Casting manufacturing of cylindrical preforms made of low alloy steels

Abstract

The manufacturing of complex drivetrain components made of steel requires multi-stage manufacturing processes, resulting in long processing times and high costs. Forged parts get their final geometry after multi-stage forming operations. One approach to shorten such process chains is close contour casting of steel preforms and a single subsequent forming step to achieve high strength properties similar to those of multi-stage forged parts. Since the application of precision forging using cast steel preforms has been studied insufficiently up to now, the manufacturing of cylindrical preforms made of the low-alloy heat-treatable steel G42CrMo4 by sand casting was investigated. Using casting simulations, suitable casting parameters for the finished casting systems were identified and nearly pore-free preforms were achieved. Depending on the casting system, metallographic investigations revealed different fractions of bainite in the microstructure of the casted preforms. Subsequently, the cylinders were deformed in upsetting experiments by which the remaining porosity could be eliminated. The numerical casting simulation was combined with a forming simulation to model the reduction in porosity and to allow the prediction of the densification behavior in further research employing more complex geometries.