scholarly journals Microstructure, Strength, and Fracture Topography Relations in AISI 316L Stainless Steel, as Seen through a Fractal Approach and the Hall-Petch Law

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Oswaldo Antonio Hilders ◽  
Naddord Zambrano ◽  
Ramón Caballero
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Fractal Dimension ◽  
Fracture Surface ◽  
Surface Irregularity ◽  
Aisi 316L ◽  
Fractal Approach ◽  
Fracture Surface Roughness ◽  
Fracture Topography ◽  
316L Steel

The influence of the fracture surface fractal dimension DF and the fractal dimension of grain microstructure DM on the strength of AISI 316L type austenitic stainless steel through the Hall-Petch relation has been studied. The change in complexity experimented by the net of grains, as measured by DM, is translated into the respective fracture surface irregularity through DF, in such a way that the higher the grain size (lower DM values) the lower the fracture surface roughness (lower values of DF) and the shallower the dimples on the fractured surfaces. The material was heat-treated at 904, 1010, 1095, and 1194°C, in order to develop equiaxed grain microstructures and then fractured by tension at room temperature. The fracture surfaces were analyzed with a scanning electron microscope, DF was determined using the slit-island method, and the values of DM were taken from the literature. The relation between grain size, DM, mechanical properties, and DF, developed for AISI 316L steel, could be generalized and therefore applied to most of the common micrograined metal alloys currently used in many key engineering areas.

Microstructural Fractal Dimension of AISI 316L Steel

1994 ◽  
Vol 367 ◽  
Author(s):  
M. Hinojosa ◽  
R. Rodréguez ◽  
U. Ortiz
Keyword(s):  
Fractal Dimension ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Tensile Strain ◽  
Optical Microscope ◽  
Standard Test ◽  
Test Method ◽  
Aisi 316L ◽  
316L Steel ◽  
Deformation Processes

AbstractFractal dimension of the microstructure of AISI 316L steel (17 Cr, 12.7 Ni, 2.1 Mo, 1. 5 Mn, 0.01 C) with different degrees of strain were obtained from Richardson plots of grain boundary perimeter against magnification. Grain boundaries were revealed using conventional metallographic techniques and measurements were taken with the aid of an automatic image analizer (Quantimet 520) attached to an optical microscope. The magnifications used were 50, 100, 200, 400, and 1000X. The samples were obtained from a 4” diameter tubing, machined according to ASTM A370 standard test method and deformed to 5, 10, 15, and 20 % tensile strain. The results show that the fractal dimension of the grain boundaries changes as deformation is imparted to the material.These results suggest that fractal dimension may be used to describe microstructural evolution of metals during deformation processes.

scholarly journals Improving the Corrosion Resistance of AISI 316L Steel for Semiconductor Piping by Controlled Delta-Ferrite Content

2022 ◽  
Vol 60 (1) ◽  
pp. 46-52
Author(s):  
Young Woo Seo ◽  
Chan Yang Kim ◽  
Bo Kyung Seo ◽  
Won Sub Chung
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
316L Stainless Steel ◽  
Sem Analysis ◽  
Ferrite Content ◽  
Aisi 316L ◽  
Delta Ferrite ◽  
Aisi 316L Stainless Steel ◽  
316L Steel ◽  
The Difference

This study evaluated changes in delta-ferrite content depending on the preheating of AISI 316L stainless steel. We also determined the reasons for the variation in delta-ferrite content, which affects corrosion resistance. Changes in delta-ferrite content after preheating was confirmed using a Feritscope, and the microstructure was analyzed using optical microscopy (OM). We found that the delta-ferrite microstructure size decreased when preheating time was increased at 1295 oC, and that the delta-ferrite content could be controlled through preheating. Potentiodynamic polarization test were carried out in NaCl (0.5 M) + H2SO4 (0.5 M) solution, and it was found that higher delta-ferrite content resulted in less corrosion potential and passive potential. To determine the cause, an analysis was conducted using energy-dispersive spectroscopy (EDS), which confirmed that higher delta-ferrite content led to weaker corrosion resistance, due to Cr degradation at the delta-ferrite and austenite boundaries. The degradation of Cr on the boundaries between austenite and delta-ferrite can be explained by the difference in the diffusion coefficient of Cr in the ferrite and austenite. A scanning electron microscopy (SEM) analysis of material used for actual semiconductor piping confirmed that corrosion begins at the delta-ferrite and austenite boundaries. These results confirm the need to control delta-ferrite content in AISI 316L stainless steel used for semiconductor piping.

Test to Characterize the Machining Strength Property for the AISI 316L Steel

2011 ◽  
Vol 138-139 ◽  
pp. 604-611 ◽  
Author(s):  
Nivaldo Lemos Coppini ◽  
Julio Cesar Dutra ◽  
Elesandro Antonio Baptista ◽  
Fernando Aparecido Pacheco Da Silva Fortunato ◽  
Francisco Augusto Alves Ferreira ◽  
...  
Keyword(s):  
Grain Size ◽  
Ternary Phase ◽  
Ternary Phase Diagram ◽  
Aisi 316L ◽  
Large Plastic Deformation ◽  
Ni Alloy ◽  
Pile Up ◽  
316L Steel ◽  
The One ◽  
Diagram Analysis

This paper explores the effect of grain size on machining strength in an Fe-Cr-Ni alloy (AISI 316L). Ideal grain growth law [1], was used to obtain the activation energy level for this steel, which was 185 kJ.mol-1[2]. The initial grain size was measured (12 μm) and considering these values, both temperature and time values needed to achieve a final grain size ten times larger than the initial one, could be calculated, which were 1200°C and 2 hours. Ternary phase diagram analysis showed that austenite was stable at this temperature. Following, samples of 200 mm length were annealed and quenched in water to prevent any formation of sigma (μ) phase. Annealed and as-received bars were then used to compare their machining strength. Results showed that the machining strength is higher in the as received condition than the one after annealing (127 μm). It may be concluded that the bigger the grain size, the lower its machining strength. It is believed that this is caused by the pile-up of dislocations on grain boundaries, since this material exhibits large plastic deformation before fracture.

Effects of Aged Conditions on the Fracture Surface Fractal Dimension and Mechanical Behavior of an Austenitic Stainless Steel

2000 ◽  
Vol 6 (S2) ◽  
pp. 768-769
Author(s):  
O. A. Hilders ◽  
A. Quintero ◽  
L. Berrio ◽  
R. Caballero ◽  
L. Sáenz ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Fractal Dimension ◽  
Fractal Geometry ◽  
Fracture Behavior ◽  
Main Part ◽  
Room Temperature ◽  
Fracture Topography ◽  
Type Stainless Steel ◽  
Strength And Ductility

There have been several attempts to find a relation between the fractal morphology of the fracture surfaces and the mechanical properties of engineering materials., although the current resuls are inconclusive. If there are correlations between the fractal dimension and such properties, this parameter could be very useful to predict them and to improve the resistance to fracture. The main part of the investigations concerned with the fractal geometry and fracture behavior concentrate on the relations between roughness and fracture toughness . In the present work, the effects of thermal aging at 850°C on the fracture topography developed during the rupture in tension at room temperature of a 304 type stainless steel and their relation with the strength and ductility, were studied using the fractal geometry approach.

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