Case study – 0.25” (6.35 mm) carbon steel

0.25’’ (6.35mm) carbon steel (A36) butt welding in root opening, no prep

Welding Parameters


Approximate plasma/GMAW single-V welding parameters used to join 0.25″ (6.35mm) thick A36 steel plate with a 0.035″ root opening

Welding effects on the HAZ – Heat Affected Zone


Weld A36-LIN119 – Machined plate edges, as rolled mill scale on root and face sides


Weld A36-LIN113- Machined edges, all surfaces cleaned


  • Very diffused and wide HAZ was observed
  • The HAZ microstructure was very gradual from coarse at the weld side to very fine at the base plate
  • No defects were observed

Weld A36-LIN116- As rolled (no preparation)


  • This weldment without preparation had a HAZ with a coarser microstructure that the other weldments
  • The non-prepared surface did not show the appearance of defects such as porosity or discontinuities


Tensile Properties


Table 2 – tensile properties summary



Hybrid plasma\GMAW welding of  0.25’’ A36 offers the advantage of  high-quality welds, with no material prep.