These gear box castings are produced in Ferralium® 255, chosen for its excellent castability alongside high mechanical strength and corrosion resistance.
Sand castings of components with complex shapes and changes of section, such as these gear box castings, demand excellent castability in the material used.
From standard stainless to Ferralium® 255
A standard stainless steel was originally chosen to meet the heavy loading and corrosive plant environment, but difficulties were experienced in producing satisfactory castings. Ferralium® 255 (UNS S32550, Alloy 255, DIN 1.4507, ASTM F61) was chosen instead. It offers much better castability, with the bonus of improved mechanical strength and much improved resistance to corrosion.
The housing, cover and yoke castings shown here weigh approximately 210lb, 67lb and 34lb respectively, and the good surface finish obtained is clearly visible.
