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The evaluation of suitability for operation of repair low-alloy steel welded joints

Dziuba-Kałuża M., Zieliński A., Jasiński A., Sroka M., Dobrzański J., Linek T.

Archives of Materials Science and Engineering

2016

Vol. 78, nr 2

78--86

Purpose: The purpose of the work was to evaluate the material condition of repair welded joints of steam pipelines with regard to their suitability for operation including determination of the time of their further safe operation. Design/methodology/approach: The following was carried out: microstructure investigations using scanning electron microscopy, investigations on mechanical properties at room and elevated temperatures, determination of the fracture appearance transition temperature based on impact tests. The abridged creep tests without measurement of elongation during test were carried out to determine the material’s residual life. Findings: The time of safe operation was determined for welded joints made in 14MoV63 steel after long-term service and 14MoV63 steel after long-term service and in the as-received condition. Practical implications: The applied methodology and the adopted procedures are used in evaluating the condition and forecasting further operation of new repair welded joints for the pressure part components of power equipment working under creep conditions. Originality/value: The obtained results of investigations will be the elements of materials characteristics worked out by the Institute for Ferrous Metallurgy for the steels and welded joints made in them to work under creep conditions.

Estimation of the residual life of L17HMF cast steel elements after long-term service

Zieliński A., Dobrzański J., Golański G.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 34, nr 2

137-144

Purpose: of this paper is to present the changes of the mechanical properties and structure in material components of the power station boiler after long-term creep service made of G17CrMoV5-10 low-alloyed cast steel. Design/methodology/approach: The material of the research studies has been obtained from Polish power stations. Examined element has exceeded their assessed life of 105.000 hours. Mechanical properties and structure examinations were carried out on material after long-term service in creep conditions. The microstructure has been observed using a light and a scanning electron microscope. The investigation of the development of the precipitation processes was done by X-ray diffraction phase analysis. Findings: The microstructures and phase compositions of the residues, obtained from the elements, depend on life exhaustion extent. Practical implications: The presented method can be used for evaluation and qualification of structural changes in power station boiler and turbine components operating in creep conditions. Originality/value: The paper presents results of changes in the mechanical properties, structure and in the precipitation processes which are applied to evaluation for the condition of the elements in further industrial service.