It depends on materials to be welded, thickness of work-pieces, configuration of joints, welding technology, etc. Chemical composition, structure, and stresses are the main factors which influence on strenght. It may be higher than base metal. For example, see 'Katayama S (ed) (2013) Handbook of laser welding technologies. Woodhead Publishing Limited, Cambridge', Chapter about laser welding of titanium alloys. We have the same results for pulsed laser welding of Zr-1%Nb alloy (the manuscript is peer-reviewed now).

For our laser welded joints of Zr-1%Nb there are no relationships between hardness and strength

dear Mikhail Slobodyan

i am welding a shaft and yoke in steering assembly

• material is steel
• co2 mig welding is used
• weld bead thickness 5.274 mm
• electrode used is ER70s-6

the hardness value decrease in sequence

weld zone---->HAZ(heat affected zone)-------->base metal

then what will be strength effect here ?

hope you understand my problem!

regards

Surendran.R

As I know, the main problem of this technology is the fact that CO2 is an active gas.

Carbon dioxide dissociates in the arc: 2CO2 → 2CO + O2.

Oxygen reacts with the molten metal in the weld pool with the formation of iron oxide: 2Fe + O2 = 2FeO. Oxidation of the metal affects the mechanical properties (first of all, its plasticity).

Deoxidizing elements which interact well with oxygen are added in welding consumable to prevent this process.

In you case it is welding wire alloying with manganese and silicon. However, despite this, the ductility of welds are lower than, for example SMAW, MIG or SAW.

Therefore MAG (not-MIG) welding is not recommended using for structures operating at low temperatures, with shock loads, and other critical conditions.

I hope this information will be useful for you. In other case please ask a more specific question.

Best regards

thank you very much it is so useful for me

Mikhail Slobodyan