This paper is aimed at studying the tensile behavior of duplex stainless steel weldments. A set of experimental tests was conducted in order to investigate the influence of a certain number of variables, referred herein as to behavioral parameters [arc current, arc voltage, welding speed and heat input (HI)]], on the strength of duplex weldments. Using an experimental design technique a combination of this behavioural parameter was chosen in order to investigate the influence of each individual parameter.

Test specimens were welded using a GMAW process and were divided into two groups. In the first group, the weld bead was maintained, therefore the specimens were reinforced (Figure 1a). For the latter group the weld bead was machined, therefore they were unreinforced (Figure 1b).

Figure 1. Geometry of specimens:

Figure 2 shows a comparison between the yield strength (S_0.2) and the ultimate strength (S_u) for the weldments and for the base metal (S_0.2bm, S_u bm). It seems that the strength increases slightly with the welding speed while maintaining the arc voltage constant

Figure 2. S_0,2 and S_u vs. HI for the specimens with reinforcement.

Figure 3 shows the influence of heat input on the strain at ultimate strength level (e_u) of the weldments for an arc voltage constant. In this figure, it is also represented the strain at ultimate strength of the base metal (e_ubm) and it is shown the welding speed decreases the weldments strain also decreases for all the established conditions.

Figure 2. e_u at S_u vs. HI for the specimens with reinforcement

Additional empirical expressions are presented herein as a function on heat input and the distance between the weld bead to the fracture location, and ultimate strain (e_u). The experimental results were rather similar for the two groups of specimens.