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in creator/contributor: "Syn, C.K."

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Use of microstructure control to toughen ferritic steels for cryogenic use. I. Fe--Ni steels

Alternation of austenitization and austenite + ferrite two-phase decomposition treatment in a cyclic thermal treatment allows the achievement of ultra-fine grain size in steels containing 8-12% Ni. The grain refinement leads to a substantial improvement in cryogenic mechanical properties. The ductile-brittle transition temperature of a ferritic Fe-12Ni-0.25Ti alloy was suppressed to below liquid helium temperature by this grain refinement procedure; the transition temperature of commercial ''9N… more

Date: December 1976

Creator: Syn, C. K.; Jin, S. & Morris, J. W. Jr.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Role of retained austenite on the toughness of steels with and without carbon. [9Ni; 8Ni--2Mn--0. 25Ti]

The presence of retained austenite suppresses the ductile-brittle transition temperature of the 9Ni steel (containing 0.1 percent carbon) in both impact testing and fracture toughness testing. However, in an interstitial-free Fe--8Ni--2Mn--0.25Ti steel, the benefit of retained austenite is seen only in impact testing, and little improvement in fracture toughness is observed. The stabilities of retained austenite in both alloy systems are compared in terms of chemical compositions and strain rat… more

Date: September 1, 1975

Creator: Morris, J. W. Jr.; Jin, S. & Syn, C. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Advances in the heat treatment of steels

A number of important recent advances in the processing of steels have resulted from the sophisticated uses of heat treatment to tailor the microstructure of the steels so that desirable properties are established. These new heat treatments often involve the tempering or annealing of the steel to accompish a partial or complete reversion from martensite to austenite. The influence of these reversion heat treatments on the product microstructure and its properties may be systematically discussed… more

Date: June 1, 1978

Creator: Morris, J. W., Jr.; Kim, J. I. & Syn, C. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Laminated metal composite formed from low flow stress layers and high flow stress layers using flow constraining elements and method of making same

This invention relates to a laminated metal composite, comprising alternating layers of low flow stress material and high flow stress material, and formed using flow constraining elements around each low flow stress layer; and a method of making same. A composite is a combination of at least two chemically distinct materials with a distinct interface separating the two materials. A metal matrix composite (MMC) is a composite material composed of a metal and a nonmetallic reinforcing agent such … more

Date: December 31, 1994

Creator: Syn, C. K. & Lesuer, D. R.

Item Type: Patent

Partner: UNT Libraries Government Documents Department

open access

Consequences of the re-transformation of precipitated austenite in ferritic cryogenic steels. Technical report No. 8

The re-transformation of precipitated austenite (..gamma../sub R/) in Fe-(6-9)%Ni steels has been investigated, with particular emphasis on the influence of transformation characteristics on alloy toughness at cryogenic temperature. In all cases studied the precipitated austenite re-transforms, either during cooling to cryogenic temperature or during deformation prior to fracture of the alloy. When the re-transformation is thermally induced the product martensite tends to form in a variant iden… more

Date: June 1, 1979

Creator: Morris, J. W., Jr.; Syn, C. K.; Kim, J. I. & Fultz, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Evolution of grain size distribution during deformation of superplastic materials

Grain size distribution and its evolution during superplastic deformation has been studied for two materials- ultrahigh carbon steel, which has a two phase microstructure, and a copper alloy, which has a quasi-single phase microstructure. For both materials the distribution of initial grain size is very accurately represented by a lognormal throughout the deformation history. The evolution of the parameters characterizing the log normal distribution have also been studied and found to vary in a… more

Date: October 28, 1997

Creator: Lesuer, D. R.; Glaser, R. & Syn, C. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Nano-subgrain Strengthening in Ball-milled Iron

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

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

MICROSTRUCTURE IN ADIABATIC SHEAR BANDS IN A PEARLITIC ULTRAHIGH CARBON STEEL

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

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Enhancing tensile ductility of a particulate-reinforced aluminum MMC by lamination with Mg-9% Li alloy

