Influence of heat flux and surface temperature on the intergranular corrosion of stainless steel

Abstract

The exposure tests followed by metallographic evaluation and the electrochemical reactivation measurements in double-loop (DL-EPR) modification were used for investigation of the influence of non-boiling heat transfer on initiation and rate of propagation of intergranular corrosion (IGC) of sensitized austenitic stainless steel EN 1.4301 (AISI 304) in sulfuric acid solutions. The influence of heat flux and surface temperature was ascertained separately. The susceptibility to IGC and the rate of crack propagation increased with the surface temperature. Heat flux from metal to solution at constant surface temperature facilitated the IGC initiation, but at the same time it caused a drop of the corrosion attack depth in the metal. The increase of the heat flux by 10 kW m À2 in a range from 0 to 42 kW m À2 led to a drop of the maximum depth of cracks formed after subsequent bending the specimen, in average by 8%. The overall danger of corrosion was lower at positive heat flux between metal and solution than under isothermal conditions at constant surface temperature of the metal. The intensification of heat flux by 10 kW m À2 had the same effect on the IGC as a change of the surface temperature by less than 2 K. Therefore, the effect of the heat flux on IGC of the heat exchangers operating under non-boiling conditions may be considered as relatively less important than the effect of the surface temperature.

Influence of heat transfer on corrosion behaviour of materials for radioactive waste canisters in synthetic bentonite pore water and bentonite suspension

“…Obecně může mít tepelný tok negativní i pozitivní dopad na korozní napadení. Byl pozorován pozitivní vliv v případě mezikrystalové koroze, kdy zvýšená teplota v materiálu rozšiřovala plochu aktivní ochuzené zóny a zpomalovala propagaci napadení do hloubky materiálu [1]. U bodové koroze naopak zvýšená rozpustnost kyslíku o povrchu a zrychlený transport zvyšují odolnost pasivní vrstvy a znesnadňují iniciaci napadení.…”

Influence of welding current intensity on susceptibility to intergranular corrosion in welded joints of stainless steel

“…Senzibilizacija nerđajućeg čelika prema interkristalnoj koroziji se najčešće javlja u zavarenim spojevima, u zoni uticaja toplote (ZUT-u) koja je paralelna metalu šava, ili prilikom žarenja u cilju smanjenja zaostalih naprezanja. Senzibilizacija se češće javlja pri zavarivanju debelih ploča, što je posledica unesa toplote i različitih brzina hlađenja [4,5]. Jačina struje zavarivanja je u direktnoj korelaciji sa unetom količinom toplote u zavareni spoj, odnosno sa pojavom različitih strukturnih transformacija u zavarenom spoju (zoni uticaja toplote i metalu šava).…”

“…Jačina struje zavarivanja je u direktnoj korelaciji sa unetom količinom toplote u zavareni spoj, odnosno sa pojavom različitih strukturnih transformacija u zavarenom spoju (zoni uticaja toplote i metalu šava). Pri većim jačinama struja zavarivanje dolazi do intenzivnijih strukturnih transformacija u zavarenom spoju, odnosno do senzibilizacije zavarenog spoja [5]. Ispitivanje sklonosti nerđajućih čelika prema interkristalnoj koroziji se često izvodi primenom metode elektrohemijske potenciokinetičke reaktivacije sa dvostrukom petljom, DL EPR [6][7][8].…”

DEIS evaluation of the relative effective surface area of AISI 304 stainless steel dissolution process in conditions of intergranular corrosion

“…A search for a rapid, quantitative and non-destructive test method, lead many researchers to develop double-loop electrochemical potentiokinetic reactivation (DL-EPR) tests [2,3,[19][20][21][22][23][24][25]. The DL-EPR technique has especially found the application for detecting DOS of AISI 304 stainless steels.…”