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Chuck Stewart
08-08-2010, 11:13 PM
I'm finally getting my outdoor fireplace after pouring the pad two years ago and failing to commit to the project, but I've found a mason and we are off the ground and building. My main requirement was that I have a large firebox, I've seen so many that have this huge structure with this tiny firebox, so we built it 32" long by 32" deep and he stepped out the bricks to put a cooking grate. Now I'm on a mad search to find a grate that is that long and coming up with nothing but eye strain. I've looked at the custom built ones and boy are they nice, you can even have a logo put in them but I'd rather not take a second mortgage on the house to buy one. I guess a two piece would be ok,say 32x16. Come to think of it I better run a board through there to make sure it's square, may be better off with 31 1/2 inches. Anyway, If anyone knows where I could locate something like this it would be appreciated. Hate to bother my welding buddy but will as a last resort. I was kind of looking for cast iron anyway and I've heard stainless is a pain to weld. I'll send pictures when it's completed, 26 hours and still rocking

harry strasil
08-09-2010, 2:26 PM
Stainles is not hard to weld, it can even be welded with regular rods, altho that part will rust, the bad part is the cost of SS. You might check a used commercial kitchen supply for some kind of grate or oven grate that can be modified easily. Also check bbq grill grates.

FWIW, Cast Iron breaks easily, and rusts terribley.

Steven DeMars
08-09-2010, 3:48 PM
The best way to go in my opinion would be a CNC Plasma cut grill out of a piece of 3/8" or 1/2" plate. Stainless or carbon would work.

A grate that was only 32"x32" overall would not cost much for the material or the cutting.

If you have someone local that does CNC Plasma cutting it should be no problem.

I have drawn these for several smaller grills for people. You could even incorporate your favorite team LOGO into the grill or family name . . .

Where are you located?

Steve:)

Cliff Rohrabacher
08-09-2010, 4:05 PM
If your grill gets really hot, Stainless is going to rust anyway.
Heating SST up past 800F (I think it's 800F) will cause the chrome to migrate away from the surface leaving the surface depleted, the heat will also strip away the chrome oxide passive layer and food acids will finish the job.

After welding the only ways to get it passivated again are ether to do a solution soak where you heat it to critical and quench it in 70F water (I think it's 70F) or just grind a little metal away in the area of the weld where you see discoloration fro the heat of welding.

You might try a super chrome metal instead of the usual 304 maybe try 316? but still you will be heating it and dousing it with food acids.

The best metal, bar none, if you want corrosion free performance is Inconel.

Steven DeMars
08-09-2010, 4:09 PM
Here is an example . . This grate would weigh 110 lbs if made with 3/8" plate.

A flat plate grill is a lot easier to clean and keep looking new than one made with welded rods.

Plus in stainless it won't rust. You can always make it look new again with a orbital gander and some green pads.

Steve

Take advantage of the technology that exist today . . .

Steven DeMars
08-09-2010, 6:15 PM
The best metal, bar none, if you want corrosion free performance is Inconel.

That would be one VERY high dollar grill . . . :)

Steve

Cliff Rohrabacher
08-09-2010, 10:28 PM
That would be one VERY high dollar grill . . . :)

Steve

Yes it would. Inco alloys are tough to work and not common enough to be cheap. But they are superb for high temp high corrosion applications

harry strasil
08-09-2010, 10:55 PM
"If your grill gets really hot, Stainless is going to rust anyway."

Good Stainless is Non-Magnetic and won't rust!

Steven DeMars
08-09-2010, 11:52 PM
"Good Stainless is Non-Magnetic and won't rust!

Thank you . . . I did not be the one to open that can of worms . . .:D

And yes you are correct, low carbon stainless will not rust unless contaminated by grinders that were previously used on carbon steel . . .

Steve

Cliff Rohrabacher
08-10-2010, 1:23 PM
"If your grill gets really hot, Stainless is going to rust anyway."

Good Stainless is Non-Magnetic and won't rust!

Oh no Harry. That's a mistake lots of folks make.
I am unsure what you mean by "good stainless." There are grades with varying amounts of chrome in them ( denoted by the numbers like 300, 304, 316 etc.). Stainless comes in three main flavors (1) austenitic, (2) ferritic, and (3) martensitic.

Austenitic SST has, on average, 12 - 20 % chromium with as much as 35% nickel these are the most corrosion resistant.
Some austentic SST has added carbon to make it heat treatable (400 series)
Then there are way of smelting it which makes it more or less workable and imparts different characteristics, ( like double vacuum smelting which knife forgers love) and there are alloys which can make stainless better or worse for certain applications.

But as to rust:
You can rust Stainless a bunch of ways.
1.) apply to it, muriatic acid or chlorine or other acid or caustic that strips the chromium away.
2.) abrade it with plain ferritic steel or iron
3.) Weld it to or using ferittic steel expendables
4.) heat it to it's critical and let it cool slowly which causees the chrome to migrate away from the surface.


