Electron backscattered diffraction study of ε/α′ martensitic variants induced by plastic deformation in 304 stainless steel

Abstract

The electron backscattered diffraction (EBSD) technique has been used to assess crystallographic features of the residual ␥ phase and the strain-induced /␣Ј martensites in a 304 stainless steel, tensile tested to 10 pct strain at T ϭ Ϫ60 °C. The martensitic transformation rate varies according to the ␥-grain orientation against the applied stress and the ␥-grain size. The ␣Ј-transformation textures as well as the ␥-misorientation spreads observed in specific ␥-grain orientations have been analyzed. Large misorientation spreads are observed in the less-transformed ␥ grains. This reveals an important crystallographic slip activity, even if less strain-induced martensite has been formed. A strong variant selection was detected in the cube-and Goss-oriented ␥ grains for which the transformation is less developed. For the {110}Ͻ1-11Ͼ and copper-oriented ␥ grains, the amount of ␣Ј martensite is significantly higher and the variant selection is less pronounced. This variant selection is then analyzed on at a local scale and is related to the presence of {111} ␥ localized deformation bands on which further /␣Ј martensites have nucleated.g → a¿ g → a¿

Deformation induced martensite in an AISI 301LN stainless steel: characterization and influence on pitting corrosion resistance

“…Main texture components are quite the same for the sample without deformation with the difference that the orientation {110}<111> moves toward {112}<111>, copper component. These results are in accordance with others works published in the literature [7][8][9] . The evolution of austenite texture with deformation for an AISI 304L stainless steel was studied by Ravi Kumar et al 8 and one of their conclusions is that the copper component will not increase density with high levels of deformation.…”

“…Kumar et al 7 , working with cold rolled AISI 304 stainless steel, also did not detected the presence of ε martensite. Gey et al and Humbert et al 9,10 characterized deformed AISI 304 samples and detected the presence of ε martensite. They have used a different apparatus.…”

“…The crystallographic texture of different low SFE steels has being studied by many authors [7][8][9][10] . It is expected a copper-type texture for austenite in 301LN and also in 316L steels.…”

“…For martensite, it is frequently to assume that the transformation texture follows relations like Kurdjumov-Sachs or Nishiama-Wasseman but true relations are irrational and cannot be expressed by rational numbers. The crystallographic set includes the habit plane and shape deformation apart from the orientation relation 9,10 . In this work, the deformation induced martensite was characterized in samples of commercial austenitic stainless steel AISI 301LN (low-stacking-fault-energy steel) by X ray diffraction, magnetic measurements, ebsd and atomic force microscope.…”

Modelling the microstructure of martensitic steels

“…Gey et al [38] in their analysis of an austenitic stainless steel discovered that not all the 24 martensitic variants form during transformation under tensile deformation. They demonstrated the selection of particular variants by comparing the measured pole figure with calculated pole figures for all 24 crystallographic variants of martensite.…”