A laminated metal composite has been made by press bonding alternating layers of a particulate-reinforced aluminum MMC, 6090/SiC/25p, and a Mg-9%Li alloy. The mechanical properties including tensile ductility were evaluated. The tensile ductility of the Al MMC was found to increase from 3.5% to 11.5%. In contrast to other laminates based on ultrahigh carbon, steel, the laminate of this study and other Al MMC laminates exhibited tensile yield strengths that did not follow the rule of averages. T… more

Date: May 1995

Creator: Syn, C. K.; Lesuer, D. R. & Sherby, O. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Modeling the Evolution of Strength During Wire Drawing

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

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

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

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

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

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

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

Item Type: Article

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

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

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

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

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ultrahigh carbon steel for automotive applications

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.

Item Type: Article

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

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Laminated metals composites fracture and ballistic impact behavior

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Modeling microstructural evolution and the mechanical response of superplastic materials

A model has been developed that accounts for grain growth during, superplastic flow and its subsequent influence on stress-strain-strain rate behavior. These studies are experimentally based and have involved two different types of superplastic materials -- a quasi-single phase metal (Coronze 638) and a microduplex metal (ultrahigh-carbon steel - UHCS). In both materials the kinetics of strain-enhanced grain growth have been studied as a function of strain, strain rate and temperature. An equat… more

Date: January 11, 1993

Creator: Lesuer, D. R.; Syn, C. K.; Cadwell, K. L. & Preuss, C. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

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

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

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High Strain Rate-High Strain Response of an Ultrahigh Carbon Steel Containing 1.3% C and 3% SI

The mechanical response of a UHCS-1.3C material deformed at approximately 3000 s{sup -1} to large strains (60%) has been studied. The influence of three different heat treatments, which resulted in pearlitic, martensitic and tempered martensitic microstructures, on the stress-strain response has also been examined. Failure, at both the macroscopic and the microscopic levels, and the ability of the material to absorb energy in compression have been evaluated. Failure for all heat treatments occu… more

Date: February 19, 2003

Creator: Lesuer, D R; Syn, C K; Sherby, O M & Kum, D W

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

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

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

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Creep fracture during solute-drag creep and superplastic deformation

Creep fracture behavior has been studied in Al-Mg and Al-Mg-Mn alloys undergoing solute-drag creep and in microduplex stainless steel undergoing both solute-drag creep and superplastic deformation. Failure in these materials is found to be controlled by two mechanisms, neck formation and cavitation. The mechanism of creep fracture during solute-drag creep in Al-Mg is found to change from necking-controlled fracture to cavitation-controlled fracture as Mn content is increased. Binary Al-Mg mater… more

Date: October 1, 1996

Creator: Taleff, E. M.; Lesuer, D. R.; Syn, C. K. & Henshall, G. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Superplastic deformation in two microduplex stainless steels

The deformation behavior and mechanisms of superplastic flow in two microduplex stainless steels (SuperDux64 and Nitronic 19D) were studied at {similar_to}0.7T{sub m}. The two steels differed in initial grain size by a factor of 3. Both steels exhibited solute-drag-controlled grain boundary sliding in a high temperature {gamma}+{delta} phase field. In a lower temperature {gamma}+{sigma} phase field, the fine-grained steel ({bar L}=5{mu}m) exhibited climb-controlled grain boundary sliding and th… more

Date: September 1, 1996

Creator: Lesuer, D. R.; Nieh, T. G.; Syn, C. K. & Taleff, E. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mechanical behavior of ultrahigh strength ultrahigh carbon steel wire and rod

Ultrahigh-carbon steels (UHCSS) can achieve very high strengths in wire or rod form. These high strengths result from the mechanical work introduced during wire and rod processing. These strengths have been observed to increase with carbon content. In wire form, tensile strengths approaching 6000 MPa are predicted for UHCS containing 1. 8%C. In this paper, we will discuss the influence of processing (including rapid transformation during wire patenting) and micros ct- ure on the mechanical beha… more

Date: July 22, 1997

Creator: Lesuer, D. R.; Syn, C. K.; Sberby, O. D. & Whittenherger, W. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department