REVIEW OF EXISTING METHODS OF WELDED JOINTS’ STRENGTH INCREASING

Abstract

In the work the analysis of scientific and technical information of existing methods of welding production for increasing the strength of welded joints is performed. Effective ways to increase the strength of welded joints are listed. Among these processes should be attributed mechanical, thermal, thermomechanical and ultrasonic processing and icreasing of the wel-ding joints’ strength by using of wires with different composition. The advantages and disadvantades of the listed methods are mentioned. The reasons for destruction of welding joints are analyzed. It was established that the main attention is paid to increase of the strength of welded joints and structures, which work under variable loads, to deternination of the processing method, which increases the material yield strength and eliminates the concentrators during design. The possibility of thermomechanical treatment is established, it is expedient to use a loop or rolling of a weld seam, heated to 850…950 o C for this purpose. The efficiency of ultrasonic processing increases with increasing of the steel’s strength, provided that the same loosening regimes are used. It is established that one of the reasons of joint’s destruction is the non-uniform distribution of stresses in two, the strength of the welded joints can be increased by mechanical, thermal, thermomechanical and ultrasonic processing. One of the steps to remove welding stresses is to melt the transition area from the seam to the base metal. Melting a small amount of base metal and metal seam leads to a reduction of stresses by 60…70%. The resulting smooth transition from the seam to the base metal contributes to a significant increase in the welded joints’ strength in variable loads. The significant disadvantage of the method is the need for a complicated technological cycle of the manufacture of the weld metal construction, which necessarily leads to the increasing of its manufacturing cost. Therefore, there is an urgent need to find and implement such methods for increasing the strength of welded joints, which would not lead to a significant increasing of the process’ technological cost.