Steel surface treatments 1

[woodyrod]

Hello,

Done a search for surface treatment options, but not found anything. We are making rifle actions, and need a surface treatment for the bolt body. So far, hard chrome plating has been used, but there are a few small design changes that make the HCP less desirable now - such as easier chip points etc.

What are the choices for a treatment / plating that is hard wearing (the substrate is 52RC anyway - high alloy tool steel), and more to the point, stops the part from rusting due to lots of handling from the user.

Are there any options that can be done in our own workshop? Such as a kit of some sort, or proprietry product or process we can use?

Thanks

 

[unclesyd]

Need more information.

How is the fastener used/reused?

What type environment?

Why didn't the chrome plating work out?

 

[woodyrod]

Fastener? unclesyd, it is a rifle action, the main parts in question here being the action body - 187mm long x 38mm diameter, 22mm bore, and bolt that fits into the body.

The bolt is the part in question - usually hard chrome plated due to many cycles to lock the action in place - many thousands in the life of the action. The main issue is the bolt is handled a lot by people using the rifle action, ending up as a rusted bolt if the person is not meticulous with cleaning and maintenance (most of us probably).

Chrome plating adds cost, is a PITA due to our location (a long way from platers), and the fact we cant do it ourselves, environment is outdoors, possible rain, salt air (near the ocean), possible lack of surface lubrication by inattentive users (not in our control).

Also, the chrome plating has been known to chip off on smaller sharp corners, and from imperfect handling from users (there is a theme here).

 

[Compositepro]

A black oxide finish is a possibility. I've seen ads for processes that can be set-up in a small shop. I have not used it myself.

 

[unclesyd]

Damn, another senior moment.

All the following can be accomplished on a small scale with a nominal investment.

Here is one strong candidate, Parkerizing, for your "bolt". It's a phosphating process that's been around for years and works quite well. Depending on your requirements you might want to go to someone like Brownells or if the requirements are high go to Henkel.

http://en.wikipedia.org/wiki/Parkerizing

Here are some of the Black Oxides eluded to by Compositepro.

I've used products from all three with good results. The higher temperature products generally give a much better coating.

http://www.heatbath.com/heatbath/products/black_oxide_finishing/black_oxide_for_ferrous_metals

http://www.birchwoodcasey.com/trutemp/index.html

http://www.epi.com/black-oxide/hot-oxide-blackening.html

 

[woodyrod]

Thanks for the help, I will contact the people mentioned and see what happens. I will try to post what happens.

 

[dgallup]

Black oxide is nowhere near the durability & corrosion protection of hard chrome plate. I have not personally used Parkerizing, but I don't think it is up to this task either. I think it will wear through pretty fast. There are a ton of very hard & corrosion resistant surface treatments like DLC, TiN, etc. but most of them will not be something you can do yourself.

Have you considered a high chrome content tool steel like D2? It is almost "stainless". What about 440C? 17% Chrome & you can harden it to ~60 HRc.

 

[MintJulep]

Something like a Teflon impregnated nickel might be useful.

Give someone like Nimet or General Magnaplate a call.

 

[woodyrod]

dgallup,

The steel has been chosen by the designer for its particular suitability to this task, and that it has very little distortion after heat treatment. It also has a high content of nickel and chrome, so is not far from SS itself.

There is only about 0.004" play between the bolt and body, so there is not much room for distortion. I personally do not like multiple machine operations like turning, heat treatment, grinding, plating - just too difficult where we are located due to lack of services here, and long distances and timeframes.

Looks like we might have to give the surface treatment a miss and go with the 52RC material surface, being polished.

 

[israelkk]

Did you considered using PH stainless alloys such as Custom 455, 465? for the bolt body. They have excellent dimension stability and the desired hardness. However, they may cost more.

 

[GRoberts]

I'm not sure of its suitability, but I have seen kits for hard nickel plating, or the Boron nitride EN kit.

http://www.caswellplating.com/kits/bnen.html

 

[Maui]

Woodyrod, I suggest that you give this company a call to discuss your problem - they will likely be able to help you:

http://www.ultimatecc.com.au/products.htm

Maui

 

[EdStainless]

One reason that black oxide works is that it is hard, durable, and slightly porous. The result is that oil (with good corrosion inhibitors) tends to be retained. As long as the parts are cleaned and oiled occasionally they will survive.

Personally I like the idea of electroless Ni plating. You will want to select a plating base on adhesion.

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Plymouth Tube

 

[11echo]

Alittle late, but what about a traditional color case hardening? I've dealt with a number of vintage firearms that had this type of treatment/finish and it's lasted a number of years.