Hard Coating 1

[tim120]

"Can anyone help to identify a coating or process on 304 spec stainless steel?
This is a suface hardening which is on the 3 of wearing sides of a pair of vanes bolted to spinning disc (720rpm) spreading abrasive/corrosive fertiliser.
Finish appears to be similar to that of galvanised sheet and may possibly be brushed/sprayed.Thickness is minimul but extremely hard.No extreme heat has been used.

 

[ornerynorsk]

Really hard to say from a photo. Are you sur eit's 304 SS? The coating is likely a eutectic spray (flame spray) hardcoating. There are numerous types of powders used in flame spraying, tungsten carbide being a very popular one.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[tim120]

Thank you for your reply.Yes it is 304spec SS.Why do you ask?
Also I have looked at one or two flame sprays including tungsten carbide and the finish does not look like this one.As i said this finish looks very similar to galvanise and there is slight suface rippling and it has this embedded fibre charactoristic look just like fibre glass.Which I presume is a surface reaction.
The flame sprays seem to be a mutch more even coating.
The edges are also coated and it has left a 1-2mm border all the way around the masked or untreated area.
Once again thank you for your help and if you have any more thoughts they would be welcome.
Rgds
Tim Smith

 

[ornerynorsk]

Thanks for that. What you've described doesn't sound like anything within my area of experience. Hopefully you'll get some more replies to your post. There are a ton of highly knowledgeable folks on this site.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[metengr]

You will not determine hardfacing information by surface appearance (others can guess until the cows come home). If you want definitive results in determining what surface modification method or coating was used to establish the hardness, this piece needs to be sent to a lab with instructions on identifying what is on the surface of the substrate.