By whpraml
Date 05-13-2007 21:31
Edited 06-01-2007 15:21
Please recommend the type/grade of steel to use to replace the baffle of my wood stove.
Steel Requirements:
Resistant to oxidation
Resistant to heat (Highest interior temperature not known. Highest exterior stove temperature 400C/800F.)
Resistant to warping (creep)
Weldability
Baffle dimensions (approx): 12" x 5" x ΒΌ"
The baffle located at the top rear interior of the wood stove (adjacent to the flue opening) has deteriorated due to oxidation. The baffle takes the brunt of the heat due to its location. The stove otherwise is in good condition. (The original baffle held up for nearly twenty years.)
A welder replaced the baffle three years ago; however, because the wrong type of steel was used, the baffle again needs to be replaced due to oxidation. The baffle showed significant deterioration after only one heating season, although the welder did a good job fabricating the replacement.
I've been told that steel will rapidly oxidize if it contains a high carbon content (i.e., carbon will readily burn out of steel under conditions of high oxidation such as from burning wood). The wood stove manufacturer has not been able to provide a recommendation.
Since steel is not my area of expertise, I would appreciate your help. Would plate ferritic 446 be a good choice?
The manufacture would have been the place to start, but like most, I'm sure they won't give you the exact type of steel used.
We have repaired wood stoves in the past, and here are some things to keep in mind:
1. Clean and prep the steel as much as possible to remove any soot/ carbon build up. This is really important if you're welding in any type of stainless steel.
2. Remove the stove from the home or where ever it's at if at all possible. A spark in the flue can cause a fire if it lands on some built up creosol
3. Most inside stoves are made from carbon steel plate.
4. If you're welding in some ferritic SS, we always use 409 plate with 409 metal core wire.
5. USE CAUTION!!
Replaced mine with 1/2" A 516 Grade 70 about 15 years ago and a UT test on it at several locations came in at .475-.480 (after power brushing). The baffle is lasting longer than the refractory bricks that I have to replace again.
First of all if you want resistance against oxidation you should use stainless steel, Also you need high temperature creep resistant steel you should use Molibden alloyed steel. Carbon is needed at high temperature applications in order to keep mechanical values high. To prevent bad effects of Carbon you should use prefer Niobium(Colombium) in it. Carbon oxidizes but there are oxidizing agents in your steel such as Si. If you have enough amount of Si you won't have the problem of burning carbon. This is austenitic type of steel you wont have weldability problem in this steel. I can advise the following compositioned steel:
% C : Max 0.12 Standard type : SAE/AISI/ASTM
% Cr : 17.0-20.0
% Ni : 11.0-14.0 Order name : 316 (Cb)
% Mo : 2.0-3.0
% Nb : 0.70-1.0
% Mn : 2.0-3.0
% Si : Max 1.0
% P : Max 0.04
% S : Max 0.03
% Cu : Max 0.75
Rest Fe
You can order in this composition steel you wont have any kind of problem.
