How to make 304 stainless un-rusty....

[HoleshotHolset]

Calling all metalurgists (sp?) !!



How would one make 304 stainless NOT rust??!! (I'm assuming that it's 304... . those are the only #'s that make sense amonst all of the numbers printed on the backside of these things... )



I have a few objects bolted to my truck that are rusted... . mostly at the welds and wherever the steel brake bent the stainless.....



I'm hoping that the 80-grit on the electric sander did the trick... but I read somewhere that I have to put some kind of acid on the welds to keep it from doing this... . Or what kind of polish/wax/magic fairy dust to put on these things.....

A mirror finish would be nice, but I kinda like the brushed look that I have goin' on right now... . I just want it to stay like it is and not get that annoying surface rust that just wipes off... .



BTW, they're bumpers... . and I'm not particularly pleased with them. Sloppy work... almost looks like the guy got frustrated with working with the stainless and said: "Ship 'em to that #@%& guy up there in Massachusetts... . I don't ever want to see these again!!"



In all fairness..... I won't disclose who I bought them from until I get the issue resolved. It might not be his fault, etc... .



Thanks in advance,





Matt



BTW, what is THE recommended type of drill to use with stainless? I've had good luck with cobalt and titanium... . but I want to know which is better..... Thankfully, I have a dril sharpener... I would have NEVER been able to even put these on the truck without it... .

 

[jlccc]

Originally posted by HoleshotHolset

Calling all metalurgists (sp?) !!



How would one make 304 stainless NOT rust??!! (I'm assuming that it's 304... . those are the only #'s that make sense amonst all of the numbers printed on the backside of these things... )



I have a few objects bolted to my truck that are rusted... . mostly at the welds and wherever the steel brake bent the stainless.....

IIRC, that's one of the reasons that 304L was invented. It's low-carbon. I can't remember the exact term (decarburization?) but when metal is heated to high enough temperatures to weld it, the carbon atoms congregate just outside the weld zone. It changes the chemical property of the stainless steel in those areas and allows it to rust.



I'm not sure why rusting would occur at the places where the tubing was only bent though.

 

[Straight6Jeff]

quality

Matt, The stainless you have will continue to rust unless you protect it with a coating. Even at that, it's a band-aid. The 304 does not contain (much) molbdenum which gives other grades (such as 316ss) it's superior corrosion resistance. From the looks of your welds, the guy did not back-gas the area (as evident by the "crystal" look on the back sides). I would talk to the guy to see if He'll make right, or you might have to have the thing painted or powder coated.



The stainless tow hooks on the Ruenel bumper are 304 and have been rusting since new. I have had them electro polished, passivated, and they still rust.



Good luck

 

[paccool]

Matt,



If they used a regular wire brush on the welds to clean them up, that is what is probably causing the rust. Getting some iron precepitation from particles left in the stainless. We use 304 stainless steel screws all the time putting down a fiberglass sheet on cooling towers and the square hardened drivers used will cause the same problem. Had a customer that wanted me to replace all the screws once until I pulled some out and showed him it was just around the top where the drivers had been used.



Make sure you use a brass or stainless steel brush if you try to clean up these areas.



The welds also need to be heat treated to prevent corrosion (rust) from forming. We see this all the time but discoloration is not a real issue in a cooling tower.

 

[Sled Puller]

My Luverne STAINLESS steps are rusting.



I complained, said hey, if i wanted rust, I would not have bought stainless.





They said try WD-40.



Thanks Luverne.

 

[LSMITH]

Gene. just be glad you did not buy a Luverne stainless brushguard, it is a rustbucket at only 3 1/2 years. On the other hand my Luverne stainless step bars have not rusted at all.....



If you want to end the rust on 304SS have it chromed. Plate with nickle then chrome. It will cost a small fortune though.



Tips for drilling SS : low rpm and hard feed, split point drills will break the corners off if fed hard enough to make them cut well, Use a small drill and progressively open the hole up again with low RPM and hard feeds, if you let the drill rev up and the chipload drop you will dull the drill in short order. TiN coated drills work the best in SS after carbide, moly coated work well but the moly wears off quickly. Try a drill with a 113* point after poking the initial small hole with a 118* drill. If you have a sharpener and this is a one time type of thing get the cheap hardare store drills and hammer away. Drilling SS by hand can eat up a lot of $$$$$ in drill bits in a hurry. If you have a drill with some serious power a two flute uni-bit works quite well for opening holes up as long as you keep the RPM low. Hope this helps.

 

[HoleshotHolset]

Thanks for the words of wisdom on the bumpers..... I think I may call him to see what can be done.



Many thanks for the info on drilling too... . I'm saving all this info for future reference.



After sanding the ever living crap out of 'em with an electric sander... . the rear is holding up very well. Pretty much everywhere that I spent a boatload of time sanding down has survived this weekend's latest round of rain/*SNOW* we've had here in north central, Mass. The welds on the rear bumper have a LOT less rust on them than last time..... and overall looks 1/2 way decent.



The front is rusting on the vertical sides, and the bars... . just that annoying surface stuff. The horizontal surfaces seem unaffected... .



Gene is right... . if i wanted rust, I would have bought regular old steel. I was naive in thinking that a BUMPER MANUFACTURER would use a low grade stainless on something that would be subjected to all kinds of things.



I'm almost thinking of sandblasting the heck out of 'em..... sanding seems to help out a lot... . so 'blasting them might work too... . any thoughts??



