The flight is the most strained element of a screw. That is why murex offers you highly effective hard-facings against wear and corrosion.
Several types of hard-facings are available:
|Hard-facing||Base alloy||Hardness||Thickness||Flight width||embeded|
|Stellite 6||Cobalt||HRC 38–42||2.0mm–2.5mm||min. 2mm||yes / no|
|Stellite 12||Cobalt||HRC 43–49||2.0mm–2.5mm||min. 5mm||yes / no|
|Colmonoy 56||Nickel||HRC 52–56||2.0mm–2.5mm||min. 5mm||yes / no|
|Tungsten carbide||Nickel||HRC 56–60||1.0mm–2.0mm||min. 6mm||yes|
|Hard-facing||Stellite 6||Stellite 12/1||Colmonoy 56||Tungsten carbide|
Attention: the chosen hard-facing has to be compatible with the barrel material!
To apply the hard-facings we use a state-of-the-art CNC operated PTA-welding machine. Our welding process ensures durable and robust hard-facings. Due to our CNC operated welding machine the quality is always at the same high level.
Detailed information on our hard-facings
The structure of the Stellite 6 hard-facing consists on an austenitic matrix on cobalt basis with embeded Cr-W-carbides. Stellite 6 is a good compromise between tenacity and hardness. It is suitable for all applications, especially if a low number of cracks in the hard-facing is more important than wear protection.
The structure of the Stellite 12 hard-facing is similar to Stellite 6 (austenitic matrix on cobalt basis with embeded Cr-W carbides). The amount of carbid builders (Cr/W) is higher than the one in Stellite 6, therefore Stellite 12 is harder and offers a better wear protection. Stellite 12 is the standard wear protection.
The Colmonoy 56 hard-facing consists of an austenitic Matrix on nickel basis with embeded chromium borides, which are extremely hard. Colmonoy 56 does not only offer a better wear resistance than Stellite 6 and 12, but also a very good protection against corrosion, since it contains nickel instead of cobalt as basic material.
The structure of our Tungsten Carbide hard-facing consists of an austenitic matrix on nickel basis, with up to 60% tungsten carbides embeded. This is the best available hard-facing. It has outstanding properties concerning wear protection as well as corrosion protection. Because of the very high hardness of this hard-facing, it is impossible to achieve a crack-free surface.
For all kind of hard-facings it has to be taken into account, that tension cracks in the surface may occur. The harder the hard-facing, the higher is the number of cracks. But these cracks are a normal phenomenon which do not have any negative influence on the quality and lifetime of your screw.
Please do not hesitate to contact us in case of any questions concerning these cracks. We will be glad to support you in finding the optimum hard-facing for your specific application.