Cold deformation effect on the microstructures and mechanical

properties of AISI 301LN and 316L stainless steels

 

Paulo Maria de O. Silvaa, Hamilton Ferreira G. de Abreub, Victor Hugo C. de 

Albuquerquec, Pedro de Lima Netob, João Manuel R.S. Tavaresd,  

                                                            a Petróleo Brasileiro SA, Rodovia CE 422, km 0, Complexo Portuário do Pecém, Salgadinho, 61600‐000, 

Caucaia – CE, Brazil / Universidade Federal do Ceará (UFC), Departamento de Engenharia de 

Teleinformática (DETI), Laboratório de Telecomunicações e Ciências e Engenharia de Materiais (LOCEM), 

CEP 60455‐760, Fortaleza, Ceará, Brazil 

b Universidade Federal do Ceará (UFC), Centro de Tecnologia, Departamento de Engenharia Metalúrgica 

e de Materiais, Campus do Pici Bloco, 714, Pici, 60455‐760, Fortaleza ‐ CE, Brazil 

c Universidade de Fortaleza (UNIFOR), Centro de Ciências Tecnológicas (CCT), Núcleo de Pesquisas 

Tecnológicas (NPT), Av. Washington Soares, 1321, Sala NPT/CCT, CEP 60.811‐905, Edson Queiroz, 

Fortaleza, Ceará, Brazil 

d Faculdade de Engenharia da Universidade do Porto (FEUP), Departamento de Engenharia Mecânica 

(DEMec) / Instituto de Engenharia Mecânica e Gestão Industrial (INEGI), Rua Dr. Roberto Frias, S/N ‐ 

4200‐465 Porto, Portugal  Corresponding author. Tel.: +351 22 5081487; fax: +351 22 5081445. 

E‐mail addresses: paulomsilva2003@yahoo.com.br (P.M.O. Silva), hamilton@ufc.br (H.F.G. de Abreu), 

victor.albuquerque@fe.up.pt (V.H.C. de Albuquerque), pln@ufc.br (P.L. Neto), tavares@fe.up.pt 

(J.M.R.S. Tavares). 

 

i.exe

Abstract

As austenitic stainless steels have an adequate combination of mechanical resistance,

conformability and resistance to corrosion they are used in a wide variety of industries,

such as the food, transport, nuclear and petrochemical industries. Among these

austenitic steels, the AISI 301LN and 316L steels have attracted prominent attention

due to their excellent mechanical resistance. In this paper a microstructural

characterization of AISI 301LN and 316L steels was made using various techniques

such as metallography, optical microscopy, scanning electronic microscopy and atomic

force microscopy, in order to analyze the cold deformation effect. Also, the

microstructural changes were correlated with the alterations of mechanical properties of

the materials under study. One of the numerous uses of AISI 301LN and 316L steels is

in the structure of wagons for metropolitan surface trains. For this type of application it

is imperative to know their microstructural behavior when subjected to cold

deformation and correlate it with their mechanical properties and resistance to

corrosion. Microstructural analysis showed that cold deformation causes significant

microstructural modifications in these steels, mainly hardening. This modification

increases the mechanical resistance of the materials appropriately for their foreseen

application. Nonetheless, the materials become susceptible to pitting corrosion.

Keywords: A. Ferrous Metals and Alloys; G. Image analysis, G. Metallography

1. INTRODUCTION

Stainless steels first appeared when scientists were trying to develop a state of

passivity for ferrous alloys; a state that would not visibly show any oxidization, as was

initially produced by Faraday [1]. Harry Bearley’s experiment in 1912, which was the

addition of 12.5% Cr (chromium) to Fe (iron), initiated commercial production of

stainless steels [2]. This material had a martensitic microstructural matrix. Later,

following the works of Guillet (France) and Giesen (Germany), Monnartz developed the

Fe-Cr-Ni (iron-chromium-nickel) steels in Essen (Germany), giving origin to stainless

steels of the austenitic matrix, universally known as 18% Cr – 8% Ni [3].

There are five major classes of stainless steels [3]: ferritic, martensitic, duplex,

hardened by precipitation, and austenitic, the latter being the focus of this work.

