Nanostructured surfaces

The Diffusion-Hardening Effect on the Corrosion Resistance and Technological Properties of High-Temperature Steel
Derecha D.O.1,3, Hruzevyich A.V.1,2
1 Institute of Magnetism Nat. Acad. of Sci. of Ukraine and Min. of Edu. And Sci. of Ukraine 
36b Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine Kyiv-03039, Ukraine. 
E-mail: dderecha@gmaul.com
2 Trypil’ska CHP 
UA-08720 Ukrainka, Kyiv Region, Obukhov District, Ukraine.
3 National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute 
37, Prosp. Peremohy, Kyiv, UA-03056, Ukraine

The service life of heating surfaces of the lower radiant section (LRS) of boilers with the power of 300MW and higher manufactured of steel pipes manufactured by DIN: 1.7715, WNr: 14MoV6-3 is limited to 20 thousand hours, in the area of burners and on the upper slit of the clipping tooth – 8-12 thousand hours. The main reason for the pipes cracking is their low orrosion resistance in combustion products of organic fuel [1, 2]. 
We report the results of research pipes diffusion hardening as an effective method for increasing the durability and reliability of power equipment are presented. The experience of commercial operation of pipes manufactured from diffusion chromized and heat-hardened steel on the heating surfaces of the supercritical pressure boilers are generalized. The possibility and effectiveness of this method on the example of capacities of Trypil’ska CHP are shown.
The diffusion chrome plating of pipes allows to increase their corrosion resistance in combustion products of organic fuel (pulverized coal and gas-oil fuel) by several times. It is shown that the durable strength of 100’000 hours for chromium-plated pipes is on the same level as for non-chrome plated pipes.

1.	Farrahi G.H., Ghadbeigi H. An investigation into the effect of various surface treatments on fatigue life of a tool steel // Journal of Materials Processing Technology. –2006. –174, –P. 318–324.
2.	Totten G.E. Steel heat treatment: Metallurgy and technologies / George E. Totten, editor, Taylor & Francis, Boca Raton, FL, 2007.