New Water Jet Quenching Method Cuts Stress in Steel Manufacturing
Researchers have demonstrated that controlled water jet cooling can produce harder steel parts while reducing internal stress—a major problem that causes parts to crack or fail. The finding offers manufacturers a way to improve product quality and reduce costly defects in everything from automotive components to industrial equipment.
Originaltitel: Hardening of Cylindrical Bars with Water Impinging Jet Quenching Technique
<p>Hardening of carbon steel products by austenitization and immersion in a quenching medium is a widely used heat treatment to obtain a hard and strong martensitic structure. To avoid the undesired consequences, such as residual stresses or insufficient hardening depth, the cooling rates must be accurately measured and controlled. This can be achieved using the impinging water jet quenching technique. The aim of this work is to perform hardening of four low-alloyed 70 mm cylindrical carbon steel bars, using impinging water jet quenching technique with different jet flow rates, and to analyze its effect on thermal evolution and residual stresses. The temperature evolution during quenching experiments is recorded and used as input to a comprehensive quenching model to predict phase transformations, final hardness, and residual stresses of cylindrical bars. All four quenching experiments result in a fully hardened martensitic state. Furthermore, a decrease in jets' flow rate, within a certain interval, results in different thermal histories and in lower compressive residual stresses on the surface. The results from quenching simulations show promising hardness, microstructure, and residual stress predictions that are validated by hardness measurements, optical microscopy, and residual stress analysis using X-Ray diffraction method. Four 70 mm cylindrical steel bars are martensite hardened with different water jet flow rates using impinging jet quenching technique. A finite element method (FEM) quenching model is created to simulate phase transformations and predict the resulting microstructure, hardness, and residual stresses. The model is metallurgically validated through hardness measurements, microstructure observations, and residual stress measurements using X-ray diffraction technique.image (c) 2024 WILEY-VCH GmbH</p>