The application of austenitic stainless steels in the food, petrochemical and

nuclear industries is due to their combination of good conformability, mechanical

resistance and resistance to corrosion. Specifically, steel 301, according to the American

Iron and Steel classification (AISI), is widely employed in the making of kitchen sinks

and train wagon structures for underground or surface metropolitan trains. The highest

level of mechanical resistance of this 301 steel is in the AISI3xx steel family; however,

it does not show such a satisfactory level in terms of corrosion [4].

As steel 301 is mechanically unstable, deformation induces extensive martensitic

transformation, whose crystalline structure may be compact hexagonal (CH), usually

known as martensite  or body centered cubic (BCC) designated as martensite α’ [4, 5].

It is known that martensitic transformation, like other changes, derived from shear

stress, which cause microscopic wave propagations on the surface of the material [6]

and an increase in volume resulting in residual tensions [7, 8].

Stainless steels owe their corrosion resistance to passive oxide films that are

formed on their surfaces. However, their level of resistance is especially compromised

in settings where there are Cl (chlorine) ions or halogens [1, 4]. In the case of steels of

the 3xx series, notably AISI 301 and 304, the martensitic transformation may cause the

rupture of the passive film due to higher density of flaws and generate residual stress or

a galvanic effect caused by the presence of two distinct phases [9]. Corrosion resistance

in more mechanically stable steels may be reduced by deformation, and the introduction

of flaws [10]. Also the shrinkage of microstructures makes austenitic steels even more

vulnerable to corrosion [11].

Many research studies concerning austenitic steels have been carried out. For

instance, the effects of thermo-mechanical parameters were investigated by Eskandari et

al. [12] in order to achieve a nanocrystalline structure in the as-cast AISI 301 stainless

steel. Silva et al. [13], evaluated the effect of welding heat cycles on AISI 316L

austenitic stainless steel corrosion resistance in a medium containing heavy petroleum.

Korkut et al. [14], analyzed the optimum cutting speed when turning AISI 304

austenitic stainless steel with cemented carbide cutting tools. Finally, Wasnik et al. [15],

studied the precipitation in a AISI steel using a combination of differential scanning

calorimetry, electrical resistivity measurements and transmission electron microscopy,

and identified the coherent precipitation, its coarsening, the initiation of the grain

boundary precipitation, σ phase and lastly the M23C6 precipitation.

Different studies on the effect of cold deformation on stainless steels have been

made, for example: to correlate processing parameters and strain-induced martensitic

transformation in AISI 301 stainless steel [16]; to evaluate magnetic properties and α′

martensite in AISI 301LN stainless steel [17]; to analyze the effect of process

parameters on the properties of spot welded cold deformed AISI 304 grade austenitic

stainless steel [18]; and to study the evolution of the microstructure and texture of a

AISI 316L austenitic stainless steel [19].

A metropolitan train project is under way in a costal city with a saline

environment including chlorides and AISI 301LN and 316L steels have been selected to

build the wagon structures. The aim of this work was to corroborate the excellent

mechanical properties usually pointed out for these steels and analyze, at the

microstructural level, the influence of cold deformation imposed by lamination with

these environmental conditions. A microstructural analysis was carried out using the

different techniques of optic microcopy (OM), scanning electronic microscopy (SEM)

and atomic force microscopy (AFM), and the resulting microstructures found were

correlated with the mechanical properties of the materials to confirm their adequacy for

their projected use. Even though the mechanical properties of these steels are relatively

well known, the study of the microstructural variations by imposing cold deformations

using the techniques of analysis above mentioned is still incipient. Also the correlation

of the microstructural variations found with the alterations of mechanical properties of

the same steels has not yet been fully validated. This work is, therefore, contributing to

further the knowledge of AISI 301LN and 316L steels, particularly concerning their

behavior when subjected to cold deformations.

This paper is organized as follows: The materials used are detailed in the

following section, which also describes the steps taken for their microstructural

evaluation. In Section 3, the results are presented and discussed. Finally, in Section 4,

the conclusions of the work are pointed out.

2. MATERIALS AND METHODS

Two laminated steel sheets measuring 50x25x1.9 mm3, one of AISI 316L steel

and the other of AISI 301LN steel with a superficial reduction of 4%, were analyzed in

their as-received states. Table 1 shows the chemical composition of the AISI 301LN

and 316L sheets. To obtain the accurate composition of the steels, the Cr, Ni and Mo

(molybdenum) elements were measured using an energy dispersive x-ray detector (EDS

– (*)), and the N (nitrogen) was determined via coulometric measurement (**). Mass

spectrometry was used for all the other elements.

