This paper describes the behavior of GMAW welding process with metal cored wire, in welding unions of ASTM A131 grade AH 32 steel using two shielding gas compositions and methods of transfer in short circuit and pulsed arc. The mechanical properties and microstructure were evaluated and the results indicate that is obtained greater tensile strength and a more uniform hardness profile using the pulsed arc transfer mode. Likewise, the porosity in the foot of welding of joint in T with deposit in fillet are related by arc length.