Structure of welded joints of 14MoV6-3 and 13CrMo4-5 steel elements after design work time under creep conditions

Purpose: This paper is to present changes in the structure of material of 14MoV6-3 and 13CrMo4-5 alloyed steel components of power station boiler after long-term creep service. Design/methodology/approach: The investigated materials were obtained from Polish power stations. All the examined elements have exceeded their assessed life of 100 000 hours. The structural investigations were carried out on materials after long-term service under creep conditions. The microstructure was observed using light and scanning electron microscope. The investigations on the development of precipitation processes were done by X-ray diffraction phase analysis. Findings: Carbide precipitation evolution in correlation to the life exhaustion extent was presented. Practical implications: The presented methods can be used for evaluation of materials working under creep conditions. Originality/value: The presented results on changes in the structure and precipitation processes are applied to evaluation of the condition of elements in further industrial service.