Influence on quenchant performance during induction hardening

The cooling performance and heat transfer coefficients of polymers, used for induction hardening in showers, have been evaluated with regard to quench flow, temperature and concentration. Even apparently small deviations in cooling performance have a significant influence on residual stress state, even after tempering. The study was complemented with a benchmark study. In several cases used quenchants were found to deviate from fresh, newly blended, polymer quenchants. Even though the concentration seamed to be correct, according to Brix refractometer index, significant deviations in the quenching performance could be observed when analysing the cooling curves.