Whats the best stainless for marine use?

[Drains]

Al, while you're here, stainless bolts etc come in A2, A3 and A4. A3 would appear to be 316L according to what you've put above. What grade is A4?

Chandlers generally only sell A4, most other retail outlet just sell A2. A3 is fairly uncommon.

Cheers
Si

 

[TechnicAl]

Its me, I thought it was A3, its not, its A4
http://www.bssa.org.uk/topics.php?article=1

But remember these are nuts and bolts and as such are not designed for welding. 316L is better if the component is to be welded.

 

[Drains]

Cheers. So there is no A3? I'd swear i've seen them - but that's probably my selective memory selecting made up things!

Si

 

[TechnicAl]

Cheers. So there is no A3? I'd swear i've seen them - but that's probably my selective memory selecting made up things!

Si

According to that there isnt but like you, I think there used to be. Ive always thought A3 was 316. I must have imagined it as well and I cant remember where I got the info.
Mind you I did notice that the spec had changed recently but I cant imagine that they would change the grade.

What makes it worse is that I am a member of a yacht club so I should know.

 

[Luke]

we just use A4 on the boat.

 

[Hitch]

I must say, i have only ever come across A2/A4

 

[Rail_Head]

A5 Stainless

A3 and even A5 (which is based on A4) grades exist. I work in the nuclear industry where pipe work containing real nasty stuff is sometimes spec’d as A5 (or equiv) its got additions of tantalum (I think? I’m a control eng not a mech eng) all about stabilising grain structure.

Its mainly used in ‘in cell’ applications were pipe work (once committed in cell) can’t ever be accessed again by man due to high radiation levels. A bit of interesting info - before radiation proof CCTV cameras were available the only way to look into these cells was through 6 foot thick lead glass windows – wot a strange experience that is !!!!

 

[Drains]

Here you go, I did a googly:-

A1 Chromium-nickel steels specially designed for machining. Due to the elevated content of sulphur, the steels within this grade have lower resistance to corrosion than corresponding steels with normal content of sulphur.

A2 Chromium-nickel steels most frequently used stainless steel. They are suitable for kitchen equipments and apparatus for the chemical industry. Steels within this grade are not suitable for use in non-oxidizing acid and agents with chloride content, i.e. swimming pools and sea water.

A3 Stabilized stainless steels, with properties similar to A2.

A4 Chromium-nickel acid proof steels, which are molybdenum alloyed and give a considerably better resistance to corrosion than A1, A2, A3.They are used to a great extent by the cellulose industry as this steel grade is developed for boiling sulfuric acid and is to a certain extent also suitable in an environment with chloride content. They are also frequently used by the food processing industry and by the marine industry.
A5 Stabilized acid proof steels, with properties similar toA4. In this steel grade, due to the additive content of Ti, Nb or Ta, this elements appetency with carbon are better than chromium, reduce the chance of chromium carbide to replace chromium oxide, it is available to avoid the happening of lean chromium and intergranular corrosion , induce the chromium oxide content arrive at maximum.

 

[Hitch]

I suppose with all the many many grades of SS, it seems silly to have only 2 different sorts of bolts!

 

[TechnicAl]

Here you go, I did a googly:-

A1 Chromium-nickel steels specially designed for machining. Due to the elevated content of sulphur, the steels within this grade have lower resistance to corrosion than corresponding steels with normal content of sulphur.

A2 Chromium-nickel steels most frequently used stainless steel. They are suitable for kitchen equipments and apparatus for the chemical industry. Steels within this grade are not suitable for use in non-oxidizing acid and agents with chloride content, i.e. swimming pools and sea water.

A3 Stabilized stainless steels, with properties similar to A2.

A4 Chromium-nickel acid proof steels, which are molybdenum alloyed and give a considerably better resistance to corrosion than A1, A2, A3.They are used to a great extent by the cellulose industry as this steel grade is developed for boiling sulfuric acid and is to a certain extent also suitable in an environment with chloride content. They are also frequently used by the food processing industry and by the marine industry.
A5 Stabilized acid proof steels, with properties similar toA4. In this steel grade, due to the additive content of Ti, Nb or Ta, this elements appetency with carbon are better than chromium, reduce the chance of chromium carbide to replace chromium oxide, it is available to avoid the happening of lean chromium and intergranular corrosion , induce the chromium oxide content arrive at maximum.

where did you find that?. Its similar but slightly different to the SS Assocaition info. At least we know there is an A3.

The A5 is the steel that is resistant to "weld decay" so the grade is 318 but 316L is also resistant and will give similar corrosion properties.

 

[Drains]

where did you find that?. Its similar but slightly different to the SS Assocaition info. At least we know there is an A3.

My search was "A3 grade stainless", and the text I posted came from here

Si