International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This study investigated the effect of cold plastic deformation at Bridgman anvil chamber temperature on the hardness and wear resistance of X160CrMoV12 steel using hardness testing, X-ray diffraction (XRD), abrasive grinding wear (AEMW) testing, optical examination, and scanning electron microscopy (SEM). Three batches of samples were prepared for the experiment: I – hardened, II – hardened and then tempered at 600°C for 1.5 hours, III – hardened and then plastically deformed. The samples were hardened at three temperatures: 1100, 1150, and 1200 °C. The highest amount of retained austenite, reaching 69.02%, was observed when hardening at 1200°C, while at lower temperatures, 17.36% and 38.14% were formed, respectively. After hardening (batch II), the amount of retained austenite decreased proportionally by approximately 7 times for each hardening temperature. The effect of plastic deformation (batch III) is observed by analysing the hardness of samples from the surface to the depth, reaching an average hardening depth of 0.08 mm. To check how well it holds up to wear, the surfaces of three test batches were tested using an abrasive grinding test with a load of 5N. Hardened and plastically deformed specimens showed greater resistance to abrasion than hardened and tempered specimens. The results confirmed that the optimal hardening temperature for achieving maximum wear resistance of this steel is 1100°C.

Modern armor steels are essential in safeguarding military and civilian assets from ballistic threats. This paper provides a comprehensive classification of contemporary armor steels, examining their material properties, including hardness, impact resistance, and the influence of chemical composition, particularly carbon equivalent (CE), on their performance. The classification considers chemical composition, alloying elements, and mechanical properties, with a focus on their ballistic effectiveness and suitability for various armored platforms. Additionally, the paper delves into the historical evolution of armor steel, tracing its origins from early military applications to the sophisticated alloys used today. It also highlights the importance of MIL-DTL specifications in establishing a standardized language for armor steel grades, ensuring uniformity in quality and performance across the defense sector. Furthermore, the paper discusses the role of heat treatment procedures, such as quenching and tempering, in influencing the microstructure and mechanical properties of armor steels, directly affecting their resistance to penetration and impact. Through a review of armor steel classifications, historical context, and their technological advancements, this paper offers valuable insights into the ongoing efforts to improve the performance and reliability of armored materials.

Phase transformations in metals have a major influence on the material behaviour in several common engineering applications. Steels exhibiting enhanced response to transformation-induced plasticity (e. g. high strength TRIP-steels for automotive production) are examples of the important role martensite formation can play. An externally stressed specimen in the process of a phase transformation may show a significant nonlinear behaviour, which is known as transformation plasticity. Even under an externally applied load stress with the corresponding equivalent stress being small in relation to the “normal” yield stress of the material, plastic deformation occurs.
An aim of a research was to determine relaxation and transformation plasticity properties of alloyed tool steel while is tempered at elevated temperatures and for different tempering duration.

The article deals with the investigation of plastic deformations of carburized medium carbon stainless steel after quenching and tempering. After carburization the specimens were heated at 1020 °C temperature and then air quenched. At the process of air quenching the specimens were bent within the temperature dropping interval approximately from 550 °C to room temperature. The bending caused tension or compression in different parts of the specimen, so interstitial distortion was formed. As the bending stress was much lower than the yield stress, the specimen didn’t bend during the first minutes of experiment, and then started bending during the martensitic transformation (transformation plasticity effect). The curved quenched specimens then were tempered at temperatures 200, 300, 400, 500, 600 and 700 °C for 1 hour and the deflection of specimen after each tempering was measured.

The results showed different influence of tension and compression on transformations occurring in steel during quenching and tempering. The tempering temperature effect on self-deformation of curved specimen was revealed.

Basic idea in this metallographic investigation is checking the effect of induction (surface) quenching of produced part, two-side lever made of 42CrMo4 steel. This part is build in railway wagon. According its production assignation it has to be surface hardened just in some positions. Formerly surface hardness of this part was realized by chemical-heat treatment i.e. case hardening of 16MnCr5 steel. But because of specific form of the part and increased britlness which appear in the thinnest parts of lever (between the rounded opening and the surface) and idea was obtained to change the case hardening with induction quenching. Efficiency of performed induction quenching i.e. hardness values and depth of quenched layer was controlled by optical microscopy and hardness measurement.