EFFECT OF THE AGE OF HIGH-STRENGTH MODIFIED CONCRETE MODIFIED ON ITS PHYSICOMECHANICAL PROPERTIES DURING PROLONGED HEATING TО 150°С

The demand for durable, resistant, and high-strength structural material has led to the use of fibers as reinforcing elements. This paper presents an investigation into the inclusion of chopped steel wool fibers (CSWFs) in cement to form a high-flexural strength cementitious composite matrix (CCM). CSWFs were used as the primary reinforcement in CCM at increments of 0.5 wt%, from 0.5–6 wt%, with ratios of cement to sand of 1:1.5 and water to cement of 0.45. The inclusion of CSWFs resulted in an excellent optimization of the physicomechanical properties of the CCM, such as its density (2.302 g/cm3), compressive strength (61.452 MPa), and maximum flexural strength (10.64 MPa), all of which exceeded the performances of other reinforcement elements reported in the literature.

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Decomposition of the metastable beta titanium alloy Ti-15-3

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075117 ◽

1983 ◽

Vol 41 ◽

pp. 264-265

Author(s):

Y. L. Chen ◽

S. Fujlshiro

Keyword(s):

Low Cost ◽

High Strength ◽

Alpha Phase ◽

Thick Sheet ◽

Omega Phase ◽

Beta Titanium Alloy ◽

Beta Titanium ◽

Beta Matrix ◽

Metastable Beta ◽

Very High

Metastable beta titanium alloys have been known to have numerous advantages such as cold formability, high strength, good fracture resistance, deep hardenability, and cost effectiveness. Very high strength is obtainable by precipitation of the hexagonal alpha phase in a bcc beta matrix in these alloys. Precipitation hardening in the metastable beta alloys may also result from the formation of transition phases such as omega phase. Ti-15-3 (Ti-15V- 3Cr-3Al-3Sn) has been developed recently by TIMET and USAF for low cost sheet metal applications. The purpose of the present study was to examine the aging characteristics in this alloy.The composition of the as-received material is: 14.7 V, 3.14 Cr, 3.05 Al, 2.26 Sn, and 0.145 Fe. The beta transus temperature as determined by optical metallographic method was about 770°C. Specimen coupons were prepared from a mill-annealed 1.2 mm thick sheet, and solution treated at 827°C for 2 hr in argon, then water quenched. Aging was also done in argon at temperatures ranging from 316 to 616°C for various times.

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Effects of cooling rate on the mechanical properties of dual phase treated vanadium steels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074896 ◽

1983 ◽

Vol 41 ◽

pp. 220-221

Author(s):

L.J. Chen ◽

H.C. Cheng ◽

J.R. Gong ◽

J.G. Yang

Keyword(s):

Mechanical Properties ◽

Cooling Rate ◽

Automobile Industry ◽

High Strength ◽

Weight Percent ◽

Low Alloy Steels ◽

Dual Phase ◽

Resource Requirement ◽

Alloy Steels ◽

Potential Weight

For fuel savings as well as energy and resource requirement, high strength low alloy steels (HSLA) are of particular interest to automobile industry because of the potential weight reduction which can be achieved by using thinner section of these steels to carry the same load and thus to improve the fuel mileage. Dual phase treatment has been utilized to obtain superior strength and ductility combinations compared to the HSLA of identical composition. Recently, cooling rate following heat treatment was found to be important to the tensile properties of the dual phase steels. In this paper, we report the results of the investigation of cooling rate on the microstructures and mechanical properties of several vanadium HSLA steels.The steels with composition (in weight percent) listed below were supplied by China Steel Corporation: 1. low V steel (0.11C, 0.65Si, 1.63Mn, 0.015P, 0.008S, 0.084Aℓ, 0.004V), 2. 0.059V steel (0.13C, 0.62S1, 1.59Mn, 0.012P, 0.008S, 0.065Aℓ, 0.059V), 3. 0.10V steel (0.11C, 0.58Si, 1.58Mn, 0.017P, 0.008S, 0.068Aℓ, 0.10V).

