Electrogalvanizing technology for ferrous steel castings
Steel Casting Manufacturer shares that cast steel electrogalvanizing, cast carbon steel with high strength and good plasticity, good casting and welding performance, poor cutting performance, can be used as rolling mill frame, bearing seat, connecting rod, box, crank and cylinder block. Steel castings are widely used in the field of mechanical manufacturing because of their excellent machining properties, the ability to die-cast complex geometrical parts, and the low cost. Steel castings usually need to be galvanized, in the plating process, hydrogen is easy to precipitate, resulting in serious hydrogen, is not conducive to the deposition of metal ions on the surface of the workpiece, coating easy peeling, need special pretreatment process.
1. Steel casting base material composition and pretreatment
Steel castings are zg270-500 steel castings, and the composition (both are mass fraction) is :0. C, 0 40%. Si, 0 50%. Mn, 0 90%. 04%P and S, 98. 16% Fe.
Steel first seepage preprocessing, and then carries on the oil removal: 5% 998 king of degreasing, theta for 50 to 55 ℃, t for 5-10 min chemical degreasing treatment and anodic current remove oil, pickling, 15% hydrochloric acid, 1.5% pickling multifunctional additives, room temperature, t for 1 ~ 2 min, presoak not washed after galvanized directly.
The formulation of potassium salt galvanized solution is as follows:
KCl 240g/L ZnCl2 50g/L boric acid 30g/L
LAN - 919 18 ml/L at room temperature
PH 5.6 ~ 5.8 J 1.0A/dm2
After 20 ~ 30min electroplating, a uniform zinc coating was formed on the surface of steel castings. Post-plating treatment: light output -- R·G135 trivalent chromium blue and white blunt.
The formula of basic zinc solution is as follows:
Caustic soda 140g/L zinc oxide 120g/L
RG -- 2005 opening agent 10ml/L RG -- 2005 brightener 2ml/L room temperature
J kappa 1.5 A/dm2 predominate
After electroplating for 30min, a uniform zinc coating was formed on the surface of steel castings. Post-plating treatment: light output -- R·G165 trivalent chrome color blunt.
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