This article describes the studies of the mechanical properties of the martensitic structure of C45 steel, obtained as a result of heat treatment. This steel was subjected to high tempering, within the temperature range of 500 ÷ 700°C (every 50°C) and for various exposure times, from 15 minutes to 23 hours. Moreover, martensitic steel was subjected to tests by quenching at a temperature of 850°C for 20 minutes and then tempering it for 1 hour, within the temperature range of 50 ÷ 800°C (every 50°C). The resulting steel samples were subjected to strength tests, that is, to tensile and hardness tests and also to tests on the micro-structure. The results of these studies are presented and discussed, in detail, in terms of their practical application.
Purpose: In this study, the effect of heat treatment on the microstructure and mechanical properties of 42CrMo4 steel were investigated. Design/methodology/approach: The samples were annealed at 860°C for 120 min. followed by oil quenching and then tempered at temperatures between 480 and 570°C for 120 min. The microstructure of untreated 42CrMo4 steel mainly consists of pearlite and ferrite whereas the microstructure was found to be as a martensitic structure with a quenching process. Findings: The results showed that there is an increase in yield stress, ultimate tensile stress, hardness and impact energy, while elongation decreases at the end of the quenching process. Conversely, yield stress, ultimate tensile stress and hardness decrease slightly with the increasing of tempering temperature, while elongation and impact energy increase. Research limitations/implications: Other types of steels can be heat treated in a wider temperature range and the results can be compared. Practical implications: It is a highly effective method for improving the mechanical properties of heat treatment materials. Originality/value: A relationship between the mechanical properties and the microstructure of materials can be developed. The heat treatment is an effective method for this process.
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W artykule przedstawiono rezultaty badań eksperymentalnych związanych z opracowywaniem superwytrzymałej stali przeznaczonej do zaawansowanych zastosowań konstrukcyjnych, m.in. w przemyśle lotniczym. W oparciu o badania mikrostruktury, własności mechanicznych i odporności na pękanie opracowano alternatywne sposoby obróbki cieplnej w stosunku do tradycyjnego hartowania z odpuszczaniem, takie jak wysokotemperaturowe austenityzowanie i obróbka na dolny bainit.
EN
The results of experimental study aimed at the development of steels for advanced structural applications, e.g. in the aircraft industry, were presented. For the quenched and tempered 40HSN3MWA steel, heat treatments alternative to the conventional quenching and tempering have been developed. The heat treatment involved high temperature austenitizing or transformation to microstructure of lower bainite, both leading to very high strength and fracture toughness.
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