Explain this "heat treating" process to me..... I have oxy-acetylene!



BTW, I paid 75% more than the cost of regular steel for these things... . JUST BECAUSE I DIDN'T WANT THEM TO EVER RUST!! #@$%!



Matt

 

[Rammin On]

Matt ...



This might sound strange ... . but it works ..... toilet bowl cleaner will dissolve the rust right off of the stainless ... . use a toothbrush to get the stubborn spots.



Keith

 

[ZEEEW]

I think I remember reading how the chromium oxide that forms on stainless after it is made is what keeps it from rusting.

Once the surface is scratched, the metal can rust, even though it is stainless. Where the bends are would cause the coating to flake off, also allowing rust. I would guess that sandblasting would make the problem worse.

 

[THerman]

Stainless steel does NOT mean RUSTPROOF! No matter what number... 304, 316, etc. And as Straight6Jeff states, Heat will draw the carbon to the surface...



This is corrected by pickling and passivation. Under normal conditions stainless steel will self "repassivate" but once scratched, heated, bent at a sharp radius, the passivation in undone.



But the 304 is not as resistant to water and specifically salt water as is 316. But it is MUCH easier to machine and work and is somewhat stronger as well.



People don't think of aluminum as rusting, but it will oxidize as well. Protective coatings or chrome is about the only way to protect something you hang on the front of your truck!

 

[HoleshotHolset]

I guess I should have started this thread BEFORE I bought the $#&* things.....



Oh well... .



Thanks for the added info... . I'm gonna try that toilet bowl cleaner trick... . anything is worth a shot at this point.



It just kills me that only small portions of them are rusting... .



Anyone have a good commonly found anti-rust potion? I was thinking a weekly or biweekly application of WD-40 might help... . but I'm no rust expert... all I know is that I HATE IT!



Matt

 

[Rotty]

Stainless steel, If it contains iron (FE) in the mix of the metal, it WILL rust. period. There are many different type of stainless steel, some do not have iron, others contain lots of iron. I am by no means an expert, but when you have family that works in the metalurigical (sp) business, you learn things. Stainless steel is a big name misnomer.

A good example is the stainless hardware (screws, etc)in home depot and true marine stainless hardware that cost 10 times more. See which rusts first in an marine enviroment.

As always, remain informed, and know what you are buying.

"cavet emptor".

And if I get flamed, so be it.

I have been burned in the past myself by stainless ... ...

 

[M Barnett]

I have worked in stainless and have had the best luck with cobalt drills. Comparing to drilling regular steel, less spindle rpms and more feed. Its important to not let the drill sit and rub the stainless without cutting, it will workharden quickly.

Michael

 

[HoleshotHolset]

Aaaaahhh, so that's what was happening with the hand drill..... before I switched to laying a decent sized Delta drill press on the floor next to the bumper... . I was using a 1/2" 800rpm hand drill. "Workhardening"... . that's exactly what was happening. I'd burn the crap out of a nice cobalt (and even a really nice titanium bit... . ) and then that hole would become literally undrillable... until I used the drill press. I even tried to heat the area I was drilling to a nice cherry red... . that didn't do didly squat.....



With the Delta set to 250rpm, a good sharp cobalt drill, about . 25 quarts of transmission fluid (ghetto cutting oil... ) and a boatload of pressure... it cut and made those nice twirly shavings like crazy.



I really appreciate all of the kind words and "I told 'ya so's"..... just goes to show what I know about metals... . and what pretty much the entire general public knows.



I propose a name change for stainless steel..... it should be called "stain resistant steel".



You live, you learn... . hopefully you don't make the same mistakes twice... . but if you do, it isn't the end of the world.



Mat

 

[Bill Lins]

Mebbe it should be called "drill-resistant" steel.

 

[HoleshotHolset]

When people type "LOL"... . they are usually laughing on the inside... . but when I say that I was "Laughing Out Loud"... . this time I really meant it!



It's "drill-impossible steel"..... #@$%!



Matt - King of Quotation Marks

 

[M Barnett]

HoleshotHolset: It is actualy pretty easy to machine when you get the right tooling {cobalt} combined with speed and feed. But like you mention, let the drill bit spin without cutting and it hardens quickly. To harden carbon steel, heat and quinch. With stainless if you heat and let it come down to room temp gradualy, it will harden unlike carbon steel. If you have any more trouble, bring that bumper over, my plasma cutter just loves stainless steel.

Michael

 

[HoleshotHolset]

Yeah, I'll make the short drive to AZ next time I need a hole cut... . hehe



I'm almost positive that's how the dude cut it all up before welding... . plasma cutters are NICE! They simply demolish aluminum... . Not that I'd know from 1st hand experience...



So, how do you soften "Drill-Impossible Steel"?



Matt - still waiting for 304 grade stainless anti-oxidation magic fairy dust.....



BTW, what's the verdict on the WD-40 or other sprays? Think it'll work?

 

[HoleshotHolset]

Well, after almost a year and LOTS of grinding/polishing and swearing the stainless parts don't look 1/2 bad.



I imagine that taking them to have them professionally polished would cure the oxidation problem for good.



The one section that I spent the most time on, and also has the smoothest finish - is the section with NO oxidation whatsoever.



Matt

 

[RBrunson]

Holes

Matt, I think a couple well placed rounds from a . 44 Mag would do nicely