Tensile Properties Of Metals Research Articles

Molecular dynamics study of the tensile properties of gold nanocrystalline films irradiated by gallium Ions

Understanding the effects of heavy ion irradiation on the tensile properties of metals at the nanoscale is important for the development of nanomechanical and other nanodevices using focused ion beam fabrication. This is both in terms of achieving the expected performance of designed devices and in potentially exploiting changes in mechanical properties to develop novel device concepts. We report investigation of the tensile properties of gold nanocrystalline films bombarded by high-energy Ga ions using molecular dynamics calculations. Ga ion irradiation leads to multiple grains with the redistribution of the grain boundaries (GBs). Importantly, Ga ion irradiation causes the film to become less ductile and more prone to fracture. The main reason is not surface damage caused by the sputtering effect of high-energy particles, but the convergence of GBs to the surface crater. On the other hand, for porous films with micropores in the GBs, irradiation results in the hardening of film and the ultimate tensile strength is larger than that of unirradiated counterpart.

Hardness and tensile properties of metals subjected to aging conditions

Many metals used in engineering applications are exposed to aging conditions such as ultraviolet radiation and moisture. Aged metals are expected to lose their designed mechanical properties, and it was desired to relate a degraded local property to other homogenous properties. To study the aging effect, steel and aluminum were tested with reproduced variables in an accelerated weather testing chamber. Multiple tensile specimens of steel and aluminum were created to undergo accelerated Q-Lab Ultraviolet testing in the presence of radiation, heat and moisture. Accelerated aging resulted in decreasing surface hardness correlating with the tensile strength and elastic modulus for both steel and aluminum. The study also investigated the change in hardness through the depth of specimens resulting from aging, exhibited more consistently in steels. The overall strongest correlations existed in steels, between surface hardness and tensile strength, analogous to other studies. Modeling linear relationships for metal lifetime forecasts from hardness has been supported by this study. Outcomes can be expanded upon with more elaborate finite element analysis if desired in future experimentation.

A study on determination of tensile properties of metals at elevated temperatures from spherical indentation tests

In this study, spherical indentation tests were used to determine the uniaxial tensile properties of metals at elevated temperatures (200 °C, 400 °C, and 600 °C). Taking the difference between spherical indentation tests at room and elevated temperatures into consideration, the incremental and analytical models were used to determine material parameters ( σ0, Ep, and n) and thermal softening parameters ( Eeff and m) in the Johnson–Cook constitutive equation, respectively. A discussion on the stability of the analytical model proved that despite in relative complicated forms and with three intercoupling material parameters, the analytical model is still effective for tensile property calculation. From the investigation on the relationship between pm and pi, it was found that correlating coefficient ξ is actually a function of both indentation depth and material parameters, and thus, a regression function was proposed for a more accurate description of ξ. Effectiveness of the spherical indentation tests was verified through experiments on three steels, SA508, 15CrMoR, S30408, and one titanium alloy, TC21, which proved that the spherical indentation tests can provide both proof and tensile strength calculations with a maximum error around 15% at room temperature and within 20% at elevated temperatures, and thus satisfy the demands for engineering applications.

Mechanical Testing of Micro-specimens of Al6061-T6 Using DIC for Strain Measurement

Tensile properties of metals are typically measured using dog-bone shaped specimens having dimensions as per specifications imposed by international standards organizations. However, these properties may be influenced by the size of the specimen, especially when the cross-sectional dimensions are lower. At lower length scales, microstructure could have an effect on the mechanical behavior. In this study, tensile experiments were conducted to investigate the effect of cross-sectional dimensions on Young’s modulus of Al6061-T6 materials. Due to the small size of the specimens, digital image correlation, a non-contact measurement technique was used to obtain strain filed in the gage section of the specimen. Spray paint or toner powder were used to produce speckle pattern on the specimen surface for better correlation of the images. For specimens having the thickness of the order of a fraction of a mm, the natural gray pattern observed on the surface of the specimen was found to provide a good speckle pattern. This natural speckle pattern was used to correlate the images instead of synthetic speckles, to avoid the effect of paint on the Young’s modulus being measured on specimens with cross-sectional dimensions below 1 mm. Young’s modulus was found to be constant at about 67 GPa for specimens whose area of cross-section was more than 3 mm2. When the area of cross-section was lesser, Young’s modulus was found to decrease with a decrease in area of cross-section. Larger spread in Young’s modulus was also observed in the specimens with area of cross-section < 1 mm2.

