the quality/size of welding has a significant effect on the metal performance. poor welding might induce minor cracking which can trigger tensile fracture.

The tensile strength could increase in the as-welded condition (assuming the composition of weld and base metal is similar) because the weld metal in as quenched condition will have a high concentration of point defects (vacancies) and high dislocation density.

The lower strength (than base metal) could be due to unwanted phases and microstructures, segregation, or macro defects in the weld.

Dear @Hothifa Rojob and @Krishnan Raja

Thank you very much for your valuable comments.

I understood form the comments that the quality of weldment is the affected factor on increasing or decreasing the tensile strength after welding process.

In case of getting values of tensile strength (yield or ultimate) lower than the base metal value, is there any value of tensile strength can be considered as accepted welding process such as if we get the value of yield tensile strength is about 90% of the yield tensile strength of base metal?

Thanks in advance.

For acceptable values of mechanical properties of the welds you have to refer to the standards (such as AWS or ASME section IX etc.) or specifications by the customers.

Dear Mr.Raheem,

Warm greetings to you. The increase or decrease in tensile properties of the welded joints may be due to any one or more of the following reasons:

1) Type of welding; 2) Type of base metal; 3)Temperature at which the process takes place; 4) Cooling if used; 5) Phase transformation; 6)Nature of Intermetallic compounds formed; 6) Defects in the welded region; 7) wrong selection of electrodes if used; 8) Improper selection of process parameters and 9) sometimes, the thickness of the material welded.

Have a nice day.

Thanks (@Narasimhalu Ethiraj) for your valuable information

Résiduelle Stress