Calculation methods of develpment of welding technology of low-carbon low-alloy steels

Abstract

The application of calculation methods under the development of welding technology of low-carbon low-alloy steels is considered. The aim of paper is to develop the engineering methodology and design program of welding technology of low-carbon low-alloy steels, including the increased and high strength on the basis of presented regression equations. The estimation results of the HAZ expected structural composition for the 09Г2 steel have been analyzed according to the thermokinetic transformation diagram and calculation with the usage of regression equation for different variants of chemical composition provided by the standard. In this case, the task of determination of parameters of mode and technological methods which provide the obtaining of appropriate structure and mechanical properties of the HAZ metal. The calculation procedure of welding mode which provides the optimal structure of the welded joint has been considered using data analysis and on the example of automatic submerged-arc welding of the butt joint of 30 mm thick from the 14ХМНФДР high-strength steel. One of the most important advantages of the considered calculation method is the simplicity of its operation on the computer which simplifies and speeds the work of an engineer and increases the results accuracy. After the analysis of these results the engineer can introduce another value of the preheat temperature and therefore to choose the appropriate structure and mechanical properties of the welded joint. The application of regression equations allows taking into account the specific steel chemical composition and obtaining more trustworthy calculation result comparing to the result of thermokinetic transformation diagram. Moreover, these equations give more full information both on metal structural composition of heat-affected zone and on its mechanical properties. The calculation is easily performed on the computer which allows simplifying and speeding the work of engineer, increasing the results accuracy.