Effect of Thermomechanical Processing on Structure and Corrosion-Mechanical Properties of AISI 321 Steel

2010 ◽  
Vol 89-91 ◽  
pp. 769-772
Author(s):  
G.E. Kodzhaspirov ◽  
A.I. Rudskoy ◽  
V.V. Rybin
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Fine Structure ◽  
Dislocation Density ◽  
Mechanical Strength ◽  
Thermomechanical Processing ◽  
Test Procedure ◽  
Nacl Solution ◽  
Aisi 321 ◽  
Carbide Transformations

The effect of Thermomechanical Processing (TMP) on the fine structure (dislocation density and fragments evolution), recrystallization, carbide transformations and tendency toward intercrystalline corrosion (ICC) and corrosion-mechanical strength of AISI 321 type steels is described. It’s shown that the grain size and overall amount of carbide phase has almost no effect on ICC. With an increase in dislocation density a tendency is observed toward a reduction in corrosion rate, but increases with an increase in proportion of recrystallized material. This connection is explained by an increasing of the level of local microstresses, which may be arranged structurally in the form of partial disclinations and aggravate ICC. A new test procedure was developed for estimating the corrosion-mechanical strength of steel. It follows from the obtained data that the hot working with the following accelerate cooling under industrial conditions does not develop a tendency toward corrosion cracking in 3% agueous NaCl solution.

Effect of Thermomechanical Processing on Grain Size, Texture and Mechanical Properties of Pure Magnesium

2020 ◽  
Vol 985 ◽  
pp. 97-108
Author(s):  
Mouhamadou Moustapha Sarr ◽  
Motohiro Yuasa ◽  
Hiroyuki Miyamoto
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Yield Stress ◽  
Thermomechanical Processing ◽  
Pure Magnesium ◽  
Grain Structure ◽  
Misorientation Distribution ◽  
Processed Material ◽  
Texture Characterization

This study aims to investigate the effect of processing routes (A and Bc) and temperature on microstructure, texture and mechanical properties of pure magnesium was studied in this research. An extruded pure magnesium (~99,9 %) was subjected to severe plastic deformation (SPD) by ECAP. Deformation was conducted at 523K and 473K and two different processing routes (A and Bc) were used to control the texture. The microstructure and texture characterization of the pressed materials were carried out. It was found that the microstructure displayed a bimodal grain structure after two passes and then became homogeneous after four passes following both routes A and Bc. The misorientation distribution was examined and the results revealed that the fraction of high angle grain boundaries (HAGB) was higher at temperature 473K. The texture was randomized following route Bc whereas it became strengthened in route A after four passes. According to the Hall-Petch (HP) relationship, the yield stress of polycrystalline metals increases with a decrease in grain size. In this study, a positive slope k was achieved in the strengthened texture while a negative one was obtained in the softened texture. The ductility of ECAP processed material was considerably improved (from 23% to 38%) without sacrificing the yield stress by route Bc at 423K.

scholarly journals Influence of thermomechanical processing on the grain size, texture and mechanical properties of Mg-Al alloys

2012 ◽  
Vol 50 (01) ◽  
pp. 1-23
Author(s):  
B. SRINIVASARAO ◽  
J. A. DEL ◽  
O. A. RUANO ◽  
M. T. PÉREZ-PRADO
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Thermomechanical Processing ◽  
Al Alloys

Microstructure and Mechanical Properties of Mechanically Alloyed NiAl

1990 ◽  
Vol 213 ◽  
Author(s):  
S. J. Hwang ◽  
P. Nash ◽  
M. Dollar ◽  
S. Dymek
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Dislocation Density ◽  
Work Hardening ◽  
Room Temperature ◽  
Hot Extrusion ◽  
Homogeneous Distribution ◽  
Mechanically Alloyed ◽  
Oxide Particles ◽  
Temperature Work

ABSTRACTMechanical alloying (MA) has been used to produce NiAl powders from either elemental or prealloyed constituents. The powders were consolidated by hot extrusion resulting in material which was fully dense, with a grain size around 1 μm and a homogeneous distribution of oxide particles with sizes in the range 10 to 100 nm. TEM observation indicates the presence of a significant dislocation density after consolidation. Mechanical properties have been studied by compression testing from room temperature to 1300 K in air. Yield strengths ranged from 1453 MPa to 32 MPa depending on material and test temperature. Work hardening was observed at all test temperatures for both materials. Substantial ductility was observed even at room temperature where it exceeds 7.5 %. The effects of microstructure on the mechanical properties are discussed.

