Controlled cooling of drop forged microalloyed-steel automotive crankshaft

Abstract

Certain aspects of determination of continuous cooling conditions directly after forging and their applicability to industrial conditions are discussed. On example of high-pressure-pump crankshaft problems concerning realization of drop forging of microalloyed-steel forged shaft with thermomechanical treatment involving subsequent direct controlled cooling are presented. The paper is focused on determination of both forging conditions and subsequent cooling parameters, which in combination with modelling of precipitation kinetics in the analysed steel allowed accomplishment of required final mechanical properties of the forged part. For the determined conditions of thermomechanical treatment experimental trials in industrial conditions were carried out. Obtained in simulation pattern of continuous cooling was realized with a line consisting of six stages of controlled rate of stirred air flow. Satisfactory level of mechanical properties, exceeding minimum of the assumed requirements was reported, as well as uniform fine grained microstructure regardless of cross-sectional dimensions, meeting the requirements of automotive industry.