1.Metertrial:gray iron HT250/GG25=heavy truck brake drum 2.Weight:20kg-85kg 3.Chermical composition: C:3.0-3.3% Si:1.6-1.9% Mn:0.7-0.9% P:<0.12% S<0.12% 4.Mechanics performance: Main body degree of hardness:163-255HBS Testing rod tensile strength:>=220mpa ...