Are welds stronger or weaker than the parent metal?

Question

i understand you have grain growth so does this make the weld harder, more brittle and weaker?

Answer 1

The ideal weld will be stronger than the parent metal.

Answer 2

The short answer is stronger, but under the right conditions, type/method of weld, and the metal to be welded.

I have been working around welders for over 20 years and can say that rarely does a proper weld "break" before other sections of the parent metal.

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Answer 3

it depends on the settings of the machine if correct then a weld is stronger because of the penetration if its mig welds you can lose a percentage of material thickness around the edge of a weld i.e if the material is 2.00mm thick and once welded it could go down to 1.8mm so when you do a destruction test the metal will break around the edge of the weld.

Answer 4

It depends on the type of electrode you used and the net effective area of the weld. Assuming that you have a butt weld whose net area is equal to the area of a mild steel parent metal; if you use a 6011 or 6013 electrode, the tensile stength of the weld is just about the same as the parent metal. But if you used a 7018 electrode then the tensile strength of the weld which is about 70,000psi is stronger than the parent metal which has a tensile strength of about 60,000psi.

Answer 5

It depends on what metals you're welding and what you're welding with.

If it's steel and steel, it depends on the rate of cooling.  If it cools quickly the grain can't form in the weld and it will be brittle.  If it's allowed to cool slowly there's more chance of a malleable grain developing.

That's why steel tubes that require hard joins are braised, brass forms a much harder and less brittle bond than steel weld.

In aluminium, you don't get that grain so it's irrelevant.

Answer 6

Metal welds can be designed to be stronger or weaker than the parent metal according to the application they are used in.

The grain growth depends on the temperature that the weld reaches, and the rate of cooling. Faster cooling produces smaller grains and slower cooling produces larger grains.

The actual size and shape of the grains depends upon the chemical composition of the metal IE the percentage of carbon and other minerals that can be added via the flux used in the weld process.