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Mixed Steels Treatment - Coatings


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Hi All,

I have a Part steel bit welded up to a stainless (low grade - 304 ?) tube, and I was thinking of the fact it will rust, so to protect it some way. I popped into see my tame Passivator - but he says "non" to mixed steel / stainless able to be done.

What else could I do, and am I right that paint (if it comes to it) doesn't like to stick to stainless - if so whats the method of painting ?

Otherwise is there another treatment other than passivation I could try to find out about ?

Nige

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what would happen if you used some of the galvafroid type galvanising paints on it?

not sure about painting stainless - all the stainless bits on my outboard that I can think of are all bare and I think the painted bits are all aluminium so maybe it doesn't stick :unsure:

the only stainless thing I can think of on the boat that is coated is the VHF aerial and that is plastic coated which probably wouldn't be hellish effective on an exhaust pipe :lol:

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Hi All,

I have a Part steel bit welded up to a stainless (low grade - 304 ?) tube, and I was thinking of the fact it will rust, so to protect it some way. I popped into see my tame Passivator - but he says "non" to mixed steel / stainless able to be done.

What else could I do, and am I right that paint (if it comes to it) doesn't like to stick to stainless - if so whats the method of painting ?

Otherwise is there another treatment other than passivation I could try to find out about ?

Nige

Very difficult to weld carbon steel to stainless steel, use a magnet to determine what you have. 304 (austenitic) not exactly low grade stainless (non-magnetic), not at the prices currently being charged. More likely that you have carbon steel welded to martensitic stainless (magnetic stainless) in the form of Cromweld 3CR12 or 1.4003.

In either case your only option is powder coating / painting.

A lot of sign manufacturers use stainless where a painted sign is needed but you do need to use etch primer. Usefull when the paint is chipped that the material will not rust. Austenitic stainless with etch prime exceptionally good for painting.

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We weld non magnetic stainless to mild steel all the time with very good results. In fact, it welds lovelly. I've seen a discovery with full stainless inner wings and sills welded to the mild steel floor. I've also mig welded with mild steel wire commercial dishwashers made from 316.

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We weld non magnetic stainless to mild steel all the time with very good results. In fact, it welds lovelly. I've seen a discovery with full stainless inner wings and sills welded to the mild steel floor. I've also mig welded with mild steel wire commercial dishwashers made from 316.

Well you surprise me!

I can laser weld dissimilar materials and have welded carbon steel to stainless 304 full depth keyhole welds, but with mig and steel wire?

:D

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Well you surprise me!

I can laser weld dissimilar materials and have welded carbon steel to stainless 304 full depth keyhole welds, but with mig and steel wire?

:D

I can confirm it is a poor quality stainless (304 - 316 is the "Good stuff ?",

and Mild 'FON' Grade Steel (F Orrible Nasty Grade :) )

I know cos I made begging and pleading noises to Tonk down the phone till he gave up,

he said the language from the welder was "Choice" :)

Being 304 and Mild mix is going to rust fast and nasty,

could paint (spray tin) but think even '304' is 'not good' to get it to stick to - hence me thoughts on passivation,

and that seems out :angry:

Galv will leave a mess as its thin wall (VERY thin wall :lol:) and powder coating seems OTT and bling

Is the etch the same as ali as I have some of that ?

Nige

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I think most acid etch is just that - a mild acid. Even Halfrauds sell it now (red tins) and it will eat into most things and provide a key.

Zinc Phosphate primer sticks to SS too because there are a few bits of stainless in the 109 (must be low-grade 'cos it's welded to mild nicely :huh: ) and they're painted with it.

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