scholarly journals Size Effect on the Strength and Deformation Behavior of Glassy Carbon Nanopillars

MRS Advances ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 133-138 ◽  
Author(s):  
Almut Albiez ◽  
Ruth Schwaiger
Keyword(s):  
Size Effect ◽  
Glassy Carbon ◽  
Deformation Behavior ◽  
High Strength ◽  
Compression Tests ◽  
Failure Initiation ◽  
Initial Polymer ◽  
Constituent Material ◽  
Strength And Deformation ◽  
Very High

ABSTRACTGlassy carbon nanolattices can exhibit very high strength-to-weight ratios as a consequence of their small size and the material properties of the constituent material. Such nanolattices can be fabricated by pyrolysis of polymeric microlattices. To further elucidate the influence of the mechanical size effect of the constituent material, compression tests of glassy carbon nanopillars with varying sizes were performed. Depending on the specific initial polymer material and the nanopillar size, varying mechanical properties were observed. Small nanopillars exhibited elastic-plastic deformation before failure initiation. Moreover, for smaller nanopillars higher strength values were observed than for larger ones, which might be related to smaller defects and a lower defect concentration in the material.

Hot deformation behavior of low carbon advanced high strength steel (AHSS) microalloyed with boron

2009 ◽  
Vol 1243 ◽  
Author(s):  
I. Mejía ◽  
S. González-Sala ◽  
J.M. Cabrera
Keyword(s):  
High Temperature ◽  
Deformation Behavior ◽  
True Strain ◽  
High Strength ◽  
Tensile Tests ◽  
Strain Rates ◽  
Low Carbon ◽  
Compression Tests ◽  
Advanced High Strength Steel ◽  
Different Temperatures

ABSTRACTThis research work deals the influence of boron content on the high temperature deformation behavior of a low carbon advanced high strength steel (AHSS). For this purpose high temperature tensile and compression tests are carried out at different temperatures and constant true strain rates by using an Instron testing machine equipped with a radiant cylindrical furnace. Tensile tests are carried out at different temperatures (650, 750, 800, 900 and 1000°C) at a constant true strain rate of 0.001 s-1. Uniaxial hot compression tests are also performed over a wide range of temperatures (950, 1000, 1050 and 1100°C) and constant true strain rates (10-3, 10-2 and 10-1 s-1). In general, experimental results of hot tensile tests show an improvement of the hot ductility of the AHSS microalloyed with boron, although poor ductility at low temperatures (650 and 750°C). The fracture surfaces of the AHSS tested at temperatures showing the higher ductility (800, 900 and 1000°C) indicate that the fracture mode is a result of ductile failure, whereas in the region of poor ductility the fracture mode is of the ductile-brittle type failure. On the other hand, experimental results of hot compression tests show that both peak stress and peak strain tend to decrease in the AHSS microalloyed with boron, which indicates that boron generates a sort of solid solution softening effect in similar a way to other interstitial alloying elements in steel. Likewise, hot flow curves of the AHSS microalloyed with boron show an acceleration of the onset of dynamic recrystallization (DRX) and a delay of the recrystallization kinetics. Results are discussed in terms of boron segregation towards austenitic grain boundaries and second phase particles precipitation during plastic deformation and cooling.

Hot Deformation Behavior of a 3rd Generation Advanced High Strength Steel with a Medium-Mn Content

2015 ◽  
Vol 651-653 ◽  
pp. 120-125 ◽  
Author(s):  
Katharina Steineder ◽  
Martina Dikovits ◽  
Coline Beal ◽  
Christof Sommitsch ◽  
Daniel Krizan ◽  
...  
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
High Strength Steels ◽  
Rate Sensitivity ◽  
High Strength ◽  
Strain Rates ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Present Contribution ◽  
Mn Content

Medium-Mn steels are one of the promising candidates to achieve the desired mechanical properties in the 3rd generation of cold rolled advanced high strength steels (AHSS) for automotive applications. Their duplex microstructure consists of a ferritic matrix with a substantial amount of metastable retained austenite, which transforms to strain-induced martensite upon forming. This strengthening mechanism, well known as the TRansformation Induced Plasticity (TRIP) effect, provides the steel an excellent combination of high strength and elongation with a product of RmxA80 up to 30.000 MPa%. As hot rolling is one of the crucial steps during their production, the hot deformation behavior of Medium-Mn steels has to be thoroughly evaluated during their development stage.Therefore, the present contribution studied the hot deformation response of a 0.1 %C 5.5 %Mn steel by means of hot compression tests using a Gleeble® 3800 device. The influence of different deformation temperatures (900-1100 °C) and strain rates (0.1-10 s-1) on the stress-strain behavior was investigated. The flow curves were analyzed and corrected by the effects of adiabatic heating.Furthermore, the strain rate sensitivity m of the material was determined by evaluating stress values at different strain rates for given temperatures and strains. The m-values can be used to predict the deformation behavior of the material within the investigated range of parameters.Lastly, the hot working behavior of an alternative steel concept for a 3rd Generation AHSS with significantly lower Mn-content was comparatively investigated.

