Rule of thumb for weld strength in various metals?

[TeejT]

Hi All,

I’m curious if you have a general practical rule for estimating weld strengths in different metals.

Steel – Most of what I’ve heard says that a high quality weld is as strong as the base steel.

Aluminum – I’ve heard that quality weld strength is ~ 60% as strong as the base aluminum.

Stainless steel - ?

Titanium - ?

Thanks!

 

[drawoh]

TeejT,

In many cases, the aluminium around the weld has a yield strength of about 20% of the unwelded base material.

Any material that is heat treated or work hardened, loses strength when it is welded. Sometimes, it is practical to re-heat treat. Some times, it is not. I don't think re-work-hardening is feasible. There is no substitute for understanding metallurgy, and knowing something about the welding processes.

--
JHG

 

[JStephen]

A lot of design work involves compliance with different design standards which specify allowable weld strength, and depending on that standard, weld strength may be taken the same as or lower than base metal strength. Those standards will also specify how weld strength is determined (IE, root of fillets vs leg, etc.) So, for example, ASME code, Structural Welding Code, Aluminum Design Manual, etc.
In some cases, fatigue may enter into it to complicate the situation, also addressed in those various standards.

 

[tbuelna]

The type of welding process used is very important. Conventional fusion processes like TIG or MIG can produce good weld properties if performed carefully. Specialized fusion processes like EB or laser can give excellent weld properties. Solid state processes like friction or stir welding can produce extremely high quality welds with properties equal to the base metal.