The cold deformation was carried out with a pilot laminator, a bench and duo

type, without reversion, and with 43.5 mm diameter cylinders that were 106 mm long,

Figure 1. This laminator was attached to a reducer system connected to an 250 W

electric motor with 1750 rpm. After lamination, the test bodies, 10 for each type of steel

were prepared with dimensions of 50x2.5x1.9 mm3. The thickness reduction was carried

out at room temperature with common lubricating oil and adopting a reduction of 0.1

mm per each consecutive pass for approximately 3 s, until two levels of thickness: 1.4

mm (26% or true deformation of 0.31) and 1.0 mm (47% or true deformation of 0.64)

were obtained; for a detail explanation on the lamination, see [20]. Table 2 gives the

deformation levels and average deformation rates in each pass to reduce the thickness.

For the microstructural characterization, an Olympus optic microscope, model

BX51M (Japan) with a digital video camera attached to a computer was used to acquire

the images. A Philips scanning electron microscope, model XL-30 (USA), was used to

detect the secondary electrons (SE), backscattering electrons (BSE), as well as a

detector of energy-dispersive X-ray spectroscopy EDS (USA). For high resolution

images, a Digital Instruments atomic power microscope, model Nanoscope (USA), with

a digital camera was used to acquire images of the samples exhibited on the monitor.

The camera visor was also used to position the microscope probe over the sample.

The metallographic preparation was carried out conventionally for all samples.

First they were immersed in Bakelite type resin and then were sandpapered until half of

their original thickness. After which, the reagents of Villela (1 g of picric acid, 5 ml of

HCl (hydrogen chloride) and 100 ml of ethanol), with etching time between 10 to 13

minutes for AISI 301LN and between 15 to 17 minutes for AISI 316L, and Behara (0.3

to 0.6 g of metabisulfite of potash, 20 ml of HCl and 100 ml of distilled water), with

etching time from 15 seconds to 1 minute for both steels, and a reagent for electrolytic

etching (30% of HNO3 (nitric acid) in de-ionized water), with current between 0.12 and

0.5 A and tension between 1.5 and 6.0 V, were used. The etching time, after

stabilization of the corrosive reaction, was from 2 to 3 minutes for the AISI 301LN steel

samples and 3.5 to 5 minutes for the AISI 316L steel samples.

A commercial image analysis system was used to obtain the stereological

information of the samples in the as the received and laminated conditions. All images

had a resolution of 640X512 pixels and included the whole field of the optic

microscope. The grain size of the sheets as received was also measured with the optic

microscope using the intercepts technique, see [21], magnification of 1000X and

counting 400 intercepts.

The volumetric fraction of the second phase was evaluated using OM captured

images with 200X magnification and a threshold applied in the grey contrast scale.

Some 10 to 40 regions were examined for each sample. The exposed surfaces of the

samples were also analyzed by the same technique with images of SEM in secondary

electrons (SE) and back scattering electrons (BSE) with magnification from 2,500X to

10,000X. The inspection in AFM was carried out using the deflection, attrition and

height modes either with normal sweep or lateral force microscopy (LFM) in areas of

analysis with 10 m of maximum size.

3. RESULTS AND DISCUSSION

The volumetric fraction (VF) measurements of the AISI 316L and 301LN

austenitic stainless steel samples were made using X-ray diffractogram curves, adjusting

them with the pattern decomposition program - PROFIT (Philips, Eindhoven, The

Netherlands) and calculating the associated areas.

The VF values obtained point to the growth of the second phase fraction with an

increment of deformation, which is the expected behavior for the formation of

martensite α’ in AISI steels [22]. Table 3 shows the deformations that the steels went

through during lamination, their final thickness after lamination, and the percentages for

all the detected phases with their respective standard deviations.

