Heat treatment from the main group "Changing material properties" includes processes or process chains for thermal, thermo-chemical and thermo-mechanical treatment of workpieces. The component properties, which are important in many applications, are adjusted by specific heating and cooling phases and the resulting phase transformations via the microstructure composition, the residual stress state and the hardness.
In heat treatment, a fundamental distinction is made between processes that cause a radical structural transformation and processes that only cause a transformation on the surface of a workpiece. The first-mentioned processes include annealing and hardening, i.e. thermal processes. The second-mentioned processes count as diffusion and coating processes as well as thermochemical processes.
The thermochemical surface hardening processes are mainly characterised in series production by a significant increase in surface hardness and lifetime at low unit costs. On the one hand, it is intended to achieve high surface layer hardness in order to minimize the wear. On the other hand, the microstructure and residual stress depth profiles are specifically adjusted, which usually leads to an extension of the durability.
The current research focus is the optimization of heat treatment processes for components that are difficult to access. The adjustment of mixed microstructures to improve the mechanical properties is another important aspect. The goal is to improve fatigue properties compared to the conventional quenching and tempering processes by adjusting different microstructure components.
We are currently working on the following topics in the heat treatment of steels and aluminium alloys:
- Carbo-PM: Carbonitriding process simulation of powder metallurgical parts
- Tailored bainitic-martensitic microstructures by means of inductive surface hardening for AISI4140
Internal Intensive Quenching (IIQ): Ideal heat treatment for hard accessible component sections
- DFG Project T-TRIP: Investigation of transformation induced plasticity during precipitation formation in quenched and tempered steels and maraging steels
- Inductive hardening and tempering of graded porous powder metallurgical steels
- ZIM project “BainMa Shaft”: Development of a sequentially induction-hardened cardan shaft with a high-strength surface layer by locally load-dependent bainite-martensite components and low-impact post-processing to increase lifetime