Evaluation of thermal stressed state in welded joint of alloy Inconel 690

Abstract

The results of evaluation of thermal stressed state in welded joint of nickel alloy Inconel 690 are presented. The experimental-calculation analysis of thermal processes and mathematical modeling of stress-strain state in single-pass welding was performed. The verification of the data by comparing the experimental thermal cycles with the calculated ones showed a good similarity of results of both as to the sizes of a weld as well as to the thermal cycles in the zones at the different distance from the fusion line. The kinetics of stress-strain state in different zones of welded joint was analyzed considering the probability of hot crack formation. It is shown that under the conditions of modeling linear one-pass welding of plates of 3 mm thickness with energy input of 304 J/mm the arising stresses and deformations do not exceed the critical values and, at the same time do not create the conditions for hot crack formation. The applied mathematical model can be used in evaluation of kinetics of stress-strain state for different variants of welding (change in energy input, different filler material, etc.). 7 Ref., 1 Table, 5 Figures. K e y w o r d s : nonconsumable-electrode arc welding, nickel alloys, thermal processes, thermal cycles, mathematical modeling, stresses, deformationsThe nickel-based alloys play an important role as corrosion-resistant materials in the nuclear and chemical industries, especially under conditions of operation at the high temperatures, considerable stresses and aggressive environments. The widely used nickel-based alloys at the present time are alloys of Ni-Cr-Fe alloying system. One of such alloys is Inconel 690 with high chromium content (30 %) [1]. The welded joints of Inconel 690 with appropriate filler materials showed a high sensitivity to hot crack formation, particularly under the conditions of welding of thick-walled structural elements. The alloys manifest the highest tendency to the formation of ductility-dip cracks [2,3].As was shown previously [4], the ductility-dip cracks in welding of alloys of alloying system Ni-Cr-Fe occur at the temperature range of 1050-650 °C, the value of critical deformation of crack formation ε cr is about 1.2 %.The thermal processes in fusion welding have a decisive influence on the nature and kinetics of changes in the stress-strain state, structure and properties of weld and HAZ. In this regard, the analysis of temperature fields in welding of alloys of Ni-Cr-Fe alloying system with the aim of further investigations of kinetics of stress-strain state and evaluation of tendency to hot crack formation is an urgent problem.The aim of the work was a comparative experimental and calculation analysis of temperature fields and modeling of stress-strain state in one-pass argon-arc welding of alloy Inconel 690.The computer prediction and calculation allow determining the temperature fields for different values of thermal power of the arc. Using the calculation procedure the efficiency coefficient of the arc is established, which varies depending on the ...