Internal Intensive Quenching: Optimal Heat Treatment for inaccessible component areas

• Applicant: Professor Dr.-Ing. Volker Schulze
• Subject Area: Metallurgical, Thermal and Thermomechanical Treatment of Materials
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 299152500

In the course of this project a method to increase the life time of hydraulic components under an interior high pressure loading is developed. Such components find intensive usage in modern fuel-injection systems and have to withstand a cyclic pressure up to 4000 bar. To further increase the efficiency of such components there is a trend towards higher pressures in future systems while at the same time the components advance to more and more filigree structures due to the overall vehicle mass reduction. To sustain those changes in applied pressure with an equal component life time the properties of the base material have to be tailored during the production process towards an optimal microstructure. Recent methods for the local strain hardening of bore walls like drifting or autofrettage are based on the introduction of compressive residual stresses and if applicable small strain hardening effects in the bore hole wall. Compared to thermal methods the impact of these mechanisms on the component lifetime is very limited. On the other side most of the established thermal methods, e. g. case hardening, have difficulties with small bore diameters due to the restricted accessibility of the targeted areas. Therefore in this project the focus is directed towards the control and modification of the microstructure, residual stresses and strain hardening in a modified intensive quenching process based on martensitic hardening. The development of this process includes the efficient inductive heating of the part to austenization temperature followed by a local quenching with a high pressure water-air mixture to achieve an optimal near surface state of the bore hole. The newly developed process should first be tested on simple through-holes and then be transferred on more application oriented drilling intersections.

• DFG Programme: Research Grants
• Co-Investigators: Dr.-Ing. Stefan Dietrich; Dr.-Ing. Jens Gibmeier