High ductility of ultrafine-grained steel via phase transformation

2008 ◽  
Vol 23 (6) ◽  
pp. 1578-1586 ◽  
Author(s):  
S. Cheng ◽  
H. Choo ◽  
Y.H. Zhao ◽  
X-L. Wang ◽  
Y.T. Zhu ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Tensile Ductility ◽  
High Strength ◽  
Strain Rate Effect ◽  
Inhomogeneous Deformation ◽  
Ultrafine Grained ◽  
Structural Applications ◽  
Order Of Magnitude ◽  
Strength And Ductility ◽  
Ultrafine Grained Steel

There is often a tradeoff between strength and ductility, and the low ductility of ultrafine-grained (UFG) materials has been a major obstacle to their practical structural applications despite their high strength. In this study, we have achieved a ∼40% tensile ductility while increasing the yield strength of FeCrNiMn steel by an order of magnitude via grain refinement and deformation-induced martensitic phase transformation. The strain-rate effect on the inhomogeneous deformation behavior and phase transformation was studied in detail.

Simultaneous Improvement of Ductility and Strength by Minute Doping in Ultrafine Grained Au Wires-Experiment and First Principle Study

2008 ◽  
Vol 1086 ◽  
Author(s):  
Yeong Huey Effie Chew ◽  
Chee Cheong Wong ◽  
Cristiano Ferraris ◽  
Hui Hui Kim
Keyword(s):  
High Strength ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
First Principle ◽  
Fine Grained ◽  
Preferential Segregation ◽  
Ultrafine Grained ◽  
Calcium Doping ◽  
Gold Wires ◽  
Strength And Ductility

AbstractAchieving both high strength and ductility is a common goal in the design of fine-grained materials. Here we report that with only ppm level of calcium doping, ductility and strength in ultrafine-grained gold wires can be concurrently improved by 108% and 65% respectively. Preferential segregation of calcium to stacking faults and grain boundaries in gold has reduced stacking fault energy of the system effectively, as shown by TEM and first principle simulation study. Through the modification of stacking fault energy, one can simultaneously increases the strength and ductility of a system.

High tensile ductility and high strength in ultrafine-grained low-carbon steel

2010 ◽  
Vol 527 (10-11) ◽  
pp. 2798-2801 ◽  
Author(s):  
T.S. Wang ◽  
Z. Li ◽  
B. Zhang ◽  
X.J. Zhang ◽  
J.M. Deng ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Tensile Ductility ◽  
Low Carbon Steel ◽  
High Strength ◽  
Low Carbon ◽  
Ultrafine Grained

Study of Machining-Induced Microstructure Variations of ECAE-Processed Ultrafine-Grained Copper

2009 ◽  
Author(s):  
Yong Huang ◽  
Mason Morehead
Keyword(s):  
Equal Channel Angular Extrusion ◽  
High Strength ◽  
Outer Radius ◽  
Precision Machining ◽  
Grain Sizes ◽  
Microstructure Stability ◽  
Ultrafine Grained ◽  
Structural Applications ◽  
Ultrafine Grained Materials ◽  
Stability Issues

Various methods for production of bulk ultrafine-grained (UFG)/nanostructured materials have been developed. Recently, a top-down approach named equal channel angular extrusion (ECAE), a form of severe plastic deformation (SPD), has gained increasing attention in making bulk UFG materials. Such bulk materials are favored for their high strength, wear resistance, ductility, and high strain-rate superplasticity, which makes them suitable for light weight engineering and medical applications. Further precision machining work is normally indispensable for structural applications after bulk ultrafine grained materials are manufactured from any SPD processes. Unfortunately, the microstructure stability issues in precision machining such materials are frequently ignored. Using an ECAE copper bar as an example, this study has investigated its machining-induced workpiece microstructure variation. It has been found that there was a small increase in the size parameter median and the average arithmetic and area weighted grain sizes when comparing those of machined and unmachined bars, and the measured grain sizes oscillated slightly in the radial direction of the machined bar. Dislocation density was shown to have the most reduction at the outer radius location of the machined ECAE bar where more heat and/or higher pressure were experienced.

High Strength Microscrew with Ultrafine Grained Structure

2014 ◽  
Vol 783-786 ◽  
pp. 2695-2700
Author(s):  
Shiro Torizuka ◽  
Eijiro Muramatsu
Keyword(s):  
Uniform Elongation ◽  
Steel Wire ◽  
High Strength ◽  
Tensile Tests ◽  
Low Carbon ◽  
Ultrafine Grained Structure ◽  
Bainitic Steels ◽  
Ultrafine Grained ◽  
Reduction In Area ◽  
Ultrafine Grained Steel

While uniform elongation is a measure of ductility of the material, reduction in area in tensile tests is also an important measure of ductility. It was found that the reduction in area - tensile strength balance is far better than the conventional ferrite+pearlite steels and even superior to martensitic and bainitic steels. Formability of ultrafine-grained steel is examined by applying to form a M1.7 micro screw using these ultrafine-grained steels. Screws are formed through the process of cold heading and rolling. Relationship between cold heading, rolling, uniform elongation and reduction in area are investigated to clarify the formability of ultrafine-grained steels. Low-carbon ultrafine-grained steel has excellent cold headability and favorable rolling properties, i.e., excellent formability. Reduction in area is a measure to determine formability on cold heading. Ultrafine grained steel wire with length of several hundred meter were developed with the technology of warm continuous multi-directional rolling. This wire also have a good formability which can form microscrews. High strength microscrew with ultrafine grained structure was obtained.

scholarly journals Tensile Deformation of Ultrafine-Grained Fe-Mn-Al-Ni-C Alloy Studied by In Situ Synchrotron Radiation X-ray Diffraction

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1115
Author(s):  
Si Gao ◽  
Takuma Yoshimura ◽  
Wenqi Mao ◽  
Yu Bai ◽  
Wu Gong ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Tensile Deformation ◽  
Tensile Ductility ◽  
High Strength ◽  
X Ray Diffraction ◽  
Premature Failure ◽  
X Ray ◽  
Intermetallic Particles ◽  
Ultrafine Grained

Intermetallic compounds are usually considered as deleterious phase in alloy designing and processing since their brittleness leads to poor ductility and premature failure during deformation of the alloys. However, several studies recently found that some alloys containing large amounts of NiAl-type intermetallic particles exhibited not only high strength but also good tensile ductility. To clarify the role of the intermetallic particles in the excellent tensile properties of such alloys, the tensile deformation behavior of an ultrafine-grained Fe-Mn-Al-Ni-C alloy containing austenite matrix and B2 intermetallic particles was investigated by using in situ synchrotron radiation X-ray diffraction in the present study. The elastic stress partitioning behavior of two constituent phases during tensile deformation were quantitively measured, and it was suggested that B2 particles played an important role in the high strength and large tensile ductility of the material.

Influence of Annealing on the Structure and Mechanical Properties of Ultrafine-Grained Alloy Ti-6Al-7Nb, Processed by Severe Plastic Deformation

2010 ◽  
Vol 667-669 ◽  
pp. 943-948 ◽  
Author(s):  
Veronika Polyakova ◽  
Irina P. Semenova ◽  
Ruslan Valiev
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Equal Channel Angular Pressing ◽  
Human Body ◽  
High Strength ◽  
Point Of View ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Strength And Ductility

This work is devoted to enhancement of strength and ductility of the Ti-6Al-7Nb ELI alloy, which is less harmful from medical point of view for human body in comparison to Ti-6Al-4V. It has been demonstrated that formation of an ultrafine-grained structure in the alloy with the help of equal-channel angular pressing in combination with heat and deformation treatments allows reaching high strength (UTS = 1400 MPa) and sufficient ductility (elongation 10 %).

scholarly journals High Strength and Ductility in Ball-Milled Titanium Powders Consolidated by High-Pressure Torsion

2010 ◽  
Vol 654-656 ◽  
pp. 1239-1242 ◽  
Author(s):  
Kaveh Edalati ◽  
Z. Horita ◽  
Hiroshi Fujiwara ◽  
Kei Ameyama ◽  
Masaki Tanaka ◽  
...  
Keyword(s):  
High Pressure ◽  
Ball Milling ◽  
High Pressure Torsion ◽  
High Strength ◽  
Ultrafine Grained Structure ◽  
Ultrafine Grained ◽  
Titanium Powders ◽  
Strength And Ductility

Pure Ti powders were subjected to ball milling and subsequently high-pressure torsion (HPT) for consolidation. It is found that a fully dense (99.9%) disc with ultrafine grained structure (~50-300 nm) was produced. The strength and ductility were well comparable to those of ball-milled Ti-6%Al-4%V powders after hot roll sintering.

Machinability Research and Workpiece Microstructure Characterization in Turning of Ultrafine Grained Copper

2005 ◽  
Author(s):  
Mason Morehead ◽  
Yong Huang
Keyword(s):  
Nanostructured Materials ◽  
Equal Channel Angular Extrusion ◽  
High Strength ◽  
Precision Machining ◽  
Top Down ◽  
Microstructure Stability ◽  
Ultrafine Grained ◽  
Structural Applications ◽  
Stability Issues ◽  
Tool Cutting

Various methods for production of bulk ultrafine grained/nanostructured materials have been developed. They can be classified into two categories based on their approaches: the bottom-up and top-down approaches. Recently, a top-down approach named equal channel angular extrusion (ECAE), a form of severe plastic deformation (SPD), has been gaining more and more attention in making bulk ultrafine grained/nanostructured materials. Such bulk materials are favored for there high strength, wear resistance, ductility, and high strain-rate superplasticity, which makes them suitable for light weight engineering and medical applications. Further precision machining work is normally indispensable for structural applications after bulk ultrafine grained/nanostructured materials are manufactured from any SPD processes. While researchers are increasingly interested in commercially producing SPD-processed bulk ultrafine grained/nanostructured materials and characterizing their chemical and physical properties, the machinability and microstructure stability issues in precision machining such materials are frequently ignored. Using an ECAE processed bulk ultrafine grained copper bar as an example, this study investigates the machinability as well as machining-induced workpiece microstructure variation of such ECAE processed materials in precision turning. Tool cutting performance in turning the ultrafine grained copper bar is also compared with that of the regular copper bar.

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