S.G. Iron Castings

SG Iron Casting

SG iron is a type of graphite-rich cast iron discovered in 1943 by Keith Millis. While most varieties of cast iron are weak in tension and brittle, ductile iron has much more impact and fatigue resistance, due to its nodular graphite inclusions. SG iron is used in many grand piano harps (the iron plates to which high-tension piano strings are attached).