FERRITIC-PERLITICAL STEEL FOR AUTOMOTIVE ENGINE COMPONENTS WITH IMPROVED TOUGHNESS BY CALCIUM ADDITIONS AND THE MANUFACTURE METHOD THEREOF.

摘要

The present invention relates to a ferritic-pearlitic carbon medium steel for use as a feedstock in the manufacture of crankshafts, camshafts and automotive engine components with improved toughness, and the method of manufacture thereof. The composition contains expressed in % by weight, carbon: 0.38% (± 0.01), Manganese: 1.33% (± 0.02), silicon: (0.55% (± 0.02)), copper: 0.25% maximum, chromium: 0.14% (± 0.02), nickel: 0.15% maximum, sulfur: 0.050 -0.065%, aluminum: 0.03 maximum, nitrogen: 0.013 -0.017%, phosphorus: 0.02% maximum, molybdenum: 0.05% maximum, vanadium: 0.11% (± 0.01), and characterizes by containing calcium additions of 0.004% (± 0.001). The remaining percentage is formed by iron and impurities resulting from the manufacturing process. These last additions modify 45% of the MnS inclusions contained in said steel. The shape is also modified by elongated shape to a globular or round shape, thus improving the steel toughness of up 10% to 24% compared therein, without cal cium inclusions, without needing subsequent thermal treatments or vacuum casting conditions and requiring low-alloy of the elements that become scarce and vulnerable to commercial mining activity.