Tensile Stength of Welding Materials

Not my field of expertise...but I can't think why you could possibly want it weaker.
Del

Welds often are in higher stress areas. There is a chance of inclusions or less than optimal conditions. Surface irregularities are often greater if a weld is not ground smooth.

For these reasons, it makes sense that the tensile strength of the filler material should be greater that of the workpiece.

I gave you a GA.

I used to work a lot of trade shows at my previous job. I watched a guy doing a sales pitch on a 3-in-1 filler rod for aluminum. He would use a hammer and nail to punch a hole in the bottom of a soda can. Then he would heat the area around the hole with a small propane torch and flow this miracle rod into it like solder. Then he would try to drive the nail through the repaired area and would end up smashing the can. What most people missed during the demonstration was how much extra filler he was using. The wall thickness of the repair was well over 1/8". No way in heck the nail was going to puncture the can before the sides collapsed.

That is a very good explanation Abdel. Del had it too when he pointed out that it would be silly to use weaker weld metal than base metal. It is surprising to me how many people think that the weld is weakest part of a piece. When you factor in the that welding is only as good as the welders skills it is really very easy to see how someone could think this. It doesn't take much of a problem to make a weld the weak point even though the metal has a higher tensile. A weldment from higher tensile material is also usually thicker than the base metal due to reinforcement in the cap and/or root pass will be stronger than the base metal if welded correctly. Take the same weld and introduce undercut in the root pass, lack of fusion, trapped slag or a host of other problems will make it the weak point. This "human error" is why we have the safety factors that we figure into most designs IMO.

Dear The Mechanic thank you very much for your good observation.

Dear pipewelder, Very good explanation showing why the weld -in most cases- is stronger than the base metal itself.

Very good answer. A further consideration would be that dilution of the filler material can be as high as 45% into the base material, making for a better transition. You don't want to build in a weak point. Many years of weld inspection has shown me that properly laid weldments fail in the HAZ (heat affected zone). Improper weldments fail raggedly through the weldment and the HAZ.

I believe that the weld material is always considered stronger than the base material.

From what i remember from college and working on weldment on submarines is that if the weld is a good weld when you try and rip apart say two plates welded down the middle the failure always occurs in the base material and not the weld.

Brian