Effects of Heat Input Conditions on the Local Thermophysical Properties of Super Duplex Stainless Steels

2018 ◽  
Vol 930 ◽  
pp. 317-321
Author(s):  
José Adilson de Castro ◽  
Gláucio Soares da Fonseca ◽  
D.S.S. Almeida ◽  
L.C.R. Lopes ◽  
C.R. Xavier ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Mechanical Strength ◽  
Stainless Steels ◽  
Thermal History ◽  
Duplex Stainless Steels ◽  
Measured Temperature ◽  
Sem Images ◽  
Super Duplex Stainless Steels ◽  
Welding Procedure

The thermal properties of the super duplex stainless steels are strongly affected by the thermal history when welding procedure are applied leading to substantial changes on the mechanical properties of the welding region. The controlled dual phase microstructure (ferrite and austenite) guarantee excellent mechanical properties such as mechanical strength and corrosion resistance, in addition to small thermal expansion coefficient and high thermal conductivity. In this research a model able to predict the thermal history of the welding pieces coupled with local mechanical properties developed during welding procedure is developed. The model was verified by measured temperature profile and used to predict local properties such as grain size evolution, hardness and mechanical strength. An inverse method was implemented to obtain the parameters fitting for the grain growth evolution, hardness and yielding strength compatible with the final microstructure and grain size measured using SEM images and stereological techniques.

Effects of Annealing on Mechanical Properties in Ultrafine-Grained Cu–Al Alloy

2012 ◽  
Vol 581-582 ◽  
pp. 363-367 ◽  
Author(s):  
Yan Long ◽  
Yu Lan Gong ◽  
Shi Ying Ren ◽  
Xiao Xiang Wu ◽  
Xin Kun Zhu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Dislocation Density ◽  
Ambient Temperature ◽  
Rolling Reduction ◽  
Al Alloy ◽  
Twin Density ◽  
Ultrafine Grained ◽  
Before And After ◽  
Main Effects

Abstract. The mechanical properties and microstructure of an ultrafine-grained Cu–Al alloy before and after annealing are investigated. Ultrafine-grained Cu–Al alloy samples are processed by means of rolling at ambient temperature and rolling reduction exceeds 90%. It is found that the strength of ultrafine-grained Cu–Al alloy increased rather than decreased after annealing for 1 h in the temperature range between150°Cand 300°C.Based on the microstructures observation of samples, it can be known that both the grain size and dislocation density have main effects on hardening of ultrafine-grained Cu–Al alloy which result from annealing. These investigations showed that the annealing hardening effect can be explained by the change of dislocation density and twin density.

Dislocation study of ARMCO iron processed by ECAP

2016 ◽  
Vol 1818 ◽  
Author(s):  
Jairo Alberto Muñoz ◽  
Oscar Fabián Higuera ◽  
José María Cabrera
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Dislocation Density ◽  
Deformation Behavior ◽  
Armco Iron ◽  
Tensile Tests ◽  
Grain Sizes ◽  
Angular Pressing ◽  
Cylindrical Samples

ABSTRACTThe aim of this work was to study the deformation behavior of an Armco iron after severe plastic deformation by equal channel angular pressing (ECAP). Particular attention was paid to predict the dislocation density by different approaches like the model proposed by Bergström. Experimental measures of dislocation density by different techniques are used in the discussion. Cylindrical samples of ARMCO iron (8mm of diameter, 60mm of length) were subjected to ECAP deformation using a die with an intersecting channel of Φ=90° and outer arc of curvature of ψ= 37° die. Samples were deformed for up to 16 ECAP passes following route Bc. The mechanical properties of the material were measured after each pass by tensile tests. The original grain size of the annealed iron (70 μm) was drastically reduced after ECAP reaching grain sizes close to 300nm after 16 passes.

Effects of Heat Treatments on Tungsten for Armours in NFR

2014 ◽  
Vol 783-786 ◽  
pp. 2353-2358 ◽  
Author(s):  
Laura Ciambella ◽  
Riccardo Donnini ◽  
Roberto Montanari
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Dislocation Density ◽  
Heat Treatments ◽  
Original Material ◽  
Plasma Facing Components ◽  
Hardness Tests ◽  
Heat Treated ◽  
Average Grain Size ◽  
Fusion Applications

Tungsten is a promising armour material for plasma facing components of nuclear fusion reactors (NFR) because of its low sputtering rate and favourable thermo-mechanical properties (high melting point and good thermal conductivity). This paper reports some results of an experimental campaign carried out for investigating the microstructural characteristics and the mechanical properties of tungsten (99.97% purity; 5% porosity) for fusion applications. Tungsten has been heat treated at 500 °C and 800 °C with increasing soaking time. The samples in as-supplied condition and after each step of the heat treatments have been examined by optical microscopy and TEM observations, X-ray diffraction (XRD) and micro-hardness tests. The original material has a dislocation density of 1.5 x 1010 cm-2 and a mean grain size of 65 μm. Grain size is not affected by the heat treatment at 500 °C which induces only a weak decrease of dislocation density leading to a little smaller hardness. The microstructure can be considered substantially stable even if a weak recovery of dislocations takes place. On the contrary, grain growth is observed after heating at 800 °C: 10 hours of treatment nearly doubles the average grain size.

