Din 1.4104 Stainless Steel, in a Marine Environment?

[Ian_Edwards]

Any metallurgist out there who can advise on whether DIN 1.41404 Stainless Steel is suitable for use in an above water marine environment (i.e. could get soaked with salt water but not continually immersed)?

It seems to be a high chromium steel which can be heat treated to harden it. I goggled it and came up with the following composition.

C	0.12
Mn	1.25
Si	1.00
Cr	16.0-18.0
P	0.06
S	0.15 (min)
Mo(optional)	0.6

What I really want to know is whether it will produce rust stains like A2 (304) does.

 

[macd]

This site suggests it's not heat-treatable (as if you'd bother), machines relatively easily, but doesn't weld well and has 'moderate' strength and corrosion resistance:
http://www.suppliersonline.com/propertypages/430f.asp

No doubt Vyv will be along in due course with something more learned.

 

[TimBennet]

I believe it's a ferritic, machinable, high sulphur, 400 series (430F ?) stainless steel.

The addition of sulphur to aid it's machine-ability lowers its resistance to corrosion. It's also not possible to polish it which is often the best way to reduce rust streaks.

It will also be magnetic like mild steel.

It's certainly not a common or standard marine grade.

 

[cliff]

Although 1.4104, contains 17 % chromium, the corrosion resistance of this steel is severely compromised by the addition of sulphur. This is particularly true when exposed to environments that promote pitting and crevice corrosion.
Corrosion resistance of this steel is considerably lower than the AISI 300 series (worse than 302 / A2) ans should be avoided in any marine application.

 

[Ian_Edwards]

Thanks for the replies I'll avoid it then.

 

[vyv_cox]

Cliff beat me to it. We have had other things to spend our time on in the past 12 hours - strong winds from two directions a couple of hours apart, thunder and lightning, torrential rain and half the Sahara desert deposited on deck. Greece in summer!

The alloy is a 400 series not containing nickel. Something like it has been used by Jeanneau for prop shafts, where at least in some cases it has suffered quite worrying corrosion. Several examples on the website.

 

[cliff]

Cliff beat me to it.

There is more than one Metallurgist on the forum don't you know

 

[vyv_cox]

There is more than one Metallurgist on the forum don't you know

Even if you don't count the amateur ones