In the case of AISI 316L, notably the austenitic matrix, the second phase fraction hardly

varied with the deformation. Normally the appearance of the martensite α’ at room

temperature at the levels of deformation employed in AISI 316 steel is not observed

[23]. However, it is observed when subjected to cyclical deformations [24, 25]. This

observation sustains the conclusion that the only phase that meets the requirements,

within the experimented conditions used here, is the ferrite δ that is formed during the

solidification of the ingot [3]. This was also described by Nebel and Eifler with a AISI

321 steel dowel in a fatigue study [25]. The small variation encountered may be

attributed to heterogeneity of the original sheet. Therefore, our findings are in line with

previous works: Llewellyn, in a review of the influence of composition on the work

hardening behavior of commercial grades of austenitic stainless steels, concluded that in

unstable grades, the formation of strain induced martensite during fatigue testing

reduces the crack propagation rate due to perturbation of the stress field around the

advancing crack tip [23]. Also the composition design for the development of the

optimum work hardening rate was discussed, particularly for end applications. Maeng

and Kim studied the characteristics of the cyclic plastic strain zone of AISI 316L and

316LN stainless steels at the crack tip by using micro hardness tests, X-ray diffraction

and transmission electron microscopy [24]. Thus, these authors discussed the

improvement of the fatigue crack growth resistance of the AISI 316LN stainless steel in

relation to the degree of crack closure, strain induced martensite transformation and the

dislocation structure in the cyclic plastic stain zone at the fatigue crack tip. On the other

hand, Nebel and Eifler presented an investigation to characterize the cyclic deformation

behavior and the plasticity-induced martensite formation of metastable austenitic

stainless steels at ambient and high temperatures, taking into account the influence of

the alloying elements titanium and niobium [25]. The experiments conducted yielded

characteristic cyclic deformation curves and corresponding magnetic signals according

to the actual fatigue state and the amount of martensite. The fatigue behavior of the steel

studied was characterized by cyclic hardening and softening effects that are strongly

influenced by specific loading conditions. Additionally, martensite formation varied

with the composition, loading conditions, temperature and number of cycles. Therefore,

these works aimed to evaluate austenite steels, mainly, by mechanical test and, in [24],

to establish a simple correlation between mechanical properties and transmission

electron microscopy. Hence, besides the aforementioned corroboration, this paper

complements the findings of these previous works by studying the cold deformation of

the AISI 316L and 316LN stainless steels in detail.

The presence of the α’ phase in AISI 301LN steel is because the initial condition

was obtained by hot lamination, which predisposes both phases in the residual

deformation. The increment of deformation to 0.31 provokes a relaxation of

compression on α’ and a relief of deformation (traction) treated on the γ phase. The

increment of deformation to 0.64 alters only very slightly the deformation state of the

phases, which suggests that the material has reached its shrinkage saturation capacity.

In the case of AISI 316L steel, there is also residual stress in the initial condition

in the γ phase. Upon imposing deformation a compression of the δ phase and increase of

the ’  in γ take place. It is very likely that this is due to the hardening of both phases.

The increment of deformation provokes a relaxation of compression on the δ phase

accompanied by a discreet relief in that does not correspond to the magnitude of

relaxation. This is evidence of deformation microstructure recovery, the phenomenon

associated to the change in the arrangement of discrepancies with a consequent change

in the deformation regime [26, 27].

In both steels, it was impossible to unequivocally determine the parameter D of

the phases. The fact of introducing deformation in the phase contributed to hardening

it, which would allow the formation of discrepancy cells and even sub-grains [28]. This

may be a justification for such low D values.

The values in Table 3 indicate that the increase of deformation to 0.31 did not

cause a considerable change in the VF of the α’ phase in AISI 301LN steel, despite a

distribution change of α’ to a more regular mode. Upon increasing the level of

deformation to 0.64, the VF presented a discreet increase. These results suggest that the

0.64 deformation level could perhaps be close to the saturation level of the α’ fraction.

With the AISI 316LN steel, the variation in the VF of the δ phase is not

significant with the increase of deformation, as was expected. This proves the

mechanical stability of AISI 316LN steel, which was also observed by Dewidar et al.

[29] with compression tests and by Le et al. [30] through electromechanical techniques.

Also, OM revealed that the VF is kept at a low level and is practically unaltered with a

deformation increase.

Figures 2a and 2b show the appearance of the austenitic grains, under the studied

conditions, for the AISI 301L and AISI 316LN steels, respectively, considering that the

initially equiaxial grain sizes (GS) for these materials were 14.75 ± 0.74 m (ASTM

grain nr. 8.7) for AISI 301L steel, and 24.75 ±1.24 m (ASTM grain nr. 7.3) for AISI

316LN steel. The grains of these samples were normalized in an electrical furnace at

950 ºC for 2 hours as can be seen in the micrographs. In Figure 2c, corresponding to the

initial condition of AISI 301L steel, in which the  and α’ phases were observed, and

the OM analysis indicated that the distribution of the phase was irregular. Superior

magnification confirmed that the phases are really intertwined. The α’ phase is in the

form of plaques and appears in higher proportions than the phase. 