The reason Stainless does not rust is solely because of the Chromium in it. You need about 12% chromium for the metal to precipitate a passive chrome oxide layer on the surface.

But Harry, I just know you are not the sort to just swallow things wholesale without question, so here is some material for you to puruse if you please.
Care and cleaning
http://www.ssina.com/view_a_file/cleaning.pdf


Lots of varied info:
http://www.ssina.com/faq/index.html

Heat treating such as after welding:
http://www.azom.com/details.asp?articleid=1141
more:
http://www.azom.com/Details.asp?ArticleID=965

Main page with search options for azom:
http://www.azom.com/

About Welding it

http://www.gowelding.com/met/austenitic.html



Stress Relieving

After welding 304L or 316L Stainless Steel, you need to heat treat in an anneal. During welding Chromium carbides precipitate at the grain boundaries of the heated metal.
In carbide form the chrome can’t form the passive chrome oxide layer leading to corrosion (rust) at your weld joints. Annealing allows the carbides to be absorbed back into solution.

You can do a minimal anneal at around 400C.

Baking at 425 to 925C significantly improves the metal condition eliminating stresses that might lead to corrosion or stress. One hour at 870C typically relieves about 85% of the residual stresses.

To accomplish a full anneal the metal is heated to 1080C and cooled rapidly in a 70C water bath.

However, stress relieving in this temperature range can also precipitate grain boundary carbides, resulting in sensitisation that severely impairs corrosion resistance in many media. To avoid these effects, it is strongly recommended that a stabilised stainless steel (grade 321 or 347) or an extra-low-carbon type (304L or 316L) be used, particularly when lengthy stress relieving is required.

Full solution treatment (annealing), generally by heating to about 1080C followed by rapid cooling, removes all residual stresses, but is not a practical treatment for most large or complex fabrications.

Low Temperature Stress Relieving

When austenitic stainless steels have been cold worked to develop high strength, low temperature stress relieving will increase the proportional limit and yield strength (particularly compressive yield strength). This is a common practice for austenitic stainless steel spring wire. A two hour treatment at 345 to 400C is normally used; temperatures up to 425C may be used if resistance to intergranular corrosion is not required for the application. Higher temperatures will reduce strength and sensitise the metal, and generally are not used for stress relieving cold worked products.

harry strasil
08-10-2010, 1:42 PM
Thanks for the Info, but my days of working with SS are over after 55+ years, I worked mostly with food grade SS, from a meat processing Co, heat resistant SS, making shields, conveyors and such for a large Striking Tool Mfging plant. and tanks, piping and other assorted machinery used in the commercial Fertilizer Industry and feeding equipment used in large Swine Confinement buildings. I never had any problems with any of the work I did for any of the above other than the detailed cleanup on Food Grade SS work. The one govt inspector at the Meat Co I was told was very hard to get along with and no one could please him with their work. I had no problems at all with him and as he had to sign off on everything I did for the plant, if he knew that I had done the work, he would sign off on it and not even inspect it. I am just an old country blacksmith, but my standards were higher than the ones he used. All of the SS was furnished by the companies except for the Swing operations and I specified the material for use in it. My only specifics were that it be non magnetic, as the usual SS that was used by the big companies was stainless clad, and after a couple of months of licking the equipment, the hogs licked thru the clad material and it rusted.

Joe Chritz
08-10-2010, 2:11 PM
We use a large piece of some kind of expanded metal for a grate on an ancient pig roaster we use several times a year.

We also use a stainless metal pan that was put together by someone working at a commercial kitchen manufacturing place.

There will be no live bacteria on that grate within a few seconds of starting the grill. Besides roast 100 pounds of pig one time and it shouldn't rust for about a 1000 years. Pig fat is amazing stuff.

Joe

Chuck Stewart
08-13-2010, 4:24 PM
Steven, I'll take a look at the PDF when I get home, at work right now and they have a strict policy of not downloading anything on their computers. Not sure if just opening it is downloading but I will wait anyway. Been busy stoning this thing and have not had a chance to get online. 34 hours into it and figure one more good day next week should finish it. The mason has been working around my goofy work schedule and yesterday we got a good 7 hours in even though the temp here in Ottawa Illinois got up to 105 degrees. Had to change my shirt midday because it was soaked, what was I thinking doing this in August? My mason is 74 years old and retired and says "what" "is it hot out here, I never noticed". I'm reaching the limit of my budget so yeah, cheap is good, though seriously, what's the rush now anyway, this thing definitely aint going nowhere. Guess I got excited when the brick started going up.Now I'm looking at chain saws, log splitters and anything to do with fireplaces. My wife is giving me the eye that says back down big dog.