Influence of metallurgical variables on sensitisation kinetics in austenitic stainless steels

Abstract

Austenitic stainless steels are the most favoured construction materials for various components required in chemical, petrochemical, fertiliser and nuclear industries. However, these steels are prone to sensitisation. In the sensitised condition, the steels are quite susceptible to intergranular corrosion and intergranular stress corrosion cracking in chloride and caustic environments resulting in the premature failure of the fabricated components during precommissioning and service periods. The topic of sensitisation has been of interest in studies worldwide. The studies included mechanism of sensitisation, test methods, data generation, and influence of several variables and protection methods. This article covers a review of important contributions to this topic with special emphasis on the influence of metallurgical variables. The present state of understanding is discussed in the following areas: mechanisms, test methods, sensitisation diagrams, influence of chemical composition, cold work and grain size, low temperature sensitisation, modelling and laser surface treatment. The need for further investigation in certain areas is highlighted.

A Comparative Study of Intergranular Corrosion of AISI 304 Stainless Steel and Chrome-Manganese Austenitic Stainless Steel

“…1) 300 series ASS will be more resistant to IGC than Cr-Mn ASS as it contains more amount of chromium. It is known that, by reducing the carbon content, more time is required to initiate sensitization phenomenon.…”

“…1,2) This excellent corrosion resistance of ASS is because of the formation of passive film of Cr 2 O 3 on the surface, when exposed to aqueous environment.…”

“…The sensitization behavior of 300-series ASS has been extensively studied. 1,3,[10][11][12] However, studies on the sensitization behavior of 200-series ASS are relatively few.…”

Enhancing Corrosion Resistance of 304 Stainless Steel GMA Welds with Electromagnetic Interaction

“…Sensitisation is a phenomenon in which of Cr-rich carbides, Cr 23 C 6 , precipitate and make the ASS's susceptible to localised attack in the form of pitting and intergranular corrosion in chloride containing electrolytes due to formation of Cr depleted zones near the grain boundaries. 1,2) Metallurgical methods such as reduction of carbon content, addition of Mo, localised heat treatments and grain boundary engineering have been used to overcome sensitisation in the heat affected zone (HAZ) of welded components. [2][3][4][5] Large magnetic fields have been used to modify solid phase transformations in ASS's because they act as external driving force for nucleation of martensite at preferential sites and change its kinetics of transformation, possibly due to alteration of the diffusion processes.…”

“…1,2) Metallurgical methods such as reduction of carbon content, addition of Mo, localised heat treatments and grain boundary engineering have been used to overcome sensitisation in the heat affected zone (HAZ) of welded components. [2][3][4][5] Large magnetic fields have been used to modify solid phase transformations in ASS's because they act as external driving force for nucleation of martensite at preferential sites and change its kinetics of transformation, possibly due to alteration of the diffusion processes. 6,7) This work investigates the effect of the application of an axial magnetic, in the order of mT, during fusion welding of cold rolled plates of AISI 304 stainless steel on the electrochemical behavior of the HAZ in terms of degree of sensitization (DOS).…”