Application of the dynamic characterization of metals in automotive industry

This paper presents the experimental methodology used by R&D EMEA – Global Materials Labs Department to test metals at high strain rate of 500 s −1 . The implementation of dynamic results in commercial FEM Software LS – DYNA for crash simulation are presented. The effects of the strain rate on the tensile properties of metals, used in automotive field, are evaluated using results obtained from a direct tension split Hopkinson bar, built in collaboration with the University of Applied Sciences of Southern Switzerland DynaMat Lab. Finally the complete mechanical characterization of the Magnesium alloy AZ31B is presented, from static up to dynamic tests, showing its applications in FCA (Fiat Chrysler Automobiles), problems and future developments.

F404 Finite Element Simulation of Hydrogen Effects on the Tensile Properties of Metals and Alloys

F404 Finite Element Simulation of Hydrogen Effects on the Tensile Properties of Metals and Alloys

Manufacturing Aspects Relating to the Effects of Direct Current on the Tensile Properties of Metals

For metals, deformation is commonly conducted at elevated temperatures, reducing the overall process energy and cost. However, elevating the temperature has many drawbacks, including high tool/die adhesions, environmental reactivity, etc. Therefore, this study examines using an electrical current to reduce the deformation energy and presents electricity’s effects on the tensile properties of various materials. The influences of strain rate and cold work are also investigated. The results demonstrate that, when current flows through a metallic specimen, the material’s yield strength, flow stress, and elastic modulus are decreased; strain weakening occurs; and the total energy of deformation is decreased. These changes in the engineering stress-strain behavior occurred in all of the materials tested and are much greater than can be accounted for by resistive heating. However, the effects diminish with increasing strain rate. The analysis shows that applying electricity during deformation provides a viable alternative to increasing the workpiece temperature for deformation-based manufacturing processes.

Correlation of microstructure and tensile properties of 316 stainless steel weld metal solution annealed at high temperatures

The weld metal of AISI type 316 stainless steel, deposited by the gas tungsten arc welding process, was heat treated at 1323, 1373, and 1423 K. Study of the transformation kinetics showed that δ ferrite transformed to austenite at these aging temperatures. Optical microscopic studies of the weld metal showed that the amount of bferrite, its degree of inter connectivity, and its distribution decreased while the diameter/length ratio (d/l) increased, with increasing aging durations and temperatures. The austenite matrix evolved to reveal new recrystallised austenite grains on aging at 1423 Kfor 80 min. The results of tensile tests showed that the yield strength decreased while the ductility and work hardening exponent (n) increased with increasing aging times and temperatures. No significant change in ultimate tensile strength was observed. The changes in the amount, morphology, and distribution of δ ferrite did not influence the tensile properties. The weld metal aged at 1423 K for 80 min very nearly recovered to give properties similar to those of the base metal. Recovery and recrystallisation of austenite caused the observed changes in the weld metal tensile properties.