Deformation caused grain hardening of the steel studied (Figure 3), affecting its

mechanical properties by increasing its resistance, flow stress, hardness and fragility;

and by reducing its malleability, ductility and resistance to corrosion [31].

Upon imposing a deformation of 0.31 to AISI 301L steel, the plaques of the α’

phase are seen to be less aggregated than initially, and the retained  regions are more

distinct, indicating some deformation, Figure 4a. On the other hand, the phase is better

distributed and morphologies similar to the needles of martensite are clearly seen.

Figure 4b shows a 0.64 deformation and a small island of  regularly distributed in the

martensite could be distinguished, which indicates there was an increase in deformation.

A metallographic analysis of the AISI 316L steel for the deformation of 0.31 in

Figure 5a shows that the VF of the δ phase is practically unaltered in comparison to

steel under the as-received state (Table 3); additional, the austenitic grains appeared

deformed. This steel presents a higher ferrite δ fragmentation level after undergoing a

deformation of 0.64 compared with the deformation of 0.31, as shown in Figure 5b.

Additionally, the δ phase is aligned with the lamination direction and the austenitic

grains are more deformed.

An illustration of the microstructural aspects of AISI 301LN steel, deformed at

0.64, using a SEM can be seen in Figure 6a. Also, Figure 6b shows the morphology of

the α’ phase of the AISI 316L steel sample. This Figure indicates that this phase has

plaques and interconnected needles that are intertwined with the phase. The α’ phase

is higher than the phase, which is usually associated to the martensite phase. This

transformation results in shearing that causes superficial relief [6]. Additionally, the

phase is more unevenly distributed in the lower proportions than the α’ phase, as was

revealed by OM. The crystallographic texture induced in the AISI 301LN steel samples

was notable only for martensite α’ that underwent fiber reinforcement <111>//DN due

to the deformation. Evidence was found that martensite α’ was formed at the

expenditure of fiber β of the phase following the Kurdjumov-Sachs orientation

relationship.

Figure 7a shows the fragmentation of the lattice work of interconnected plaques

clearly and here the  regions are visible and well distributed. The porous aspect of the  

phase suggests an increment of deformation that increases the concentration of

discrepancies and causes corrosion by pits due to a more effective chemical etching.

Figure 7b shows the AISI 301LN steel sample with a 0.64 deformation where the

phase  is difficult to distinguish and only a few plaques of α’, which are more

fragmented, still stand out at the very bottom that is full of pits. These pits may cause an

increase of corrosion vulnerability [32, 33]. This type of corrosion is localized and

consists of the formation of small cavities with considerable depth.

Figure 8a presents AISI 316L steel in the as receive state, in which is observed a

normalized structure for the austenitic grains. The δ phase is dispersed and oriented

according to the direction of the sheet’s original lamination. By imposing a 0.31

deformation, Figure 8b, the proportion of the δ phase does not seem to alter, although it

fragments it and deforms the phase. A further increase of deformation to 0.64 has the

same effect with the difference that the regions of the δ phase were more easily

distinguishable than for the AISI 316L steel sample with deformations of 0.31.

An image representing the microstructural aspects by atomic force microscopy

(AFM) is presented in Figure 9a. The image is related to two sweeps using lateral force

microscopy (LMF), height, attrition and deflection modes, showing the existence of two

distinct regions in terms of interaction. One of these regions is apparently formed by

small nanometric subunits (’ phase), while the second one presents irregularities in the

likeness of wrinkles that indicate that the phase is more sensitive to chemical flare (

phase). The morphology looks like needles, Figure 9a, or laths, as can be seen in Figure

9b, with much greater heights than the phase, thus confirming unequivocally to be

martensitic regions.

