An experimental study of the patterns of changes in transverse displacements in the weld zone during crystallization during argon-arc welding of AD0 grade aluminum with a nonconsumable electrode was carried out. The data obtained can be used to select the optimal welding mode, safe from the point of view of crystallization cracking.
The article discusses the feasibility of using statistical methods for analyzing the accuracy, stability and control of TP, provides for process control on only one indicator of product quality. For a dimensionless quality indicator, parameter estimates are considered and numerical characteristics of these models are found. Based on the obtained estimates, a method for determining the quality of technological processes in mechanical engineering is proposed.
The results obtained indicate that when butt welding without a gap, the base distance, depending on the welding speed and preheating temperature, may decrease, increase or remain unchanged. The moment when the rapprochement of the base points begins is of greatest interest from the point of view of assessing the possibility of the formation of crystallization cracks in the weld. Conditions under which a decrease in the base distance occurs simultaneously with the crystallization of the metal in the analyzed section is safe when creating crystallization cracks, since the weakened section of the weld is subjected to compressive action from the surrounding metal, fully or partially compensates for tensile stresses, which are caused by complex shrinkage. If the base distance remains unchanged during crystallization, this indicates the presence of tensile stress, which is due to complicated shrinkage. This also creates the risk of crystallization cracks, since stresses are usually concentrated in the weakest axial region of the weld, where the metal hardens last.