Ball iron casting for valve body of water treatment system valve
Matters needing attention
(a) Strict requirements for chemical composition, the carbon silicon content of the original iron liquid is higher than that of gray cast iron, and the content of manganese, phosphorus and sulfur in ductile cast iron is reduced.
(2) The temperature of liquid iron is higher than that of gray cast iron to compensate for the loss of liquid iron temperature during spheroidization and inoculation.
(3) spheroidizing treatment, that is, adding a spheroidizing agent to the liquid iron.
(4) Adding inoculant for inoculation treatment.
(5) The flow of ductile iron is poor, the shrinkage is large, so the need for higher pouring temperature and larger pouring system size, reasonable application of riser, cold iron, the use of sequential solidification principle.
(6) Heat treatment.
① Annealing. The ferritic matrix is obtained, the plasticity and toughness are improved, the stress is eliminated and the cutting performance is improved.
② Normalizing. The pearlite matrix is obtained to improve the strength and wear resistance.
③ Tempering. The matrix structure of tempered sorbite and good comprehensive mechanical properties, such as main shaft, crankshaft, connecting rod, etc., are obtained.
④ isothermal quenching. Make the parts with complex shape and high comprehensive performance requirements obtain the matrix structure of lower bainite, as well as the comprehensive mechanical properties of high strength, high hardness, high toughness, etc., to avoid cracking during heat treatment, such as spindle, crankshaft, gear and so on.
