To Calculation of Fillet Welds

When making welded joints, it is not always possible to press tightly elements to be joined before surfacing the weld. In normative documents on welded joints, the allowable gap between the elements to be connected can reach 3 mm  when welding with a covered electrode and 2 mm when welding in shielded gases. At the same time the presence of a gap is not taken into account in the standards for calculation of welded joints. Experimental studies have been carried out to determine effect of the gap on the bearing capacity of the weld. Specimens have been made with welded joints of two types: for work in shear and pull-out. For the purpose of comparison, half of the specimens have been made without gaps, and the other half with gaps between the elements to be joined. The specimens have been made at the Minsk plant of technological metal structures, and their tests have been carried out in a research laboratory of the Belarusian National Technical University. Based on the results of the experiments, it has been concluded that the gaps between the elements to be joined significantly reduce the bearing  capacity of  the welded joints.  In addition,  inspection of  fracture surfaces  have  shown that, in the presence of a gap, the  cut  surfaces of  the weld  pass along the  fusion boundary  of  the base and deposited metals.  It has  been  experimenttally established that the existing gap leads to a slight increase in the penetration depth. However, the latter factor does not compensate for the decrease in the bearing capacity of the welded joint due to the presence of a gap between the elements to be joined.