Quenching is one of the primary processes to improve mechanical properties in steels, particularly hardness. Quenching is well established for different geometries of individually treated steel components; while in-steam quenching of large diameter continuously cast steel bar has several specific features which are difficult and costly to experimentally optimize. The end-quench Jominy test has been used extensively to study the hardenability of different steel grades. Different numerical, analytical, and empirical models have been developed to simulate the Jominy process and to understand quenching of steels. However, it is not straight forward to translate experimental data from Jominy test on instream quenched large diameter continuously cast products. Therefore, in this work, coupled thermal, mechanical, and metallurgical models were used to simulate the end-quench Jominy test and in-stream quenched industrial round billets with a goal to obtain similarity of experimental structure and properties for both quenched products. For this purpose, finite element analysis (FEA) was employed using the software FORGE (by Transvalor). Used thermophysical properties were generated by JMATPro software. The evolution of microstructure during quenching and resulting hardness were simulated for AISI 4130, and AISI 4140 steel grades. The cooling rates at different positions in the Jominy bar were determined by simulation and compared to experimental. After verification and validation, the FEA simulation was utilized to predict different phases and hardness at different conditions in industry produced round billets. Additionally, relations between Jominy positions and radial positions in the billet were established allowing us to predict structure and properties in inline quenched continuously cast bar having different diameters.

Numerical model of controlled cooling in production of steel hot rolled bars was developed. By numerical model of controlled cooling is possible to predict a transient temperature field, microstructure evolution and hardness of rectangular steel bars during their cooling in cooling beds. The numerical model of transient temperature field is based on control volume method. The algorithm for prediction of hardness and microstructure distribution in steel bars is based on continues cooling transformation, (CCT) diagrams and real chemical composition. The numerical model and algorithm is completed to solve problems in controlled cooling of hot rolled bars in cooling beds. The controlled cooling are performed by special placement of hot rolled bars on cooling beds. Numerical model and computer program was experimentally verified by simulation of real industrial production of low alloyed steel bars. The verification of developed numerical model was performed by comparison of simulated hardness with experimentally evaluated results.

Blade curving due to quenching in the Japanese sword has been recognized by swordsmiths through the ages. In the late 1920s, Hattori noted that the sword curving is induced from not only martensitic transformation expansion in the near-edge region but also non-uniform elastic and plastic strains distributed in the section, based on his experimental results using cylindrical specimens. Our research for an updated explanation on the subject prepared Japanese sword (JS) type specimens made of the same steel and process as the Japanese sword, and model JS (MJS) type specimens with the almost same shape as the JS type specimens, which were machined from commercial carbon steel and austenite stainless steel bars. All specimens quenched by a swordsmith using the traditional way showed a usual curved shape with different curvatures. Curving, temperature, hardness, metallic structure and residual stress measurements for the specimens were performed to prepare their future simulation works.

The potential for improving mechanical properties of steels via thermal processing (e.g. austenization and rapid quenching) through modified phase equilibria in the presence of a high magnetic field has been the subject of numerous recent works [1,2]. In this study, torsional fatigue performance of case-carburized SAE 8620 re-austenitized and quenched inside of a 9 Tesla, 5” diameter superconducting magnet is reviewed. Conventional atmosphere furnace carburized hardened and tempered, and in-situ magnetic field re-hardened and tempered material (Induction Thermo-Magnetic Processing, or “ITMP”) was subjected to fully-reversed torsional loading. Both Special Bar Quality (SBQ) bar and forged SBQ bar steel in carburized conditions were heat treated and mechanically tested. There was no measurable difference in fatigue behavior for either condition when comparing conventionally heat-treated and ITMP re-hardened populations.

Developing heat treat systems and control plans that produce consistent direct harden (quench and temper) results with a high percent martensite and the corresponding proper mechanical properties is challenging for large components or large batch sizes. In this study, large section bars in alloys suitable for water quenching were austenitized and quenched under controlled flow conditions. The bars were primarily examined by several as-quenched hardness versus depth traverses in order to be sure localized non-martensitic regions (soft areas) would be detected. The tests allowed for some key insights into defining the adequacy of direct harden water quench systems, including the idea of agitation thresholds required for each alloy grade or hardenability level to prevent soft spots (spotty hardening) on large section steel components.

Atmospheric case hardening of powertrain components may cause internal oxidation and thus reduce hardenability at the surface zone. This may affect the fatigue strength, which restricts the maximum cyclic load on steel components and hence is a major impediment for powertrain development and design. Here we have investigated the effect of furnace gas atmosphere composition and quenching path on fatigue properties of powertrain components. The results show that the detrimental effect of internal oxidation on fatigue may be compensated for by altering of the furnace atmosphere. Moreover, it is shown that the quenching path below the martensite start temperature also has an impact on the fatigue properties. These experiments were done in a full-scale industrial furnace on steel bars in 16MnCr5 and 20NiMo9-7F.

Microalloying of medium carbon bar steels is a common practice for a number of traditional components; however, use of vanadium microalloyed steels is expanding into applications beyond their original designed use as controlled cooled forged and hot rolled products and into heat treated components. As a result, there is uncertainty regarding the influence of vanadium on the properties of heat treated components, specifically the effect of rapid heat treating such as induction hardening. In the current study, the torsional fatigue behavior of hot rolled and scan induction hardened 1045 and 10V45 bars are examined and evaluated at effective case depths of 25, 32, and 44% of the radius. Torsional fatigue tests were conducted at a stress ratio of 0.1 and shear stress amplitudes of 550, 600, and 650 MPa. Cycles to failure are compared to an empirical model, which accounts for case depth as well as carbon content.