/ 53 BOILING REGIMES DURING DIRECT QUENCHING Physically, the most challenging quenching approach is submersion (or direct) quenching where reheated components are submerged in the water pool. Initially, film boiling slows down the heat removal, followed by nucleate boiling and finally single phase cooling after the solid has cooled down beneath the saturation temperature of the quenchant. Predicting different boiling modes and the transition is the key. AVL FIRE® has proven to be an accurate and reliable numerical tool in numerous test configurations and full complexity cases, such as cylinder heads. The quenching process is affected by solid piece orientation, initial solid temperature, water temperature and more, therefore accurate prediction of local temperature histories within the structure is crucial for final prediction of residual stresses resulting from the production process. THERMAL STRESS PREDICTION Solid temperature results obtained with AVL FIRE® serve as input for Finite Element Analysis of thermal loads and deformations. A simple GUI-based mapping step is performed to produce input data for Finite Element Analyses. Finally, predicted residual stress levels are compared with operational loads. If residual stresses superimpose the operational loads, the thermal treatment is to be changed. A different submerging direction or quenchant temperature may completely change the nature of residual stresses in critical areas and thereby improve the quality and safety of components in operation. Needless to say, this extends the lifetime of the product and reduces the risk and warranty costs of OEMs in the market. Von Mises stresses during quenching simulated by AVL FIRE®; five seconds after submerging Von Mises stresses during quenching simulated by AVL FIRE®; 30 seconds after submerging Cylinder head deforming in FEA simulations utilizing AVL FIRE® quenching results as input
Solutionskatalog2016_EN
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