Correlation of microstructure and tensile properties of 316 stainless steel weld metal solution annealed at high temperatures

The weld metal of AISI type 316 stainless steel, deposited by the gas tungsten arc welding process, was heat treated at 1323, 1373, and 1423 K. Study of the transformation kinetics showed that δ ferrite transformed to austenite at these aging temperatures. Optical microscopic studies of the weld metal showed that the amount of bferrite, its degree of inter connectivity, and its distribution decreased while the diameter/length ratio (d/l) increased, with increasing aging durations and temperatures. The austenite matrix evolved to reveal new recrystallised austenite grains on aging at 1423 Kfor 80 min. The results of tensile tests showed that the yield strength decreased while the ductility and work hardening exponent (n) increased with increasing aging times and temperatures. No significant change in ultimate tensile strength was observed. The changes in the amount, morphology, and distribution of δ ferrite did not influence the tensile properties. The weld metal aged at 1423 K for 80 min very nearly recovered to give properties similar to those of the base metal. Recovery and recrystallisation of austenite caused the observed changes in the weld metal tensile properties.

Relevant Errors Associated with Tension Testing of Metals

Abstract The problems of properly evaluating the tensile properties of metals are examined. In particular, we estimate the errors introduced by the use of simplified relationships that do not consider the change in specimen volume during the test, and by ordinary regression analysis performed with only one uncertainty-affected variable. Typical values of these errors on different materials are computed by means of tension tests on cylindrical specimens.

Fire analyses from mechanical properties

This paper reports a preliminary investigation into the feasibility of determining fire causes by analysis of the tensile properties of metals.

Hydrogen embrittlement of metals

The deleterious effects of hydrogen on the tensile properties of metals are caused by the association and movement of hydrogen with dislocations. Hydrogen-dislocation interactions modify plastic deformation processes by stabilizing microcracks, by changing the work hardening rate, and by solid solution hardening. The extent to which such modifications cause embrittlement depends on the properties and defect structure of the uncharged alloy as well as on hydrogen-induced changes in deformation processes.

465. How radiation affects engineering materials: Richard E. Bowman, Materials in Design Engineering, 78, 119–134, July 1960

A summary is given of the ways in which radiation affects structural materials, inorganic nonmetallics. elastomers. plastics. and organic fluids. Most radiation effects, transient or permanent, are caused by gamma rays and neutrons. Structural materials are not so susceptible to radiation damage as the other materials. Radiation effects can be minimized by decreasing radiation dose, or increasing temperatures during irradiation. The damage can be repaired or removed by annealing. The effects of neutron irradiation on the tensile properties of metals are sunnmarized in tables. Inorganic materials show many changes in physical and mechanical properties. The inorganic materials studied include graphite, carbides, glass, ceramics, and related materials. Elastomers vary widely in radiation resistance owing to the use of filters, additives, and radiation-resistant resins. In general, the radiation resistance of plastics was found to be equal to, or better than, that of elastomers. Composition adjustment in organic fluids was used to increase radiation resistance. (M.C.G.)

The penetration of hydrogen into metal cathodes and its effect upon the tensile properties of metals and their resistance to repeated stresses

The penetration of hydrogen into metal cathodes and its effect upon the tensile properties of metals and their resistance to repeated stresses

The penetration of hydrogen into metal cathodes and its effect upon the tensile properties of metals and their resistance to repeated stresses; with a note on the effect of non electrolytic baths and nickel plating on these properties

The attention of a number of workers has been directed to the effect of occluded hydrogen on the static properties of metals and particularly its effect in producing brittleness. In connection with many industrial processes pickling is resorted to and not infrequently a brittle condition of the metal is produced by the process. The occlusion of hydrogen has been offered as an explanation. Pfeil ( loc. cit .) has shown that the behaviour of fine grained iron is different from that of a single crystal when tested as a cathode, and that the hydrogen penetrates between boundaries of crystals. Edwards has shown that hydrogen passes through crystals of iron. Pfeil has also shown that:— (1) The tensile strength of a fine grained iron is not affected by the hydrogen penetration but the elongation was very considerably reduced. (2) That the temperature of the electrolytic bath considerably affects the elongation and that removal of a specimen from the bath allows the hydrogen to escape from the crystal boundaries and the material to return to its normal condition.