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View Full Version : Material Differance 304 to 303?



madman
07-05-2007, 12:05 PM
If someone wants 304 material would they even know if it was 303?? I wonder what the differanc ewould be? Also i dont think there would be any negative effects using 303 instead of 304. The application is for liquids water and even possibly milk inside stainless type vessels i am going to be constructing. Im already scared to machine 304 sounds purely evil... (thats form reading the previous posts regarding that material. Any tips on machining large holes in 5 inch stainless 304 tubing would be appreciated. Mike

DR
07-05-2007, 12:18 PM
If the container will have food grade products in it, don't even think about substituting materials from the customer's original spec.

Also, 303 is not weldable.

316 is more corrosion resistant than 304, and IMO it machines easier.

Whatever SS you use, don't forget to have it passivated after building, otherwise it'll develop rust streaks which look bad.

ERBenoit
07-05-2007, 12:36 PM
Without knowing for fact which is which I highly doubt anyone would be able to offhand tell the difference. I can't. 303 machines a bit easier than 304, but, you would need a chemical analysis to accurately determine one from the other. 304 work hardens easlily, especially well when taking light cuts and a slow feed. The tool needs to feed faster than the work hardening is advancing. In other words, an agressive feed is necessary.

If what you are doing is going to be in contact with food stuffs, FDA materials within compliance fitting your application may be necessary or at least desired.

Not that the Machinery's Handbook is law, under typical applications, 202 actually lists as uses in kitchen equipment and milk handling.

A.K. Boomer
07-06-2007, 09:24 AM
What a difference one little number makes, as far as common materials 304 is about the nastiest stuff going to machine, I mean nasty like dont even think about pulling out swarf from your lathe without leather gloves and then be careful, It can get unbelievably razor sharp, I believe it has quite a bit more nickel in it than 303, I also know 303 is much more brittle, 304 is maleable, I built hollow rivets that i could utilize a 60 degree punch to fan out the ends and they just split wide open with the 303 but the 304 expanded with no prob. and worked perfectly, The metals have a slightly different color when compaired side to side, 303, 304, and 416 are about the most common materials that my friend uses in his machine shop, He can tell what they are just by dragging a file across any of them...

MCS
07-06-2007, 03:28 PM
"Stainless steel type 1.4305 is popularly known as grade 303 stainless steel. Grade 303 is the most readily machineable of all the austenitic grades of stainless steel.

The machineable nature of grade 303 is due to the presence of Sulphur in the steel composition. Whilst the Sulphur improves machining, it also causes a decrease in the corrosion resistance and a slight lowering of the toughness. The corrosion resistance of type 303 is lower than that for 304. The toughness is still excellent as with other austenitic grades."

One of the first links on google for "stainless 303".

303 is ideal for automated machining. I remember that hex bars were 303.
Machines much easier than 304.

tattoomike68
07-06-2007, 04:00 PM
I used to build wire EDM tool holding fixtures from 304 1" X 4" flat bar, it had a tough skin that was work hardend from rolling.

Milling it was a pain, I had to crank the feeds, surface grinding it was a nightmare as it was not magnetic and it would grow with heat big time so a tiny pass would be a monster grinding pass on a part that is not stuck to the chuck. .0002 was a big grinding pass.

Tapping it was a nightmare, I had to oversize the tap drill a bunch in order to keep taps from breaking. I used roll taps as they were stronger.

If I never use 304 for anything again I will be happy with that.

Go with 316 if you can.

madman
07-06-2007, 06:01 PM
Well i ordered $1000 dollars worth of the crap today. In Monday the Nightmare begins. I need some more tips on sawing use coolant ?? Loads of coolant??

lazlo
07-06-2007, 06:54 PM
303 machines a bit easier than 304, but, you would need a chemical analysis to accurately determine one from the other.
304 work hardens easlily, especially well when taking light cuts and a slow feed.

303 is a special-purpose free-machining stainless intended for screw machines. Like 12L14, they add sulfur to make it more machinable, but that also lowers its corrosion resistance, and makes it very hard to weld.

304 (18-8) is the most commonly used stainless steel. It's a totally different animal than 303. It's a pain in the butt to machine -- it work hardens if you look at it wrong. But 304 is highly corrosion resistant, and welds very nicely.

I grab 303 stainless steel drops off Ebay -- almost always seen in rounds and hex. Machines almost as easy as mild steel, but rust resistant.

timcasbolt
07-06-2007, 07:02 PM
Without knowing for fact which is which I highly doubt anyone would be able to offhand tell the difference. I can't.

