Welded sheets are made by butt connecting of the base plates in various welding methods. These sheets are called tailor welded blanks, welded sheets (TWBs). Due to their many benefits, they have found many uses in various parts of the industry. In this Research, the formability and effect of weld line of TWBs of St12 and St14 in thicknesses of 1 mm and 1.5 mm in single point incremental forming in the form of a truncated pyramid has been investigated. At first, the maximum depth that can be shaped in single point incremental forming of a truncated pyramid from each of the base plates for different values of wall angle was obtained and the critical wall angle for each of them was determined. Then, the incremental forming of the truncated pyramid was done using welded sheets at the critical wall angle of the base plates. In this regard, TWBs were considered with different layouts and combinations of base plates. To investigate the effect of weld line on forming depth, each combination was prepared in two weld directions of 0 and 45⁰ relative to the rolling direction. The experiment results showed that the fracture depth of TWBs with 45⁰ was reduced by an average of 14% compared to TWBs in the rolling direction. Furthermore, the average depth of the TWBs at the average critical wall angle of the base plates decreases to about 25% compared to the base plates. Therefore, the TWBs should be formed at their critical wall angles.