AS-CAST HIGH STRENGTH NODULAR IRON WITH FAVORABLE MACHINABILITY

摘要

A nodular iron alloy and automotive components, such as crankshafts, are provided. The nodular iron alloy may include iron, about 3.3-3.9 wt % carbon, about 0.2-0.5 wt % manganese, about 1.9-2.6 wt % silicon, about 0.15-0.30 wt % copper, about 0.03-0.06 wt % magnesium, about 0-0.02 wt % sulfur, about 0-0.1 wt % chromium, about 0-0.05 wt % phosphorus, and/or about 0-0.01 wt % tin. The nodular iron alloy may include a number of graphite nodules, each having a diameter between 15 and 120 micrometers, and the graphite nodules having a number density of at least 90 per square millimeter. Iron may surround the graphite nodules in an amount of 20-40% of a ferrite microstructure and 60-80% of a pearlite microstructure. The nodular iron alloy may have an ultimate tensile strength in the range of 550 MPa to 680 MPa as-cast and at least 80% nodularity.