Sunday, Aug 26, 2007 at 14:56
Member No 1, guess what it's not ideal to weld mild steel with stainless but it can be done.
When welding mild steel with stainless rods you lose the propertys of the stainless like corrosion resistance (it becomes diluted), you can over come this by treating welded areas after welding to obtain some of the properties or the other way to do it right is to weld a layer of Hi-Chrome-Nickelthe (309 something something from memory) this acts as a barrier and helps to keep the properties of the stainless.
You may see after you welded and left it for a few days the stailess weld will start to rust..what is happening is the ferite or iron in the mild steel has come to the surface causing rust to appear, it doesn't mean the whole weld will rust.
If the stainless properties aren't a concern then just keep on doing what you are doing.
As a rule of thumb it pays to weld the base metal with a filler of the same properties.
I have welded cast iron on a drill press with a mig, but they say it does not work....the correct way if to pre heat and use a bronze filler rod but it's lasted the last 9 years.
I have seen alluminiun welded to mild steel.....don't ask me how they did it...I did ge told.
It all depeds if you need a penertrating weld or a adhesive weld like brazing.
To do weld correctly you have to be part chemist, part scientist, part machine and part slave.
Don't think I know it all about welding, if we have to weld something out of the norm we refer to books with stuff like pre heating, pre treatment, welding technique, and after weld treatments.
This why there are specilised welders who only do one thing and it does not mean the are good at anything else.
Next week we will tak about grain growth and carbonising....can't wait.
Regards Richard
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