UPGRADING SHELL TUBE HEAT EXCHANGER’S “TUBE-TUBE PLATE” UNIT’S CONSTRUCTION 15Cr5Mo STEEL

摘要

The technology of 15Cr5Mo steel “tube-tube plate” unit’s arc welding, that is used nowadays, includes some difficulties like the necessity to perform preheating to 300…350 °С, accompanying heating during welding and post-welding heat treatment, that is heating to 700…750 °С and exposure at this temperature during 2 or 3 hours with slow cooling. Obviously that production of this unit requires significant costs, therefore raises the question of considering the using alternative welding technologies.This issue presents comparison of mechanical properties and microstructure of 15Cr5Mo steel welding joints samples, made with the using of two welding technologies – arc welding, that is widely used nowadays, and friction welding, that using is limited today according to absence of specified equipment and constructive solutions. At the same time friction welding has a wide variety of positive qualities: high performance and energy efficiency, the ease of automation, and high and stable quality of welding joints. The process of friction welding could be performed on programmable machines with low use of manual labor or even without it. The results obtained for static bending, corrosion resistance and led to conclusion of purposefulness of using friction welding instead of arc welding heat exchanger’s “tube-tube plate” units, because friction welding allows to obtain welding joints with the same level of mechanical properties, as arc welding, without the use energy-intensive heat treatment operations. That fact allows reducing material and energy cost, as well as to enhance to the quality and speed of production.