ANALYSIS OF FACTORS INFLUENCING THE QUALITY OF STEEL CRANKSHAFTS.

This paper analyzes the influence of technological and composition factors on the structure and quality of ordinary and quality steels for processing forged crankshaft. It is known that influencing factors which determine the properties of ordinary steels are the carbon content and the microstructure. Beside the predominant effects due to the carbon content and the microstructure, the properties of ordinary steels can be modified by the effects of the residual elements (in addition to carbon, manganese, silicon, sulfur and phosphorus that are always present). The properties of steel can be influenced by the presence of gas, particularly oxygen, nitrogen and hydrogen, as well as by the reaction products thereof. These secondary elements usually penetrate the steel from the used scrap, deoxidants or furnace environment. The gas content depends largely on the method used to melt, on the deoxidation and casting, so that the final properties of these steels depend largely on the method used in their preparation. Thus, the factors that condition the steel properties are primarily the carbon content and its microstructure, which is largely determined by the chemical composition and the subsequent final processing of forging or by the heat treatment operations. Secondly, these properties depend on the residual elements of the alloy, non-metallic inclusions and gas content of the steel, which in turn depends on the steelmaking method. [ABSTRACT FROM AUTHOR]