HT250 is the grade of gray cast iron, HT stands for gray cast iron, HT is the abbreviation of gray cast iron Chinese pinyin, and gray cast iron HT250 represents the minimum tensile strength of 30 samples 250MPa
Carbon c: 316～3.30 Si Si: 179～1.93 manganese mn: 089～1.04 sulfur s: 0094～0.125 phosphorus p: 0120～0.170 mechanical properties tensile strength rm (mpa): 250 hardness :(rh=1) 209 hb specimen size: test rod diameter: 30mm
The strength [2], wear resistance, heat resistance are good, the vibration damping is good, and the casting performance is excellent, so artificial aging treatment is required. It can be used for pump casings, containers, towers, flanges, packing box bodies and glands, carbonization towers, nitrification towers, etc., which require high strength and certain corrosion resistance; Machine beds, columns, cylinders, gears and parts that need to be surface hardened can also be manufactured. Because of its small amount of thermal deformation, it is often used in high-temperature occasions. Heat treatment specification: (determined by the supplier, the following is the heat treatment specification of a sample, for reference) as-cast metallographic structure: flake graphite + pearlite HT250 quenching can reach HRC60, but gray cast iron (HT200, HT250, etc.) is generally used in the annealed or normalized state, without quenching treatment. If hardness is required locally, high and medium frequency quenching can be carried out. Medium frequency quenching: hardened layer 3 5 mm, hardness HRC50, less deformation of the workpiece. High-frequency quenching: hardened layer 1 2 mm, quenching temperature 850, surface hardness HRC50 or more; The quenching temperature is 900 1000 degrees, and the surface hardness can reach HRC60. 