Best metals for high heat applications ???

JPigg55

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I have a corn/pellet stove (USSC model 6100) that the agitator for the burn pot needs repaired/replaced.
Here's a link to an eBay listing for one with picture: https://www.ebay.com/itm/STAINLESS-...182912?hash=item41d9658380:g:mH8AAOSwGvhUFKSY

The issue is the welds for the fingers have been failing and a couple have fallen off.
My options (as I see it) are to:
1. Try and weld new finger on old agitator.
2. Buy a new one (USSC want over $90, hence the eBay listing).
3. Make one.
Making one seems the best and cheapest option as I can make it out of a single piece of metal negating the welds.
Problem is I'm not sure what metals would work best for this application due to the heat and corrosive environment. The original and replacements are made from some type of stainless steel rod probably 1/2" dia (haven't measured).
Given the cost of a chunk of SS big enough to machine it from as a single piece wouldn't be cheap or even that easy to machine on my small lathe, buying one may be the better option.
Any advice on a cheaper metal that would work ???
 
You can't buy much SS for $39, but if you did want to do it yourself, I'd use 316 SS
 
Use round bar and stick weld with 316l rods, should last you a while.
 
If your going to make it yourself use 316L SS shd 40 pipe and weld with 316l rod. The pipe will have less tendency to warp with heat. Before you weld heat the welding rod to 150F in a toaster oven welds much easier and less spatter. All that being said maybe just spend the $39.00
 
I suggested something I have relevant experience of, I've fabricated BBQ grilles and grates in 316 and they hold up well.
I know cracking in weldments is a common issue with Iconel so which alloy and what rods for the part the OP enquired about?
Welding procedure with any Pre/Post heat requirements?
DON'T Google it! ;-)
 
I have a corn/pellet stove (USSC model 6100) that the agitator for the burn pot needs repaired/replaced.

If you are having a problem with welds, I would consider redesigning the part. Make the central bar square and bore holes to accept accept a necked down finger. Make the neck long enough to protrude through the opposite end of the bar and peen the end to hold in place. It should last a lifetime.

If oxidation isn't an issue, you could use mild steel. Otherwise stainless. I had to replace the cast iron agitators on my 80 year old wood burning furnace and used wrought iron. They lasted until I replaced the furnace ten years later. Wrought iron has a higher melting pont and is more resistant to burning out.
Agitator.JPG
 
I suggested something I have relevant experience of, I've fabricated BBQ grilles and grates in 316 and they hold up well.
I know cracking in weldments is a common issue with Iconel so which alloy and what rods for the part the OP enquired about?
Welding procedure with any Pre/Post heat requirements?
DON'T Google it! ;-)
My experience with inconel machining are parts for induction furnaces, difficult to machine at best. Have welded it once using GTAW with inconel filler, the weld will sometimes crack before you are finished. Gut instinct suggested preheat then slow cooling but this I have not tried, if I am fortunate I will never have to weld it again.

The customer supplied the material without a specific alloy call out, just Inconel.
 
If you are having a problem with welds, I would consider redesigning the part. Make the central bar square and bore holes to accept accept a necked down finger. Make the neck long enough to protrude through the opposite end of the bar and peen the end to hold in place. It should last a lifetime.

If oxidation isn't an issue, you could use mild steel. Otherwise stainless. I had to replace the cast iron agitators on my 80 year old wood burning furnace and used wrought iron. They lasted until I replaced the furnace ten years later. Wrought iron has a higher melting pont and is more resistant to burning out.
View attachment 257501
If I made the replacement, I was planning on a different design.
My biggest concern is with warping. Binding will cause the gearbox motor to fail and they aren't cheap either.
I thought about using cast iron, have some old farm equipment I could scavenge the metal from.
I priced stainless and came to the conclusion I'd be ahead to just buy a replacement. The only way to make it as cheap or cheaper would be to make it much like it is with 1/2" rod and weld the fingers on. I've never welded stainless steel, but have a neighbor who's a retired welder that could.
 
Best alloy for this is 310 stainless. Significantly cheaper than Inco 600 or 601 or some of the refractory metals, and it's easy to weld with matching filler.

Also a vast improvement over 316 at resisting high-temp oxidation up to about 2000F. Call Atlantic Stainless or Penn Stainless. Both list 1/2" round bar in stock.

An alternative is 309 - good up to 1500F. McMaster has it in 1/2" rod for $36 per 2' section.
 
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