In this study, we developed the heat treatment simulation that can consider the difference in phase transformation behavior and strength characteristics in response to heterogeneous composition by calculating the TTT diagram and stress-strain curve corresponding to the composition at each position of the simulation model.

This study presents a method to reduce thermal distortion in tubular automotive stabilizer bars by replacing batch furnace heating with individual conductive heating and implementing a press-quenching technique with a seven-point clamping fixture. Using finite element analysis, researchers optimized the clamping system to maintain critical dimensional tolerances while addressing the challenges of inhomogeneous temperature distribution through a programmed current profile. Statistical analysis confirmed significant improvement in dimensional stability compared to conventional quenching.

Samples from forged and heat-treated steel products with known quench crack histories have been mapped in order to study a possible relation between banding segregation and quench cracking. The products were medium carbon low alloy steels produced by ingot and continuous casting. EDS X-ray mapping was used to characterize the banding pattern and tensile testing revealed corresponding properties. The experimental procedures are described in the paper along with test results and conclusions.

Previous work was reported on the induction hardening process for a 1541 steel axle shaft. This presentation compares the previous results with the stress formation dynamics in the same shaft made from steels with lower hardenability. Hardened using a scan heating method and a trailing PAG spray quench, several steels having lower hardenability were modeled using the same heating schedule so that the depth of austenite formation is similar in all cases. During spray quenching, the hardened case is shallower as steel hardenability is reduced. This leads to differences in the magnitude of compressive and tensile stresses and their distributions. In turn, the potential for internal cracking is reduced as the stress transition zone is altered by the thickness of the diffusive phase layer between the martensitic case and the ferrite-pearlite core of the shaft. The next step is to investigate these effects on the torque carrying ability of the shaft.

Press quenching is a specialized quenching technique used in heat treating operations to minimize the distortion of complex components such as spiral bevel gears and high quality bearing races. The quenching machine is designed to control the geometrical characteristics of components such as out-of-round, flatness, and (if the tooling is designed to accommodate it) taper. The achievement of final dimensional tolerances is accomplished through a trial and error process where the incoming machined sizes of the components are adjusted based upon measurement data taken from the initial sets of quenched and tempered components that have already been processed through the press quenching operation. Oil flow rates can be altered during the different stages of the quenching cycle, and through the use of specialized tooling the oil flow pathways can be selectively adjusted to meter the oil flow towards specific areas of the part surface while baffling it away from others in order to provide a more uniform overall quench. Complex metallurgical changes take place during austenitizing and quenching, resulting in corresponding mechanical property changes. Accompanying these changes are the generation of thermal and transformation induced stresses, which produce in-process and final residual stresses. During press quenching, dimensional restrictions add additional complexity to the combined effects of thermal and mechanical process sensitivities on these stresses. And if the stresses are severe enough, quench cracking can result. In this investigation the quench cracking of an asymmetrical AISI 52100 bearing ring is evaluated through physical experiments and through corresponding heat treatment process modeling using DANTE. The effects of quench rate, die load pulsing, and several other process variables are examined experimentally and/or analytically to illustrate how they can impact the resulting stresses generated during the press quenching operation.

Quench cracks became a challenge in large serial production of martensitic components. The geometry is simple, and concentrations of stresses from the geometry itself were not indicated by numerical simulation. Grain boundary ferrite is presented in the component surface from where the cracks start. An example from another application is interesting to consider; titanium grade 5. Grain boundary alpha on prior beta grain boundaries is not accepted for aerospace applications. The volume for plastic deformation in the phases along the grain boundaries is restricted. The ductile part of the fracture indicates forces from unbalanced quenching and elevated temperature at time of crack start. The general focus for improvement will be overcritical surface temperature, vapor phase break and mix of turbulent/lamellar flow. More effective quenching around the whole component is, in this case, assumed to be better than slower quenching.