Hard Surfacing 304 or 316 screw conv. flights

[BlueBull]

We have a screw conv. dia. 165. It has to be hard surfaced on dia. & 15 mm of face for the last 450 mm. Product conveyed is sand & pulp fibre.
Which Tunsten welding method is best for max wear & min. distortion. Technogenia product is recommended but we need the welding process.

 

[Ubbe]

After a discussion with one of my friend who is working at a company manufacturing these type of components for the pulp industry, I was given the following recommendation, in accordance to there normal practice:

They use thermal coating, but coating using plasma also possible (plasma spraying).

The deposition material they use is Tungsten Carbide.
They do only do hard surfacing using TIG on black material, never on stainless steel.

My personal recommendation would be to use plasma, due to the fact that you do get at lower Heat Input.

 

[EdStainless]

There are a number of HVOF and thermal spray techniques that would work for WC deposition on these.
I would suggest that you look at your materials of construction also. A switch to duplex stainless will give you stronger base metal and better corrosion resistance and the same or lower cost.

= = = = = = = = = = = = = = = = = = = =
Still trying to help you stop corrosion.
formerly Trent Tube, now Plymouth Tube
eblessman@plymouth.com
or edstainless@earthlink.net

 

[BlueBull]

The last 450 mm of the screw is in the dewatering zone and is subjected to high abrasion. The normal stainless steels last 2 months before wearing so it is essential that these flights are hard surfaced. The first 1,5 meters there is no problem with these materials.

 

[arunmrao]

You may consider making the last set of flights with 440 grade material. These can be hardened too and will have adequate corrosion resistance also. I make cast parts for pulp mixers in this grade of alloy.

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