Development of a High Strength Isothermally Heat-Treated Nodular Iron Road Wheel Arm

摘要

This report describes the redesign, material characterization, material selection, manufacture, and testing of a proposed road wheel arm for the M-1 tank. The material selected is bainitic ductile iron (BDI). This material, made by the casting process and heat-treatment, takes advantage of the toughness of bainite (acicular ferrite), the ability of the casting process to make a complex shape, and a 10 percent lighter than steel weight. A further advantage is its relatively low cost compared to a steel forging. A set of 14 road wheel arms were made and assembled. Dynamic tests on the design passed the 650,000 cycle specification, going beyond one million cycles. A 35 pound or 27 percent weight savings per arm was achieved, and based on figures obtained during the project, a considerable cost reduction can be effected.