The dissolution of carbides during the heating to the quenching temperature has a significant effect on the martensite oversaturation and the resulting mechanical properties. The kinetics of dissolution can be influenced by various external factors. This work deals with monitoring the carbide dissolution utilizing dilatometer analysis. The austenitization of 100CrMnSi6-4 bearing steel in two initial states was compared—after accelerated spheroidization annealing and conventional soft annealing. The main objective was to determine the amount of undissolved cementite during austenitization in the temperature range where only austenite and cementite are present in the structure. The austenitization temperature determines the degree of cementite dissolution and, consequently, the carbon content in austenite and thus the final properties after quenching. The cementite dissolution was quantified from dilatometric curves and image analysis.

Various structure states before quenching significantly influence final mechanical properties as well as the dispersion of chemical composition at the same steel grade. Therefore heat treatment with mechanical properties is specified in the technical delivery conditions. Even if the heat treatment is determined, different mechanical properties can be achieved. These differences are increasing in importance in high-strength applications like springs, cutting tools, safety, and load-bearing parts of automotive design ect. Because it has a direct impact on their lifetime. The structure consists of ferrite and cementite after spheroidization annealing prior quenching process. The cementite could be observed in various shapes, e.g. fine and large globular particles or the rest of the disintegrated lamellar shape. This article shows how these cementite morphologies affect the quenching behavior and final mechanical properties in high-strength spring steel 54SiCr6.

One of the concepts behind Generation IV reactors is a molten salt coolant system, where the materials for the reactor itself and for the primary and secondary circuit components are subjected to extreme chemical and thermal stresses. Due to the unavailability of these materials, a nickel–molybdenum alloy known as MoNiCr has been developed in the Czech Republic. This paper discusses the manufacturing process for the MoNiCr alloy, covering conventional casting technology, forming, powder atomization, additive manufacturing (AM) using the directed energy deposition (DED-LB) process, and final heat treatment. Special attention was given to the quality of the input powders for additive manufacturing, particularly regarding the optimization of the chemical composition, which significantly influenced the quality of the additively manufactured components. AM enables the realization of complex structural designs that are critical for energy applications, despite the high susceptibility of the MoNiCr alloy to solidification cracking. Through AM, a test body was successfully produced with a maximum defect rate of 0.03% and the following mechanical properties: a yield strength (YS) of 279 MPa, an ultimate tensile strength (UTS) of 602 MPa, and an elongation (El) of 51%.

The steel 51CrV4 is widely used for the production of springs. Materials research into spring steels aims to meet the requirements of the industry, which mainly concern high yield and tensile strengths. Ductility has to be retained as the strength is increased. Also, the resistance against brittle fracture is important, measured as fracture toughness. Enhancement of the mentioned mechanical properties can be accomplished by structural refinement. One possible way to refine the final quenched and tempered structure is to refine the soft annealed structure before quenching. The article is devoted to Accelerated Carbide Spheroidization and Refinement (ASR) with a comparison to conventional soft annealing (SA) in the 51CrV4 spring steel. Both spheroidization treatments (ASR by induction heating, and SA by electric furnace heating) led to different carbide particle sizes. The carbide refinement alters the material's behavior during quenching. Finer carbides dissolve more rapidly during austenitization at the quenching temperature. It is possible to lower the quenching temperature thanks to carbide refinement. Mechanical properties after hardening with different quenching temperatures were positively affected too.