Roller in High Cr+ ZTA Ceramic + GGG composite centrifugal
The characteristics of High chromium cast iron + ZTA ceramic roller by centrifugal casting.
Detail:
Roller in High Cr+ ZTA Ceramic + GGG composite centrifugal
The characteristics of High chromium cast iron + ZTA ceramic roller by centrifugal casting.
1. Using bi-metal composite centrifugal casting technology.
2. The centrifugal casting without pores and inclusions by using centrifugal force.
3. Fast cooling metal mold making the casting have a compact microstructure to improve wear resistance.
4. Using high chromium cast iron(Cr17NiMo,Cr18Ni2,etc)+ZTA ceramic to the out layer of roller, using alloy ductile iron like GGG400 etc or alloy steel like 35CrNiMo etc at inner layer (with high strength and toughness).
5. By reasonable wear resistant layer thickness design according to client’s requirement to reduce the dosage of alloy and the cost.
The production process.
1. Smelting.
The molten steel (P and S with content of ≤0.02%)for the outside layer add various kinds of alloy for mixed melting, making bath analysis to certified composition, together with deoxidization protection in the process f melting.
2. Casting pouring
According to the roller size and weight to choose the appropriate centrifuges. Cast moulds choose grey cast iron or cast steel material, spraying a certain thickness of refractory coating. To control the cleanness inside the mold strictly, inclusion-free, to ensure the quality of castings. Roller shell use layered casting: outer layer, transition layer and inner layer, pouring according to the process setting in advance. The outer select proper pouring temperature, after interval of time, pouring the transition layer, to ensure that the outer layer and transition layer have a good composite state, after a interval time again, pouring the inner layer. Stay all inner and outer molten steel pouring out, waiting for the roller demoulding after coagulation casting, after demoulding, adopt the annealing process.
3. Heat treatment
The roller use annealing, quenching and tempering heat treatment process. After demoulding, the roller casting will directly be put into the heat-treatment furnace for annealing, after that, take rough machining, and then quenching, several times with tempering process to eliminate the internal stress of castings thoroughly.
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