Temperature Dependence of Fracture Characteristics of Variously Heat-Treated Grades of Ultra-High-Strength Steel: Experimental and Modelling
| Autor: | Jan Cupera, Jaroslav Pokluda, Jana Horníková, Ivo Dlouhý, Marta Kianicová, Pavel Šandera |
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| Rok vydání: | 2021 |
| Předmět: |
modelling fracture
Technology Materials science Charpy impact test tensile characteristics Article fracture toughness Stress (mechanics) Fracture toughness Ultimate tensile strength General Materials Science Composite material temperature dependence Austenite Microscopy QC120-168.85 QH201-278.5 technology industry and agriculture ultra-high steel grades Atmospheric temperature range Engineering (General). Civil engineering (General) TK1-9971 Descriptive and experimental mechanics Martensite Fracture (geology) Electrical engineering. Electronics. Nuclear engineering TA1-2040 |
| Zdroj: | Materials Volume 14 Issue 19 Materials . 2021, vol. 14, issue 19, p. 1-28. Materials, Vol 14, Iss 5875, p 5875 (2021) |
| ISSN: | 1996-1944 |
| DOI: | 10.3390/ma14195875 |
| Popis: | The temperature dependence of tensile characteristics and fracture toughness of the standardly heat-treated low-alloyed steel OCHN3MFA along with three additionally heat-treated grades was experimentally studied. In the temperature range of ⟨−196 22⟩ °C, all the additional heat treatments transferred the standard steel from a high- to ultra-high strength levels even with improved tensile ductility characteristics. This could be explained by a reduction of the inclusion content, refinement of the martensitic blocks, ductile retained austenite content, and homogenization of the shape ratio of martensitic laths as revealed by metallographic, X-ray, and EBSD techniques. On the other hand, the values of the fracture toughness of all grades were found to be comparable in the whole temperature range as the cause of a high stress triaxiality in the pre-cracked Charpy V-notch samples. The values of the fracture toughness of the standard steel grade could be predicted well using the fracture model proposed by Pokluda et al. based on the tensile characteristics. Such a prediction failed in the case of additionally heat-treated grades due to the different temperature dependence of the fracture mechanisms occurring in the tensile and fracture-toughness tests. While the tensile samples fractured in a ductile-dimple mode at all temperatures, the fracture-toughness specimens exhibited a transition from the ductile to quasi-brittle fracture mode with decreasing temperature. This transition could be interpreted in terms of a transfer from the model proposed by Rice and Johnson to the model of Tvergaard and Hutchinson. |
| Databáze: | OpenAIRE |
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