Induction Heat Treatment and Materials Durability Laboratory

- Rolling Contact Fatigue (RCF) test bench, designed in-house, is used to study the behaviour of materials and components subjected to repeated loading in rolling contact, such as bearings, gears and railway wheels. Its main objective is to produce characteristic crack failures: micropitting or spalling. As a result of the tests performed on this bench, the useful life is determined and/or surface treatments or lubricants are validated to improve the performance of the component / probe. This test stand has two test configurations, 3-rod bar and ball-on-plane, which allow tests to be carried out on flat or cylindrical specimens, and has extensive control capabilities: load (up to 150 kN), speed (up to 2700 rpm), lubricant flow (up to 1.5 litres/min), temperature (cooled by lubricant cooler) and monitoring capabilities for temperatures (in specimen, lubricant inlet and outlet), current (to monitor torque evolution) and vibration (RSM and FFT indicators). It also has a fault diagnosis system with automatic detection and stopping of probe failure through the vibration indicators.
- MTS modular test stand: 2 MTS hydraulic cylinders (50 kN and 150 kN), HPU hydraulic unit (MTS SilentFlo 515) and MTS Flex 40 test controller. Bed 4500 x 2000 mm with brackets and gantry. Allows accelerated fatigue testing of mechanical and structural components.

• The software tool registered as iKonPro® is used for the evaluation of subsurface fatigue caused by rolling contact fatigue in rolling bearings. This tool integrates the knowledge generated and published on this mechanical failure mode in doctoral theses, addressing all the problems involved: 1) the evaluation of the temporal distribution of loads on rolling elements, 2) the extraction of subsurface stresses in time, and 3) the counting of stress cycles and damage calculation.
• The software tool registered as ikGear® is used to evaluate wear fatigue damage and TFF (Tooth Flank Fracture) in gears based on time series of torque and driving gear position. This tool is currently based on two stages: 1) finite element pre-processing to determine the residual stress map from the manufacturing process and the stress response at different positions and load levels, and 2) fatigue damage processing using cycle counting and damage accumulation.

- Vickers microhardness tester FM-810 with automatic loading mechanism (variable load 10 g-1 kg) with digital trace measurement. Possibility of Vickers, Knoop and Brinell tests.
- Residual stress analyser MTS3000-RESTAN by Hole Drilling Method, which allows the residual stresses resulting from manufacturing processes, such as induction heat treatments, to be obtained. It is an automatic system for measuring residual stresses by the hole-drilling method. Tests can be performed according to ASTM E837 for uniform and non-uniform stress states. Furthermore, by using an appropriate acquisition strategy (fine hole-drilling) and a suitable analysis method (Integral, Incremental or by Influence Functions), it is possible to reconstruct the residual stress progression in the thickness already in the first microns of depth.
- Laboratory equipment for the preparation of metallographic samples (metallographic cutting, crimping, polishing and metallographic etching) for the analysis of microstructures in metallic materials.

Proprietary subroutine implementation models for numerical simulation for induction heat treatments (such as induction quenching and tempering) where electromagnetic-thermal (induction heating) and thermal-mechanical-metallurgical (heat treatment) physics are coupled. These models are capable of predicting temperature evolution, hardened layer pattern and hardness, microstructure, residual stresses and distortions produced by induction heat treatment.

Laboratory bench of our own design for induction hardening and tempering of parts. It allows heat treatments to be carried out under controlled and monitored conditions, either with rotation and/or by means of linear sliding (scanning). It has power (up to 30 kW) and frequency (range of 0,5-50 kHz) regulation. It also has a closed-circuit cooling system with adjustable flow, the usual coolant being a mixture of water and polymer. It has two pyrometers and thermocouple measurements can be recorded for temperature control. It allows real-time monitoring of the sensorised variables, such as inductor temperatures, currents and voltage.