... steel,stainless steel.brass,aluminum,brass.cooper. carbon steel. 2.Surface:zinc plating ,powdered,pas Torsion Bar Spring 1.Material:steel,stainless steel ... .brass,aluminum,brass.cooper. carbon steel. 2.Surface:zinc plating ,powdered ... lines1) The lost-wax casting of stainless steel and heat-resisting steel with silica-gel shell made of mid ...