The performance of surface hardened parts is a major issue in automotive and aerospace industries. There is, therefore, a strong need of hardening companies to improve the quality control of their products by introducing new measurement systems which allow for non-destructive, non-contacting hardness profile measurements as an alternative to the presently used destructive inspection methods. It is the aim of this project to develop a contact free, non-destructive photothermal measurement methodology. This will result in the design of a photothermal hardness measurement system which will be an important step to achieve a 100 % on-line production control. The network is proposed for Thematic Networks Type 2 as an Implementation Phase Network. The measurement method will be developed for surface hardened steel samples Radiometric photothermal measurement methods will be optimised for hardness testing and applicability in an industrial environment. Calibration curves relating hardness to thermal diffusivity changes will be elaborated and recommendations for the use of the radiometric photothermal method for a specific hardening treatment will be given. An important task is the further development of existing mathematical inversion schemes for calculating the thermal diffusivity profile from photothermal data. Using the calibration curves in combination with microstructural studies, this will result in a methodology for hardness profile measurements. The partnership consists of end-users of hardness quality control systems who also will supply samples from their production lines. Small and medium sized enterprises (SMEs) as well as a major European car manufacturer collaborate with research institutes specialised in photothermal measurements and materials science. It is expected that the innovative hardening measurement technique will improve the competitivity of the industrial partners by increasing the reliability of hardened products by an on-line quality control.
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