Figure 10a, obtained by LFM, illustrates a region of the AISI 301LN steel

sample with deformation of 0.31 containing ’ and  phases through deflection, height

and attrition modes. In addition, Figure 10b corresponds to a specific sweep over a ’

phase showing its nanometric subunits. These subunits correspond to ellipses of axis

160x70 nm2. Lee and Lin [34] evaluated this same structure based on its

morphology/geometry in a AISI 304 L steel using TEM. Figure 10c presents a

digitalized image from the AFM probe, of a triangle over a region similar to the one that

was swept for the image capture in Figure 10b. This indicates that the regions that are

darkened due to the Behara reagent are directly associated with the martensite regions,

validating the VF measurement of the OM. Figure 11a shows a region of the AISI 301

LN sample with a deformation of 0.64, presenting the and α’ phases and the subunits

that compose α’ and again we can distinguish the standards of the two phases in AFM

observed for other samples. For the AISI 316L steel sample, it was difficult to identify

the ferrite δ regions clearly. Figure 11b confirms once more that the austenitic grains

were re-crystallized. Figure 11c confirms that in the interior of the austenitic grain, there

is another phase that is attributed to . Figure 11d corresponds to the sample AISI 316L

steel with a 0.31 deformation and clearly shows the effect of deformation on the

austenite that is starting to present irregular contours due to local changes of orientation

[28].

Figure 12a, which presents an AFM image, shows the effect of the increment of

deformation on the austenite of the AISI 316L steel sample with a 0.64 deformation.

The attrition image shows regions with different responses to attrition and in bands,

which suggests that these regions may correspond to slide bands. Lee and Lin [34]

obtained images from TEM with shearing bands similar in level to the next

deformation; however, with a higher deformation rate. Figure 12b presents an elliptic

region of ferrite δ that has major and minor axis of sizes of around 6 m and 3 m,

respectively, which are responsible for the embrittlement effect in stainless steels. The

aspect is totally distinct from what is seen for the martensite α’ that is also associated to

embrittlement in this type of material, which increases its mechanical resistance and

decreases its ductility. Also Figure 12c shows the presence of ferrite δ and phases by

using a probe during a sweep through LFM over the same region as Figure 12b.

4. CONCLUSIONS

A microstructural evaluation of AISI 301LN and 316LN steels was carried out

using the different techniques of optic microscopy, scanning electronic microscopy and

atomic force microscopy. Also, the microstructures of these steels were correlated with

their mechanical properties. This study is of particular importance due to the integrated

transportation project that will use AISI 301LN and 316L steels in the construction of

the train wagons. Thus, the reliable and detailed knowledge of these materials, achieved

in this work, is fundamental for the success of the above mentioned project.

The main important results of this experimental work can be summarized as

follows:

1. Plastic deformation caused the formation of martensite α’ in the AISI 301LN

steel samples and shrinkage of the phase in the AISI 316L steel samples.

The more the thickness was reduced, the greater the amount of α’, and the

superior the hardening of . This hardening is responsible for modifying its

mechanical properties, increasing its resistance, flow stress, hardness and

fragility, reducing the malleability, ductility, as well as making the material

very vulnerable to corrosion due to the formation of pit particles.

2. For the AISI 301LN steel, the typical morphology of the α’ phase acquired

by a scanning electronic microscope was of rips that are made up of big

plaques. Optic microscope and scanning electronic microscope reveled that

these plaques change their arrangement according to the deformation level.

3. For the AISI 316LA steel, the higher the level of deformation, the more

easily the deformed structure of the phase could be seen.

ACKNOWLEDGEMENTS

To the Brazilian companies METROFOR and PETROBRAS for supplying the

steel for this study.

The authors would also like to thank the Brazilian research agencies: CNPq –

Conselho Nacional de Desenvolvimento Científico e Tecnológico (National Counsel of

Technological and Scientific Development), FINEP – Financiadora de Estudos e

Projetos (Research and Projects Financing) and CAPES – Coordenação de

Aperfeiçoamento de Pessoal de Nível Superior (Coordination for the Improvement of

People with Higher Education) for their financial support.

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FIGURE CAPTIONS

Figure 1: Schematic representation of the pilot laminator used: a bench and duo type,

without reversion, and with cylinders of Ø43.5x107 mm. 

Figure 2: Optic Micrography of a) AISI 301LN, b) AISI 316L (magnification of 500X),

and c) AISI 301LN steel (magnification of 200X).

Figure 3: Optic Micrography of AISI 316L with deformation of 0.64 (magnification of

500X).

Figure 4: Micrography of sample of AISI 301LN with deformation of a) 0.31, and b)

0.64 (magnification of 1000X).

Figure 5: Micrography of sample of AISI 316L with deformation of a) 0.31, and b) 0.64

(magnification of 1000X).

