Rust-proof steel finish

I'm a first-time poster here, so go easy on me. I'm getting ready to fabricate some steel hardware for a timber frame home we're just
breaking ground on. These pieces will be machined and welded, and some will have planished surfaces achieved by careful hand work with a ball peen hammer. This hardware will mainly be used inside, but a few pieces will be on the exterior, tucked up under a 4-foot eve (i.e. they'll see condensation and occasional wind-driven rain). I'd like the hardware to have some sort of a blackish/brownish finish, while avoiding large amounts of orange rust bleeding onto the timbers. I'd like to achieve a natural-looking mottled appearance, similar to an old piece of cast iron cookwear. I'm after something more natural-looking than paint. I've achieved this sort of finish in the past by coating steel with linseed oil and baking it in the oven for an hour or so. This "baked-oil" finish probably provides a bit of rust protection, but I'm not sure how it would hold up when exposed to the elements over time. Any ideas...
Rich Johnson Camano Island, WA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Parkerising (or phosphorising) is what it used to be called.
It works well on steel - and gives you a brown-black sheen - with no signs of rust. Do a search - 'parkerising + phosphate + steel'

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.