I can. Just stick it in the machine and take a face pass on it. Anyone with more than 6 months on the job will know something's wrong. 303 cuts like butter compared to 304. We recently had two instances of the vendor sending 304 instead of 303. The younger guys couldn't figure out what was going on with the tools burning up all of a sudden. The older guys could tell by the smell that they got ahold of the wrong material. Also, take a 1/4" bar of 303 and bend it in the tightest U you can by hand and look at the arc. Then do it with 304. 303 will crack, 304 will fold over on itself without cracking. We run a lot of 304 on Davenports at work and I hate the stuff. Can't cut it, can't drill it, can't thread it, can't knurl it. But it does make a mean flare.

fishfrnzy
07-07-2007, 03:42 AM
Madman,

One place I used to work we sold a lot of 304 ss tube and provided a lot of it cut to length. You are using thin wall I believe? If so make sure you get the right blade, feed ( a slow feed as I remember) and yes to the coolant. Also make sure you have it clamped down tight so it cannot move or spin, it will clean the teeth off a blade quickly.

FYI with regards to the 303 and 304 the cemistries are similar ecept for the sulfur added to the 303. I was told it acts like dirt to break the chips in short pieces, helps with the heat and the sulfur adds a little lubrication to the process. Also the reason they dont make tube from 303 is the sulfur (dirt) does not allow the metal to be streched to seamless or rolled thin to make sheets to make welded tube. The sulfur really is a lot of largish non- metalic inclusions delibratly put in the alloy.

By the way I have seen some nice examples of welded 303. It was done with tig but the poeple doing it wouldn't divulge how.

good luck.

A.K. Boomer
07-07-2007, 09:12 AM
FYI with regards to the 303 and 304 the cemistries are similar ecept for the sulfur added to the 303. .




I do know that my friend has stated that one of the reasons 304 behaves like it does is because it has allot of nickel in it, I believe he was making this in comparison to 303, so I dont believe that its just the sulfer - its the actual metal mix also, But because this is in no way my expertise im just quoting and may have my wires crossed, im sure someone out there has a jorgensen (sp?) book and can tell us both to set the record straight....

ERBenoit
07-09-2007, 09:45 AM
I can. Just stick it in the machine and take a face pass on it. Anyone with more than 6 months on the job will know something's wrong. 303 cuts like butter compared to 304.

Apparently my original statemenet of: "Without knowing for fact which is which I highly doubt anyone would be able to offhand tell the difference. I can't.", does not apply to everybody.

I based my statement on the fact that I do very little with stainless steel, if I make 50 parts per year from any combination of grades of stainless that is a lot. The everyday uses of stainless, based on machinining characeristics, they have an advantage. My everyday materials are aluminum and plastics.

Not being sarcastic nor attempting to start a pi**ing match, I have more than six months machining background. 20 years. What stainless I do work with is mostly 304. Some 316, 410, and 416. Sharp tools, coolant/lubricant and appropraite DOC's and feeds, I have had very little trouble machining bar or plate 304.

On four devices I had built, I did have a hell of a time machining some parts made from .060" 304. sheet. I believe that because it was worked down to sheet form, it was work hardened significantly before I had started.

ERBenoit
07-09-2007, 10:06 AM
I do know that my friend has stated that one of the reasons 304 behaves like it does is because it has allot of nickel in it, I believe he was making this in comparison to 303, so I dont believe that its just the sulfer - its the actual metal mix also, But because this is in no way my expertise im just quoting and may have my wires crossed, im sure someone out there has a jorgensen (sp?) book and can tell us both to set the record straight....

No expertise here either. Typical compositions of standard 304 and 304 Stainless Steels, from Machinery's Handbook, in percentages:

AISI 303: 17-19 Chromium, 8-10 Nickel, 0.15 Carbon, 2.0 Manganese, 1.0 Silicon, 0.20 Phosphorus, 0.015 Sulfur (minimum) 0.60 Molybdenum (optional)

AISI 304: 18-20 Chromium, 8-10.5 Nickel, 0.08 Carbon, 2.0 Manganese, 0.75 Silicon, 0.045 Phosphorus, 0.030 Sulfur, 0.10 Nitrogen

Little more of this, little less of that, some of this, none of that.

How any of this translates to machinabilty of 303 vs. 304, that I do not know.

jkilroy
07-09-2007, 10:42 AM
If you are working stainless do youself a favor and drop that 304 right where it belongs, in the crapper. Then pony up for some 316. 303 is a dream to cut compared to 304. You can't *****foot around with 304, when it is time to cut, CUT. Otherwise it will work-harden so damn fast, and so much that you can kiss that piece goodbye.