Optimization of Strength and Ductility in Ultra-Fine 304 Stainless Steel after Equal-Channel Angular Processing

2010 ◽  
Vol 667-669 ◽  
pp. 937-942 ◽  
Author(s):  
Z.J. Zheng ◽  
Yan Gao ◽  
Y. Gui ◽  
M. Zhu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Dislocation Density ◽  
Vickers Hardness ◽  
304 Stainless Steel ◽  
Angular Pressing ◽  
Equal Channel Angular Processing ◽  
Strength And Ductility

The microstructure and mechanical properties of 304 stainless steel were investigated which was subjected to equal channel angular pressing (ECAP). Tensile strength, elongation, Vickers hardness of as-ECAPed and annealed ECAPed 304 stainless steel were systematically measured and compared and microstructure evolution during ECAP and ECAP+annealing was observed by OM and TEM. It was found that with the increasing of ECAP passes, the grain size of stainless steel was effectively refined to nanoscale, such as about 50 nm after 8 ECAP-passes. In addition, the dislocation density in ECAPed samplel increased greatly, consequently, the tensile strength and hardness of ECAPed 304 stainless steel increased and elongation decreased remarkably. After annealing at 600°C for 10 min，the ductility of ECAPed stainless steel was improved greatly while grains did not have obvious growth, and strength did not change much. The above results showed that the optimization of strength and ductility in ultra-fined 304 stainless steel can be achieved by appropriate ECAP plus annealing processes.

Strengthening Mechanisms in Low Carbon Lath Martensite as Influenced by Austenite Conditioning

2018 ◽  
Vol 941 ◽  
pp. 574-582
Author(s):  
S.C. Kennett ◽  
George Krauss ◽  
Kip O. Findley
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Prior Austenite ◽  
Thermomechanical Processing ◽  
Lath Martensite ◽  
Weight Percent ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Prior Austenite Grain

Low carbon lath martensitic microstructures are used in various steel products requiring high strength and toughness. These microstructures are conventionally produced through re-austenitizing and quenching followed by low or high temperature tempering. It is also possible to produce lath martensite through direct quenching immediately following thermomechanical processing. In this study, deformation below the austenite recrystallization temperature before quenching to form martensite was simulated through laboratory scale Gleeble processing of a 0.2 weight percent carbon ASTM A514 steel microalloyed with up to 0.21 weight percent niobium. Thermomechanical processing generally increases the dislocation density of the as-quenched martensite, which is sensitive to the austenite grain size before thermomechanical processing. The hardness of the thermomechanically-processed steels is generally greater than steels austenitized at comparable temperatures without deformation; this hardness difference is attributed to the increase in dislocation density and increased lath misorientation in the thermomechanically-processed conditions. The hardness is generally independent of prior austenite grain size for the thermomechanically processed conditions in contrast to conventionally austenitized and quenched conditions, which have a Hall-Petch correlation with austenite grain size. The strength increase of the thermomechanically processed conditions compared to the conventionally austenitized and quenched conditions is maintained after tempering. However, there is a larger drop in strength for small prior austenite grain sizes for both conventionally austenitized and quenched and thermomechanically processed steels. Overall, the strength of these lath martensitic steels can be directly related to dislocation density through a Taylor hardening model.

scholarly journals Analysis on the Manufacturing of an AA5083 Straight Blade Previously ECAE Processed

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Daniel Salcedo ◽  
Carmelo Luis ◽  
Ignacio Puertas ◽  
Javier León ◽  
Juan Pablo Fuertes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
Mechanical Strength ◽  
Research Work ◽  
Straight Blade ◽  
Processed Material ◽  
Properties Of Materials ◽  
Mechanical Components

Over these past few years, there have been a large number of technical papers published related to the problem of improving the mechanical properties of materials obtained through severe plastic deformation. Nevertheless, the number of technical papers dealing with improvement in the mechanical properties of mechanical components manufactured from submicrometric grain size material has not been so proficient. Therefore, in this present research work, a straight blade has been manufactured starting from AA-5083 previously processed by ECAE twice (N2) with route C. This material will be manipulated so as to be isothermally forged at different temperature values. This present research work shows the results that are inherent in an improvement in the mechanical properties and the microstructure achieved in the thus obtained components, compared with the starting material. In addition, the optimum forging temperature to achieve these components will be determined. As shown in this research work, it is possible to obtain submicrometric grain size mechanical components with a higher mechanical strength than those obtained in nonultrafine grained materials. The originality of this research work lies in the manufacturing of actual mechanical components from ECAE processed material and the analysis of their properties.

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