Figure 6: Micrography obtained by SEM in the SE mode of sample a) AISI 301LN, and

sample b) AISI 316L with deformation of 0.64 using BSE mode.

Figure 7: Micrography of sample a) AISI 301LN deformed with 0.31, and b) 0.64,

obtained by SEM on BSE and SE modes.

Figure 8: Micrography of sample a) AISI 316L in the as received condition, and

deformation b) 0.31, obtained by SEM with BSE and SE modes , respectively.

Figure 9: Micrography with a) likeness to needles geometry, and b) laths, obtained from

AFM for samples of AISI 301 LN on height and attrition modes.

Figure 10: AFM micrography of AISI 301LN sample a) with deformation of 0.31 on

height and attrition modes, b) detail of the outstanding region (in red) on height mode,

and c) image of the outstanding region from probe monitor.

Figure 11: AFM micrography of AISI 301LN sample a) with deformation of 0.64 on

height and attrition modes, b) sample of AISI 316L on height and attrition mode, and c)

with deformation of 0.31 on deflection mode, and d) the same region on attrition and

height modes.

Figure 12: AFM micrography of AISI 316L sample a) with deformation of 0.64 on

deflection and attrition modes, b) on height and attrition modes of another region of the

sample, and c) image of this region from the probe monitor.

TABLE CAPTIONS

Table 1: Nominal chemical composition of AISI 301LN and 316L sheets ((*) EDS and

(**) coulometry).

Table 2: Roll conditions, thicknesses, deformation, and deformation rate.

Table 3: Thickness, volumetric fraction, standard deviation and crystalline domain (D)

for AISI 301LN and 316L steels.

FIGURES 

Figure 1 

Figure 2a 

Figure 2b 

Figure 2c 

Figure 3 

 

Figure 4a 

 

Figure 4b 

 

Figure 5a 

 

Figure 5b 

 

Figure 6a 

 

Figure 6b 

 

Figure 7a 

 

Figure 7b 

 

 

Figure 8a 

 

 

Figure 8b 

 

Figure 9a 

 

Figure 9b 

 

Figure 10a 

 

Figure 10b 

 

Figure 10c 

 

Figure 11a 

 

Figure 11b 

 

Figure 11c 

 

Figure 12a 

 

Figure 12b 

 

Figure 12c 

TABLES 

 

Table 1 

Element AISI 301LN

(wt. %) 

AISI 316L

(wt. %) 

C 0.039  0.023 

Cr(*)  17.91 16.53

Ni(*)  6.53 9.97

Mn  1.80 1.72

Si  0.79 0.62

S  0.015 0.015

P  0.045 0.048

Mo(*)  0.17 2.68

N(**)  0.10 0.04

Cu  0.18 0.12

Sn  0.015 0.023

Nb  0.025 0.035

V  0.032 0.038

Al  0.017 0.016

As  0.020 0.020

Table 2 

Roll 

Passes 

Roll 

Condition 

Initial 

Thickness 

[mm] 

Final Thickness 

[mm] 

Deformation  Deformation 

Rate 

[10‐2/s] 

1  1/2  1.90  1.80 0.05 1.80

2  1/2  1.80  1.70 0.06 1.90

3  1/2  1.70  1.60 0.06 2.02

4  1/2  1.60  1.50 0.06 2.15

5  1/2  1.50  1.40 0.07 2.30

6  2  1.40  1.30 0.07 2.47

7  2  1.30  1.20 0.08 2.67

8  2  1.20  1.10 0.09 2.90

9  2  1.10  1.00 0.10 3.12

 

Table 3 

Material 

AISI State 

Thickness 

[mm] 

Volumetric 

Fraction [%] 

(phase) 

Standard 

Deviation 

[%] 

D [nm] 

(phase) 

301LN 

Initial  1.9  80.1 (’) 8.78  0.19 (’) 

26% thickness 

reduction (0.31 of 

deformation) 

1.4  81.2 (’) 6.15  0.17 (’) 

47% thickness 

reduction (0.64 of 

deformation) 

1.0  94.9 (’) 1.78  0.17 (’) 

316L 

Initial  1.9  3.34 () 0.74  ‐ 

26% thickness 

reduction (0.31 of 

deformation) 

1.4  4.15 () 1.05  0.32 () 

47% thickness 

reduction (0.64 of 

deformation) 

1.0  2.16 () 0.60  0.10 ()