Quenching and tempering heat treatment to ductile iron could increase the surface hardness of castings, to make the casting with good hardness and abrasive resistance.

The normal quenching and tempering treatment could increase the surface hardness to about HRC 29 to HRC 42 of Rockwell Hardness, this process includes the heat heated to 870-935 centigrade, then quenching in the oil, then do the tempering treatment in 486-610 centigrade. From our Dandong casting factory experience, this quenching and tempering treatment  process could get high hardness, improve the mechanical properties, and abrasive performance.

If we need more higher surface hardness HRC 49 to HRC 54,we have to use carburizing furnace to

Finish the process,the hardness depth  can from 1 mm to 2 mm,it is up our customers request.

However, some problems found in our production process came from customers.In order to increase the surface hardness of some customers,we

take the quenching and tempering heat treatment for some blank casting parts,after them receive these parts to finish the finial machining,they  found that their machining center couldn't machining process for  these parts,these parts surface roughness too higher so that very difficult to machining.So it is why

we need to control the hardness within a reasonable range.