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The Nature of Delta Phase Precipitation in Inconel 718

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055916 ◽

1982 ◽

Vol 40 ◽

pp. 724-725

Author(s):

L. S. Lin ◽

C. C. Law

Keyword(s):

Inconel 718 ◽

Base Alloy ◽

High Strength ◽

Physical Metallurgy ◽

Nickel Base Alloy ◽

Phase Precipitation ◽

Weight Percentage ◽

Delta Phase ◽

The Subject ◽

Nickel Base

Inconel 718, a precipitation hardenable nickel-base alloy, is a versatile high strength, weldable wrought alloy that is used in the gas turbine industry for components operated at temperatures up to about 1300°F. The nominal chemical composition is 0.6A1-0.9Ti-19.OCr-18.0Fe-3Mo-5.2(Cb + Ta)- 0.1C with the balance Ni (in weight percentage). The physical metallurgy of IN 718 has been the subject of a number of investigations and it is now established that hardening is due, primarily, to the formation of metastable, disc-shaped γ" an ordered body-centered tetragonal structure (DO2 2 type superlattice).

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Physical, Chemical, and Crystallographic Characterization of Anodic Coatings on High Strength Aluminum Base Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100093146 ◽

1976 ◽

Vol 34 ◽

pp. 636-637

Author(s):

R. E. Herfert ◽

N. T. McDevitt

Keyword(s):

Sulfuric Acid ◽

Salt Spray ◽

High Strength ◽

Environmental Stability ◽

Anodic Films ◽

Sodium Dichromate ◽

Corrosion Resistant ◽

Aerospace Applications ◽

Bond Strengths ◽

Adhesive Bonded Joints

Durability of adhesive bonded joints in moisture and salt spray environments is essential to USAF aircraft. Structural bonding technology for aerospace applications has depended for many years on the preparation of aluminum surfaces by a sulfuric acid/sodium dichromate (FPL etch) treatment. Recently, specific thin film anodizing techniques, phosphoric acid, and chromic acid anodizing have been developed which not only provide good initial bond strengths but vastly improved environmental durability. These thin anodic films are in contrast to the commonly used thick anodic films such as the sulfuric acid or "hard" sulfuric acid anodic films which are highly corrosion resistant in themselves, but which do not provide good initial bond strengths, particularly in low temperature peel.The objective of this study was to determine the characteristics of anodic films on aluminum alloys that make them corrosion resistant. The chemical composition, physical morphology and structure, and mechanical properties of the thin oxide films were to be defined and correlated with the environmental stability of these surfaces in humidity and salt spray. It is anticipated that anodic film characteristics and corrosion resistance will vary with the anodizing processing conditions.

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HREM interface studies in SiC-whisker-reinforced Al2O3 and Si3N4 ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105734 ◽

1988 ◽

Vol 46 ◽

pp. 734-735

Author(s):

W. Braue ◽

R.W. Carpenter ◽

D.J. Smith

Keyword(s):

Analytical Data ◽

Base Material ◽

High Strength ◽

Ceramic Composites ◽

Good Thermal Stability ◽

All Ceramic ◽

Sic Whiskers ◽

Base Composite ◽

C 30 ◽

Si3n4 Ceramics

Whisker and fiber reinforcement has been established as an effective toughening concept for monolithic structural ceramics to overcome limited fracture toughness and brittleness. SiC whiskers in particular combine both high strength and elastic moduli with good thermal stability and are compatible with most oxide and nonoxide matrices. As the major toughening mechanisms - crack branching, deflection and bridging - in SiC whiskenreinforced Al2O3 and Si3N41 are critically dependent on interface properties, a detailed TEM investigation was conducted on whisker/matrix interfaces in these all-ceramic- composites.In this study we present HREM images obtained at 400 kV from β-SiC/α-Al2O3 and β-SiC/β-Si3N4 interfaces, as well as preliminary analytical data. The Al2O3- base composite was hotpressed at 1830 °C/60 MPa in vacuum and the Si3N4-base material at 1725 °C/30 MPa in argon atmosphere, respectively, adding a total of 6 vt.% (Y2O3 + Al2O3) to the latter to promote densification.

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