens and loading devices for measuring the mixed-mode fracture toughness. Later publications of them show improvements, e.g. concerning the connection of specimen and loading device by bolts (Banks-Sills and Arcan (1986)) and a specimen geometry modification for less brittle materials (Richard (1985)). Richard’s setup (Richard (1985)) was further considered since favorable dimensions are suggested. Furthermore, a reasonable variety of loading angles can be used in order to obtain di ff erent ratios K I / K II . In practice, pure mode I fracture is a special case of the more general mixed-mode fracture. One possibility of mixed-mode fracture is by combining mode I (tensile loading of the crack faces) and mode II (in-plane shear loading of the crack faces). In order to ensure safety of cracked components, fracture toughness values need to be measured experimentally. Benitz and Richard (1981) and Banks-Sills et al. (1982) suggested specimens and loading devices for measuring the mixed-mode fracture toughness. Later publications of them show improvements, e.g. concerning the connection of specimen and loading device by bolts (Banks-Sills and Arcan (1986)) and a specimen geometry modification for less brittle materials (Richard (1985)). Richard’s setup (Richard (1985)) was further considered since favorable dimensions are suggested. Furthermore, a reasonable variety of loading angles can be used in order to obtain di ff erent ratios K I / K II . 1. Introduction 1. Introduction

∗ Corresponding author. Tel.: + 49 3731 39-3452; fax: + 49 3731 39-3703. E-mail address: sebastian.henschel@iwt.tu-freiberg.de ∗ Corresponding author. Tel.: + 49 3731 39-3452; fax: + 49 3731 39-3703. E-mail address: sebastian.henschel@iwt.tu-freiberg.de

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo 10.1016/j.prostr.2020.10.108 2210-7843 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review u der responsibility of the European Structural Integrity Society (ESIS) ExCo. 2210-7843 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo.