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Nano-subgrain Strengthening in Ball-milled Iron

Description: The strength and deformation behavior of ball-milled, iron-base materials containing nano-scale subgrains have been evaluated. As reported by several authors, nanosubgrains form during the early stages of ball milling as a result of severe plastic deformation inherent in the ball milling process. The strength for these nano-scale subgrains are compared with the strength of larger-scale subgrains in iron and iron-base alloys produced by traditional mechanical working. The data covers over 2 orde… more
Date: March 23, 2006
Creator: Lesuer, D R; Syn, C K & Sherby, O D
Partner: UNT Libraries Government Documents Department
open access

Laminated metal composites of ultrahigh carbon steel/brass and Al/Al-SiC: Processing and properties

Description: We have fabricated laminated metal composites of (i) ultrahigh carbon steel (1.8%C) and brass (70Cu-30Zn), and (ii) aluminum 5182 and aluminum 6061 with 25 vol.% SiC{sub p}. The laminates were prepared by hot pressing alternating layers of the component materials in an argon gas atmosphere. The steel was thermo-mechanically processed to produce a fine grained microstructure that exhibited superplasticity. The brass and aluminum materials were obtained from commercial sources and used in the as-… more
Date: October 1, 1991
Creator: Syn, C. K.; Lesuer, D. R.; Cadwell, K. L.; Sherby, O. D. & Brown, K. R.
Partner: UNT Libraries Government Documents Department
open access

Overview on superplasticity research on small-grained materials

Description: Superplasticity is generally associated with fine grains, grain boundary sliding, and high tensile ductility at elevated temperature. This paper reviews some of the recent important findings in fine-grained superplasticity, including the areas of superplastic ceramics and bf-high-strain-rate superplasticity (HSRS). Deformation mechanism maps are shown to be powerful tools for predicting the conditions where HSRS can be expected. Ultrafine grained materials, processed economically, remain an imp… more
Date: July 1, 1994
Creator: Sherby, O. D.; Nieh, T. G. & Wadsworth, J.
Partner: UNT Libraries Government Documents Department
open access

An Analysis of Gas Pressure Forming of Superplastic AL 5083 Alloy

Description: Al 5083 disks of a superplastic forming grade were gas-pressure formed to hemispheres and cones at constant forming pressures with and without back pressure. The forming operation was performed using an in-house designed and built biaxial forming apparatus. The temporal change of dome heights of the hemispheres and cones were measured for the different forming and back pressures applied. The flow stresses and strain rates developed at the top of the dome during the forming step were shown to cl… more
Date: May 4, 2001
Creator: Syn, C K; O'Brien, M J; Lesuer, D R & Sherby, O D
Partner: UNT Libraries Government Documents Department
open access

Denuded Zones, Diffusional Creep, and Grain Boundary Sliding

Description: The appearance of denuded zones following low stress creep in particle-containing crystalline materials is both a microstructural prediction and observation often cited as irrefutable evidence for the Nabarro-Herring mechanism of diffusional creep. The denuded zones are predicted to be at grain boundaries that are orthogonal to the direction of the applied stress. Furthermore, their dimensions should account for the accumulated plastic flow. In the present paper, the evidence for such denuded z… more
Date: June 27, 2001
Creator: Wadsworth, J; Ruano, O A & Sherby, O D
Partner: UNT Libraries Government Documents Department
open access

Mechanical and Thermal Properties of Ultra-High Carbon Steel Containing Aluminum

Description: The properties of ultrahigh carbon steels (UHCS) are strongly influenced by aluminum additions. Hardness studies of quenched UHCS-Al alloys reveal that the temperature for the start of transformation increases with increases in aluminum content. It is shown that this change is a function of the atomic percent of solute and of the valence state when comparisons are made with UHCSs containing silicon and tin as solutes. The thermal expansion of UHCSs with dilute aluminum additions shows no discon… more
Date: January 31, 2006
Creator: Syn, C K; Lesuer, D R; Goldberg, A; Tsai, H & Sherby, O D
Partner: UNT Libraries Government Documents Department
open access

MICROSTRUCTURE IN ADIABATIC SHEAR BANDS IN A PEARLITIC ULTRAHIGH CARBON STEEL

Description: Adiabatic shear bands, obtained in compression deformation at a strain rate of 4000 s{sup -1}, in a pearlitic 1.3%C steel, were investigated. Shear-bands initiated at 55% compression deformation with the width of the band equal to 14 {micro}m. Nano-indentor hardness of the shear band was 11.5 GPa in contrast to the initial matrix hardness of 3.5 GPa. The high strength of the shear band is attributed to its creation from two sequential events. First, large strain deformation, at a high strain ra… more
Date: September 22, 2003
Creator: Syn, C K; Lesuer, D R & Sherby, O D
Partner: UNT Libraries Government Documents Department
open access

Plastic flow and strength of uranium and its alloys

Description: The mechanical behavior of uranium and its alloys is reviewed with special emphasis on plastic flow behavior of polycrystalline materials. The strength of uranium is influenced by crystal structure as well as by point, planar, and volume defects; wit these factors in mind, texture hardening, strain hardening, solute hardening, grain and subgrain size hardening, and precipitation and particle hardening are discussed. Temperature and strain rate influence the various strengthening mechanisms in d… more
Date: January 28, 1974
Creator: Sherby, O. D.; Bly, D. L. & Wood, D. H.
Partner: UNT Libraries Government Documents Department
open access

An Evaluation of Power Law Breakdown in Metals, Alloys, Dispersion Hardened Materials and Compounds

Description: Creep at high stresses often produces strain rates that exceed those that would be predicted by a power law relationship. In this paper, we examine available high stress creep data for pure metals, solid solution alloys, dispersion strengthened powder metallurgy materials and compounds for power law breakdown (PLB). The results show that, if PLB is observed, then the onset of PLB is generally observed at about {epsilon}/D{sub eff} = 10{sup 13} m{sup -2}, where D{sub eff} is the effective diffus… more
Date: October 20, 1999
Creator: Lesuer, D. R.; Syn, C. K. & Sherby, O. D.
Partner: UNT Libraries Government Documents Department
open access

Influence of volume fraction of component materials and interlayer bond strength on fracture toughness of multi-layer Al 6090-25 vol % SiCp and Al 5182 laminates

Description: Multilayer laminates of Al 6090/SiC/25p MMC and Al 5182 were prepared by hot pressing alternating layers of the component materials at 450{degree}C in an argon gas atmosphere. Tensile properties, interlayer normal and shear bond strengths, and fracture toughness were measured in the T6-treated and untreated conditions. Fracture toughness was also measured as a function of the volume fraction of the MMC component. Yield and tensile strengths increased substantially by the T6 treatment while the … more
Date: November 1, 1993
Creator: Syn, C. K.; Stoner, S.; Lesuer, D. R. & Sherby, O. D.
Partner: UNT Libraries Government Documents Department
open access

Modeling the Evolution of Strength During Wire Drawing

Description: Extensive plastic deformation during wire drawing is commonly used to produce steel wires with very high strengths. Typically these steels are eutectoid and hypereutectoid steels and drawing strains up to 4 are used during processing. The resulting materials can have tensile strengths in excess of 4000 MPa. The evolution of microstructure and the strengthening mechanisms resulting from wire drawing have been studied for eutectoid and hypereutectoid steels. Strength has been shown to be a functi… more
Date: August 5, 2002
Creator: Lesuer, D R; Syn, C K & Sherby, O D
Partner: UNT Libraries Government Documents Department
open access

High temperature, high strain rate extrusion of ultrahigh-carbon steels

Description: It is shown that high rate extrusion is a viable production process for obtaining desirable microstructures and mechanical properties in ultrahigh carbon steels (UHCSs). The coefficient of friction for extrusion was determined for the UHCSs as well as five other materials and shown to be a function of stress--decreasing with increasing stress. The extruded UHCSs deform by a diffusion-controlled dislocation creep process. Stacking fault energies have been calculated from the extrusion data and o… more
Date: August 23, 2000
Creator: Lesuer, D R; Syn, C K & Sherby, O D
Partner: UNT Libraries Government Documents Department
open access

Deformation and Shear Band Development in an Ultrahigh Carbon Steel During High Strain Rate Deformation

Description: The mechanical response of a pearlitic UHCS-1.3C steel deformed at approximately 4000 s{sup -1} to large strains ({var_epsilon} = -0.9) has been studied. Failure, at both the macroscopic and the microscopic levels has been evaluated, and the ability of the material to absorb energy in compression has been examined. Failure occurred by the development of a shear band. However before failure, extensive buckling of the carbide plates was observed and the UHCS-1.3C material exhibited significant po… more
Date: July 6, 2004
Creator: Lesuer, D R; Syn, C K & Sherby, O D
Partner: UNT Libraries Government Documents Department
open access

Stress-Strain Rate Relations in Ultra High Carbon Steels Deformed in the Ferrite Range of Temperature

Description: The stress-strain rate relations in ultrahigh carbon steels (UHCSs) have been analyzed at high temperatures in the ferrite range where dislocation slip is the principal deformation mechanism. Specifically, the present investigation centers on the factors influencing the strength of UHCS in the ferrite range of 500 to 700 C and in the strain rate range of 10{sup -3} to 10{sup 3} s{sup -1}. These steels contain iron carbide as a second phase either in the form of spheroidite or pearlite and vary … more
Date: February 20, 2003
Creator: Syn, C K; Lesuer, D R; Sherby, O D & Taleff, E M
Partner: UNT Libraries Government Documents Department
open access

Processing and mechanical properties of laminated metal composites of Al 6090-25 vol % SiC{sub p} and Al 5182

Description: Multi-layer laminate metal composites (LMCs) containing equal volume percent of Al 5182 and Al 6090--25 Vol.% SiC{sub p} were made. The laminates were prepared by hot pressing alternate layers to a fourth of initial height at 450C in argon gas atmosphere. Some laminates were warm rolled by repeatedly heating to 450C and rolling. The large plastic deformation ensured good bonding between layers. Tensile properties, fracture toughness, and damping capacity of these deformation-bonded laminates we… more
Date: March 19, 1993
Creator: Syn, C. K.; Lesuer, D. R. & Sherby, O. D.
Partner: UNT Libraries Government Documents Department
open access

Mechanical and Thermal Properties of Ultra-High Carbon Steel Containing Aluminum

Description: The properties of ultrahigh carbon steels (UHCS) are strongly influenced by aluminum additions. Hardness studies of quenched UHCS-Al alloys reveal that the temperature for the start of transformation increases with increases in aluminum content. It is shown that this change is a function of the atomic percent of solute and of the valence state when comparisons are made with UHCSs containing silicon and tin as solutes. The thermal expansion of UHCSs with dilute aluminum additions shows no discon… more
Date: October 3, 2005
Creator: Syn, C. K.; Lesuer, D. R.; Goldberg, A.; Tsai, H. C. & Sherby, O. D.
Partner: UNT Libraries Government Documents Department
open access

Influence of Iron Oxide Particles on the Strength of Ball-Milled Iron

Description: Detailed microstructural and mechanical property studies of ball-milled iron, in the powder and consolidated states, are reviewed and assessed. The analyses cover three and one-half orders of magnitude of grain size (from 6 nm to 20 mm) and focus on the influence of oxide particles on the strength. The study includes the early work of Koch and Yang, Kimura and Takaki and continues with the more recent work of Umemoto et al and Belyakov, Sakai et al. It is shown that the major contributors to st… more
Date: December 7, 2005
Creator: Lesuer, D R; Syn, C K & Sherby, O D
Partner: UNT Libraries Government Documents Department
open access

Thermo-Mechanical Processing and Properties of a Ductile Iron

Description: Thermo-mechanical processing of ductile irons is a potential method for enhancing their mechanical properties. A ductile cast iron containing 3.6% C, 2.6% Si and 0.045% Mg was continuously hot-and-warm rolled or one-step press-forged from a temperature in the austenite range (900{degrees}C-1100{degrees}C) to a temperature below the A, temperature. Various amounts of reduction were used (from 60% to more than 90%) followed by a short heat ent at 600`C. The heat ent lead to a structure of fine gr… more
Date: July 14, 1997
Creator: Syn, C. K.; Lesuer, R. R. & Sherby, O. D.
Partner: UNT Libraries Government Documents Department
open access

Processing and mechanical behavior of hypereutectoid steel wires

Description: Hypereutectoid steels have the potential for dramatically increasing the strength of wire used in tire cord and in other high strength wire applications. The basis for this possible breakthrough is the elimination of a brittle proeutectoid network that can form along grain boundaries if appropriate processing procedures and alloy additions are used. A review is made of work done by Japanese and other researchers on eutectoid and mildly hypereutectoid wires. A linear extrapolation of the tensile… more
Date: June 25, 1996
Creator: Lesuer, D. R.; Syn, C. K.; Sherby, O. D. & Kim, D. K.
Partner: UNT Libraries Government Documents Department
open access

History of ultrahigh carbon steels

Description: The history and development of ultrahigh carbon steels (i.e., steels containing between 1 and 2.l percent C and now known as UHCS) are described. The early use of steel compositions containing carbon contents above the eutectoid level is found in ancient weapons from around the world. For example, both Damascus and Japanese sword steels are hypereutectoid steels. Their manufacture and processing is of interest in understanding the role of carbon content in the development of modern steels. Alth… more
Date: June 20, 1997
Creator: Wadsworth, J. & Sherby, O. D.
Partner: UNT Libraries Government Documents Department
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Laminated metals composites fracture and ballistic impact behavior

Description: Recent advances in the fracture and ballistic impact response of laminated metal composites (LMCs) are reviewed. The laminate structure can provide significant improvements to these properties relative to the component materials. Typical fracture and ballistic impact properties in LMCs are illustrated for systems containing Al alloys and Al matrix composites. The unique mechanisms operating in a layered structure that contribute to fracture or ballistic impact resistance are discussed. The infl… more
Date: January 20, 1998
Creator: Lesuer, D. R.; Syn, C. K.; Sherby, O. D. & Wadsworth, J.
Partner: UNT Libraries Government Documents Department
open access

Ancient Blacksmiths, The Iron Age, Damascus Steels, and Modern Metallurgy

Description: The history of iron and Damascus steels is described through the eyes of ancient blacksmiths. For example, evidence is presented that questions why the Iron Age could not have begun at about the same time as the early Bronze Age (i.e. approximately 7000 B.C.). It is also clear that ancient blacksmiths had enough information from their forging work, together with their observation of color changes during heating and their estimate of hardness by scratch tests, to have determined some key parts o… more
Date: September 11, 2000
Creator: Sherby, O. D. & Wadsworth, J.
Partner: UNT Libraries Government Documents Department
open access

Ultrahigh carbon steel for automotive applications

Description: Ultrahigh carbon steels (UHCSs), which contain 1--2.1% carbon, have remarkable structural properties for automotive application when processed to achieve fine ferrite grains with fine spheroidized carbides. When processed for high room temperature ductility, UHCS can have good tensile ductility but significantly higher strength than current automotive high strength steels. The material can also be made superplastic at intermediate temperatures and exhibits excellent die fill capability. Further… more
Date: December 4, 1995
Creator: Lesuer, D. R.; Syn, C. K. & Sherby, O. D.
Partner: UNT Libraries Government Documents Department
open access

Influence of severe plastic deformation on the structure and properties of ultrahigh carbon steel wire

Description: Ultrahigh-carbon steel wire can achieve very high strength after severe plastic deformation, because of the fine, stable substructures produce. Tensile strengths approaching 6000 MPa are predicted for UHCS containing 1.8%C. This paper discusses the microstructural evolution during drawing of UHCS wire, the resulting strength produced and the factors influencing fracture. Drawing produces considerable alignment of the pearlite plates. Dislocation cells develop within the ferrite plates and, with… more
Date: July 1, 1999
Creator: Leseur, D R; Sherby, O D & Syn, C K
Partner: UNT Libraries Government Documents Department
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