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Jachym R.,Instytut Spawalnictwa Institute of Welding | Lomozik M.,Instytut Spawalnictwa Institute of Welding | Kwiecinski K.,Instytut Spawalnictwa Institute of Welding | Urzynicok M.,ZELKOT Boiler Elements Factory | And 2 more authors.
ASM Proceedings of the International Conference: Trends in Welding Research | Year: 2013

Dynamic development of steels used in power engineering industry for the production of boilers characterised by supercritical parameters poses new welding challenges. The introduction of new combinations of alloying elements aimed at obtaining the best possible mechanical properties, including creep resistance, affects the weldability of new steels. Each of the latter must undergo many tests, particularly as regards bending and welding, in order to enable the development of technologies ensuring failure-free production and assembly of boiler systems. Martensitic steels containing 9% Cr, used in the manufacturing of steam superheaters, are characterised by good creep resistance and, at the same time, low oxidation resistance at a temperature in excess of 600°C. In turn, steels with a 12% Cr content are characterised by significantly higher oxidation resistance, but accompanied by lower strength at higher temperatures, which translates to their limited application in the production of boilers operating at the highest parameters. The niche between the aforesaid steels is perfectly filled by austenitic steels, the creep resistance and oxidation resistance of which are unquestionable. This article presents experience gained while welding similar joints of steel TEMPALOY A-3 and dissimilar joints of steels TEMPALOY A-3 and T91, with the use of EPRI87. The tests involving the said steel grades belong to the very few carried out in the world. Copyright © 2013 ASM International® All rights reserved.


Hashizume S.,TenarisNKKTubes | Nishizawa N.,Waseda University | Yanagihara A.,Waseda University | Sakai J.,Waseda University
Materials Science and Technology Conference and Exhibition 2010, MS and T'10 | Year: 2010

Mo addition to martensitic stainless steels improves corrosion resistance of the steel in CO2 environments. This research was performed to clarify the role of Mo on 13%Cr steels in CO2 environments from the view points of corrosion film analysis by GDS. Mo enrichment was observed at outer layer in corrosion film of Mo additional steel when corrosion rate was small. This will lead to excellent corrosion resistance in CO2 environments. Copyright ©2010 MS&T'10®.


Urzynicok M.,ZELKOT | Jachym R.,Institute of Welding | Kwiecinski K.,Institute of Welding | Mariani P.,Tenaris Group | Minami Y.,TenarisNKKTubes
Advances in Materials Technology for Fossil Power Plants - Proceedings from the 7th International Conference | Year: 2014

Dynamic development of steels used in power engineering industry for the production of boilers characterised by supercritical parameters poses new welding challenges. The introduction of new combinations of alloying agents aimed at obtaining the best possible mechanical properties, including creep resistance, affects the weldability of new steels. Each of the latter have to undergo many tests, particularly as regards bending and welding, in order to enable the development of technologies ensuring failure-free production and assembly of boiler systems. Martensitic steels containing 9% Cr, used in the manufacturing of steam superheaters, are characterised by good creep resistance and, at the same time, low oxidation resistance at a temperature in excess of 600°C. In turn, steels with a 12% Cr content are characterised by significantly higher oxidation resistance, but accompanied by lower strength at higher temperatures, which translates to their limited application in the production of boilers operating at the highest parameters. The niche between the aforesaid steels is perfectly filled by austenitic steels, the creep resistance and oxidation resistance of which are unquestionable. This article presents experience gained while welding dissimilar joints of advanced steels TEMPALOY AA-1 and T92, with the use of EPRI P87, Inconel 82 and Inconel 617 filler metals. The tests involving the said steel grades belong to the very few carried out in the world. Copyright © 2014 Electric Power Research Institute, Inc. Distributed by ASM International®. All rights reserved.


Hashizume S.,TenarisNKKTubes | Nakayama T.,Toshiba Corporation | Sakairi M.,Hokkaido University | Fushimi K.,Hokkaido University
Zairyo to Kankyo/ Corrosion Engineering | Year: 2011

Low Carbon-13%Cr martensitic stainless steels have been widely used for line pipe application because of their high strength and excellent corrosion resistance in corrosive conditions. Recently, both laboratory and field experiences related to cracking near fusion line of these steels weld joints in hot acid environments have been published. In this paper, SCC (Stress Corrosion Cracking) mechanism near fusion line of low C..13..Cr welded joints is discussed. Especially, initiation process is focused. Mainly electrochemical measurement using solution flow type micro-droplet cell and surface analysis of weld joints are conducted. In the evaluation of electrochemical behavior of low C-13%Cr welded joints with and without PWHT (Post Welded Heat Treatment) by the use of a solution flow type micro-droplet cell, PWHT leads to more noble and stable potential in HAZ (Heat Affected Zone) compared to as-welded condition. In the HAZ portion of the as-welded joint, Cr depleted layer was detected under welding scale with the use of GDS (Glow Discharge Spectrometer). PWHT was confirmed to eliminate Cr depleted layer under welding scale. This can be an initiation of SCC near girth welded joint in hot acid environment. Finally, mechanism of SCC initiation near fusion line of as-welded joint was proposed. Localized corrosionwould start at Cr depleted layer under welding oxide scale. This dissolution was also accelerated by a galvanic effect due to a large cathode area of base metal.


Hashizume S.,TenarisNKKTubes | Trillo E.,Southwest Research Institute | Kobayashi N.,TenarisNKKTubes
NACE - International Corrosion Conference Series | Year: 2013

Recently, CO2 has been highly pressurized in environments such as CO2 injection for stimulation and CO2 storage to reduce CO2 amount at surface. When CO2 is highly pressurized, a supercritical CO2 is created under conditions both over 31.1 degrees C and 72.9 atm. It is well known that water under pressurized CO2 gas leads to severe CO2 corrosion with carbon steel. Thus, CRAs are effective to prevent CO2 corrosion. In the supercritical CO2, corrosion behavior of carbon steel was reported. The corrosion rate of carbon steel was lower than the predicted model. From the view point of phase difference of CO2, the effect of CO2 in supercritical phase on CRAs is not clear. In this paper, the effect of CO2 in supercritical phase up to 300 bar on 13%Cr steels are examined. The effect of Oxygen on corrosion performance of 13%Cr steels under supercritical CO2 was also examined. The effect of supercritical CO2 on corrosion rate of 13%Cr steel was similar to or less than that of gas CO2. More than 200bar supercritical CO2 lead to localized corrosion. With 0.45bar Oxygen condition, crevice corrosion of 13%Cr steels in supercritical CO2 was recognized. Super-martensitic stainless steel showed better corrosion resistance than Type 420 in all conditions. ©2013 by NACE International.

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