THE EFFECT OF TECHNOLOGY OPERATION LIKE BENDING ON PROPERTIES OF NEW AUSTENITIC STEELS FOR APPLICATION IN BOILERS WITH HIGHER STEAM PARAMETERS

This paper focuses on the influence of the cold bending process on stress - strain characteristics of materials SUPER304H, HR3C, Tp347HFG that can be used for superheaters and reheaters of newly built or refurbished power plant boilers. The qualification tests were carried out on bends in two dimensions of tubes and on several bending radii to verify the effect of cold bending technology. In the year 2013 there was tested new bend radius. To obtain reliable information, a tensile test, a hardness test and metallographic examination were used on material from the straight tubes of the bends, drawn and compressed parts whose results are presented in this paper and are an extension of the results obtained from the new bend radius compared to last year's article. We have acquired new information about the stress-strain behaviour of advanced structural materials thanks to the realization this experimental program. We can give precision to correlation relations between SPT and conventional tensile tests for austenitic materials presented in the year 2013. In the context of the project there were performed simulation calculations that used the experimental results focused on verification of the deformation in bending parts, the thinning of the wall thickness and determination of the thermodynamic stability of phases. Some of them are described in this article. The tests have been carried out under the grant project of the Technology Agency of the Czech Republic TA01010181 with the name Bending-tubes-technology for superheaters and inter-superheater tubes for progressive boiler construction which VITKOVICE POWER ENGINEERING a.s. researches in cooperation with companies named UJP a.s. and SVUM a.s.