Sensitisation behaviour of grain boundary engineered austenitic stainless steel

Jones, R. D.; Randlè, Valerie

doi:10.1016/j.msea.2010.03.058

Cited by 120 publications

(63 citation statements)

References 22 publications

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“…That is to say the larger recrystallized grain, the larger the CSL boundary fraction. On the other hand, the CSL boundary fraction of about 0.5 can be easily attained by an ordinary primary recrystallization leading to an average grain size of 10-20 μm, whereas further multifold increase in the recrystallized grain size provide insignificant increase in the CSL boundary fraction to 0.6-0.7 [46,47]. Therefore, the presented approach can be used to predict the fraction of special boundaries in materials subjected to conventional processing methods including cold working followed by annealing, taking appropriate values of K and D 0 (as a size of recrystallization nuclei) in Equation (3).…”

Section: Philosophical Magazine 4193mentioning

confidence: 99%

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Σ3 CSL boundary distributions in an austenitic stainless steel subjected to multidirectional forging followed by annealing

Tikhonova

Kuzminova

Fang

et al. 2014

Philosophical Magazine

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The effect of processing and annealing temperatures on the grain boundary characters in the ultrafine-grained structure of a 304-type austenitic stainless steel was studied. An S304H steel was subjected to multidirectional forging (MDF) at 500-800°C to total strains of~4, followed by annealing at 800-1,000°C for 30 min. The MDF resulted in the formation of ultrafine-grained microstructures with mean grain sizes of 0.28-0.85 μm depending on the processing temperature. The annealing behaviour of the ultrafine-grained steel was characterized by the development of continuous post-dynamic recrystallization including a rapid recovery followed by a gradual grain growth. The post-dynamically recrystallized grain size depended on both the deformation temperature and the annealing temperature. The recrystallization kinetics was reduced with an increase in the temperature of the preceding deformation. The grain growth during post-dynamic recrystallization was accompanied by an increase in the fraction of Σ3 n CSL boundaries, which was defined by a relative change in the grain size, i.e. a ratio of the annealed grain size to that evolved by preceding warm working (D/D 0 ). The fraction of Σ3 n CSL boundaries sharply rose to approximately 0.5 in the range of D/D 0 from 1 to 5, which can be considered as early stage of continuous post-dynamic recrystallization. Then, the rate of increase in the fraction of Σ3 n CSL boundaries slowed down significantly in the range of D/D 0 > 5. A fivefold increase in the grain size by annealing is a necessary condition to obtain approximately 50% Σ3 n CSL boundaries in the recrystallized microstructure.

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Section: Philosophical Magazine 4193mentioning

confidence: 99%

“…For instance, a primary recrystallization is frequently used to obtain a large fraction of CSL boundaries [5,10,12,[45][46][47]. The most impressive results were obtained after annealing of slightly strained samples, which were characterized by large recrystallized grains [11,46,47].…”

Section: Philosophical Magazine 4193mentioning

confidence: 99%

Σ3 CSL boundary distributions in an austenitic stainless steel subjected to multidirectional forging followed by annealing

Tikhonova

Kuzminova

Fang

et al. 2014

Philosophical Magazine

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show abstract

“…This possibility of this form of corrosion must be taken into account when applying post-deformation heat treatment to enhance the ductility of nanometals [6][7][8][9], since the high strength is not accompanied by high ductility in the case of nanometals. Several methods have been proposed to avoid sensitising stainless steel, and thereby eliminating the risk of intergranular corrosion, including a reduction of the carbon content, the addition of elements like titanium or niobium and creating specially engineered grain boundaries [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Intergranular corrosion resistance of nanostructured austenitic stainless steel

2013

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Nanostructured metals and alloys possess very high strength but exhibit limited plasticity. Enhancement of the strength/ductility balance is of prime importance to achieve wide industrial applications. However, postdeformation heat treatment, which is usually used to improve plasticity, can lead to a decrease in other properties. In the case of austenitic stainless steels, heat treatment in the range from 480 to 815°C can increase their susceptibility to intergranular corrosion. The aim of the work reported in this paper was to determine if nanostructured austenitic stainless steel is susceptible to intergranular corrosion if heat treated for 1 h at 700°C. Samples of 316LVM austenitic stainless steel were hydrostatically extruded, in a multi-step process with the total true strain of 1.84 to produce a uniform microstructure consisting of nanotwins. These nanotwins averaged 21 nm in width and 197 nm in length. Subsequent annealing at 700°C produced a recrystallised structure of 68-nm-diameter nanograins. The heat treatment improved the ductility from 7.8 to 9.2 % while maintaining the ultimate tensile strength at the high level of 1485 MPa. Corrosion tests were performed in an aqueous solution consisting of 450 ml concentrated HNO 3 and 9 g NaF/dm 3 (according to ASTM A262-77a). The evaluation of the corrosion resistance was based on transmission and scanning electron microscopic observation of the microstructure and chemical analyses. The results revealed that both the as-received and HE-processed samples are slightly susceptible to the intergranular corrosion after annealing at 700°C for 1 h.

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“…Austenitic stainless steels possess excellent resistance to general corrosion; however, when they are subjected to a treatment like welding in the temperature range between 500°C and 800°C, they suffer from corrosion in forms of intergranular corrosion and intergranular stress corrosion cracking. This is generally attributed to sensitization as a result of chromium depletion which in turn is due to the chromium carbide precipitation in the grain boundaries [1][2][3][4][5]. Sensitization as a serious and momentous problem during welding of stainless steel has not been completely prevented by conventional techniques such as reduction of carbon content (below 0.03 wt.%), addition of strong carbide formers (such as titanium, niobium or zirconium), and solution heat treatment.…”

Section: Introductionmentioning

confidence: 99%

Prevention of weld-decay in austenitic stainless steel by using surface mechanical attrition treatment

2012

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Surface mechanical attrition treatment (SMAT) was applied to the samples of a type AISI 304 stainless steel in order to induce grain refinement as well as formation of twins. Transmission electron microscopy and X-ray diffraction analysis results showed that the average grain size at the surface of the SMATed sample was about 10 nm. The untreated and SMATed samples were then welded using a one-pass gas tungsten arc procedure. The heat-affected zone (HAZ) of the samples was examined by optical microscopy and corrosion tests. Results of the double loop electrochemical potentiokinetic reactivation tests showed that the degree of sensitization in the HAZ for the SMATed sample was very low as compared to that of the untreated one. The pre-SMATed sample was resistant to intergranular corrosion. This is mainly due to the formation of high density of twins which are not prone to carbide precipitation because of their regular and coherent atomic structure and extreme low grain boundary energy as compared with those of other grain boundaries.

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Sensitisation behaviour of grain boundary engineered austenitic stainless steel

Cited by 120 publications

References 22 publications

Σ3 CSL boundary distributions in an austenitic stainless steel subjected to multidirectional forging followed by annealing

Σ3 CSL boundary distributions in an austenitic stainless steel subjected to multidirectional forging followed by annealing

Intergranular corrosion resistance of nanostructured austenitic stainless steel

Prevention of weld-decay in austenitic stainless steel by using surface mechanical attrition treatment

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