LASER WELDING OF HIGH-ALLOYED CORROSION-RESISTANT AUSTENITE CLASS STEEL 12Kh18N10T

Abstract

The purpose of this work is to study the effect of changing the technological parameters of laser welding of thin-walled butt joints of highly alloyed heat-resistant corrosion-resistant steel of the austenitic class 12Kh18N10T on the geometry, structure and properties of welded joints. The technology and equipment for laser welding of thin-walled stainless steel pipes for the production of multilayer bellows, which conduct or divide liquid or gaseous media, including aggressive ones, have been developed. According to the traditional technology, the bellows was made by argon arc welding of a thin-walled pipe from one sheet with a thickness of 0.5...2.0 mm, followed by hydroforming. According to the developed technology, the bellows consists of several thin-walled tubes (from 3 to 10 layers) each 0.2 mm thick, welded by laser radiation. In this multilayer design of the bellows, even if one of the welded joints turns out to be defective or fails during operation, the bellows itself will still be functional. The analysis of the results of technological research and mechanical tests showed that the connections of thin-sheet highly alloyed high-alloy heat-resistant corrosion-resistant steel of the austenitic class 12Kh18N10T, which meet the technical requirements, have maximum strength in the case of welding with laser radiation with a power of 45...70 W at a speed of 10...18 mm/s and using gas protection of the weld pool area and cooling weld metal on both sides of the welded joint. The optimal range of linear welding energy is within 4...6 J/mm. Thanks to the use of a multilayer structure welded by laser radiation, the number of defects has been reduced from 50% in argon-arc welding to 0.5 % in laser welding. Work productivity has increased by 4 times. Cyclic strength, corrosion resistance and other characteristics of a multilayer bellows are higher than the characteristics of a single-layer bellows welded by argon-arc welding by 1.5…4.0 times (depending on the number of layers and sizes of bellows). The development was successfully implemented at two enterprises in Kyiv, namely “Armatom” LLC and “Kyiv Central Design Bureau of Armature Construction”.