I have been trying to analyze the microstructure of AISI 316L stainless steel and grain size. I have tried electrolitytically etching with 60%HNO3-40%H2O and with a disolution of oxalic acid. I have tried different voltages and times. The results are shown in the images. I think they are related to the metal rolling process. But I don't know if it's martensite, ferrite, slip bands, ... Or if it's a result of the etching. Could anyone help me to identify these bands and their origin?
To identify the phases you can use microhardness and XRD.
https://www.georgevandervoort.com/images/Metallography-General/Met-of-SS-Vol-9.pdf
Figura 33, yo creo que son bandas de deformación pero si quieres estar mas seguro si son otras fases atacala con otro reactivo quimico, yo uso agua regia diluida que usa una parte de agua, una parte de acido nitrico y una parte de acido clorhidrico y es por inmersion. En esos aceros puede encontrarse la fase ferrita delta.
Dulce Viridiana Melo Maximo
Gracias por la respuesta.
Ya conocía esa referencia. En la figura 33 las iamgenes que más se parecen son de la i en adelante y son para otras aleaciones. En otras de las figuras se observa martensita originada por la deformación y tambien es similar a lo obtenido.
He probado con aqua regia. Los resultados se pueden ver en la imagen. Aunque se ve distinto, también se observa unas bandas.
Las imagenes son de secciones transversales al eje longitudinal de la barra. Si analizo la microestructura de la superficie de la barra no aparecen las bandas.
Quería saber si son bandas de deformación o una fase como la martensita.
¿Las bandas de deformación son zonas del grano de austenita deformado, dislocaciones o son otra cosa?
Dear Sir,
I am not an expert but, it seems that the austenite grain borders doesn't give me the impression that the structure was mechanically deformed, grain shapes are not elongated. The elongated traces as well as the black spots seem to me resulting from the preparation of the sample itself.
Jean-Pierre Van Nieuwenhoven
Thanks for you answer.
I have used a standard polishing procedure and have tested different reagents by immersion or electrolytically. I have obtained similar results.
In the 10x image you can see the width of the steel plate and it is observed that the bands are parallel to the neutral zone of the center of the typical plate of the rolling process, that is why I think that the bands may be due to this process where compression it would be done between the upper and lower edge of the 10x image.
I agree that the grains are not deformed so I can't quite understand what these bands are. The bands can be an effect of the preparation but I wonder that they are so perfectly aligned. In the attached image I used aqua regia and there are also bands.
Could it be possible that the metal the your sample has been submited to a high temperature that has initiated a partial recristalisation phenomenon?
Jean-Pierre Van Nieuwenhoven
I don´t think so. It is a commercial steel plate.
en mi experiencia son zonas de granos deformados por el proceso de laminación pero quizá me equivoco, solo aparecen en la dirección de deformación y en la superficie de la barra no deberían verse. Si fueran otras fases con un reactivo de ataque especifico podrias revelarlas pero no creo que sea necesario. Si necesitas algun libro de reactivos quimicos escribeme por favor.
Do you have a chemical composition of your steel including P and S ? Maybe it is an effect of high inpurity level in your alloy batch?
To me, it does not look like deformation!
Paul Rosemann
Thanks for the reply.
I have observed the same structures in two AISI 316L plates of different thickness bought on different dates so I do not think they are due to impurities. How would impurities affect the microstructure?
Dear Dr. Jose Manuel Amado ,
I suggest you to have a look at the following, interesting papers:
-Metallography and Microstructures ofStainless Steels and Maraging Steels
Metallography and Microstructures ofStainless Steels and Maraging Steels
George F. Vander Voort, Gabriel M. Lucas, Elena P. Manilova
In: ASM Handbook, Vol. 9: Metallography and Microstructures G.F. Vander Voort, ed., 670 (2004)
Available at: https://www.georgevandervoort.com/images/Metallography-General/Met-of-SS-Vol-9.pdf
-Microstructure of austenitic stainless steelsof various phase stabilities after cyclicand tensile deformation
Anja Weidner, Alexander Glage, Stefan Martin, Jirí Man, Volker Klemm, Ulrich Martin,Jaroslav Polák, David Rafaja, Horst Biermann
Int. J. Mat. Res. (formerly Z. Metallkd.), 102 (11) 1374 (2011)
Available, as full text on RG, at: https://www.researchgate.net/publication/230765255_Microstructure_of_austenitic_stainless_steels_of_various_phase_stabilities_after_cyclic_and_tensile_deformation
-Superior strength and ductility of 316L stainless steelwith heterogeneous lamella structure
Jiansheng Li, Yang Cao, Bo Gao, Yusheng Li, and Yuntian Zhu
J Mater Sci, 53:10442–10456 (2018)
Available at: https://www.mse.ncsu.edu/zhu/wp-content/uploads/sites/27/2018/11/316L-Hetero-Li.pdf
Good work and my best regards, Pierluigi Traverso.
Pierluigi Traverso
Thank you for your replay.
I have the George F. Vander Voort references. I will read the other references that you suggest me.
The black spots in the microstructures seem pits. How long did you conduct electroetching in the acidic solution? what is the applied voltage?
We apply 1.1 v for 30-40 s. The features of the stainless steel microstructure are clarified without the black spots.
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