scholarly journals Compressive Deformation Behavior of Thick Micro-Alloyed HSLA Steel Plates at Elevated Temperatures

2017 ◽  
Vol 62 (2) ◽  
pp. 1191-1196
Author(s):  
J.-H. Lee ◽  
D.-O. Kim ◽  
K. Lee
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Hsla Steel ◽  
High Strength ◽  
Steel Plates ◽  
Compression Tests ◽  
Rate Dependent ◽  
Strength Constant

Abstract The hot deformation behavior of a heavy micro-alloyed high-strength low-alloy (HSLA) steel plate was studied by performing compression tests at elevated temperatures. The hot compression tests were carried out at temperatures from 923 K to 1,223 K with strain rates of 0.002 s−1 and 1.0 s−1. A long plateau region appeared for the 0.002 s−1 strain rate, and this was found to be an effect of the balancing between softening and hardening during deformation. For the 1.0 s−1 strain rate, the flow stress gradually increased after the yield point. The temperature and the strain rate-dependent parameters, such as the strain hardening coefficient (n), strength constant (K), and activation energy (Q), obtained from the flow stress curves were applied to the power law of plastic deformation. The constitutive model for flow stress can be expressed as σ = (39.8 ln (Z) – 716.6) · ε(−0.00955ln(Z) + 0.4930) for the 1.0 s−1 strain rate and σ = (19.9ln (Z) – 592.3) · ε(−0.00212ln(Z) + 0.1540) for the 0.002 s−1 strain rate.

scholarly journals Experimental behaviour of very high-strength concrete-encased steel composite column subjected to axial compression and end moment

2018 ◽  
Author(s):  
Zhenyu Huang ◽  
Xinxiong Huang ◽  
Weiwen Li ◽  
Yingwu Zhou ◽  
Lili Sui ◽  
...  
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Compression Tests ◽  
Plastic Design ◽  
Composite Column ◽  
Composite Columns ◽  
Strength Concrete ◽  
Steel Composite ◽  
Compressive Resistance ◽  
Very High

A type of cost-effective and very high strength concrete (VHSC) with 28-day compressive strength of 100-150 MPa is developed for applications in concrete-encased steel composite column constructions. This paper experimentally investigates the structural behaviour of VHSC encased steel composite columns based on a series of pure compression and eccentric compression tests. It is found that such high-strength composite column exhibits brittle post peak behaviour and low ductility but with acceptable compressive resistance. Throughout the tests, the main failure of VHSC encased column under compressive load is brittle spalling of concrete followed by local buckling of the reinforcement bars. The splitting and slippage may occur between concrete and steel section due to bending downward action. The confinement effect by the shear stirrups designed based on normal reinforced concrete codes may not be sufficient. Composite column subjected to initial flexural cracking due to end moment load with large eccentricity may experience degradation in the stiffness and ultimate resistance so that plastic design resistance may not be achieved. Analytical studies show that the N-M interaction model based on current design codes may over-predict the combined resistance of the composite columns. Therefore, a modified elastic-plastic design approach based on strain compatibility is developed to evaluate the compressive resistance of concrete encased composite columns. The validation against the test data shows a reasonable and conservative estimation on the combined resistance of VHSC encased composite columns. 

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

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.

ALCOA 7075

Alloy Digest ◽  
1998 ◽  
Vol 47 (7) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Surface Treatment ◽  
Stress Corrosion ◽  
Tensile Properties ◽  
Stress Corrosion Cracking ◽  
High Strength ◽  
Structural Parts ◽  
7075 Alloy ◽  
Very High

Abstract Alcoa 7075 alloy has very high strength and is used for highly stressed structural parts. The T7351 temper offers improved stress-corrosion cracking resistance. The alloy’s strength level equals or exceeds mild steels. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as machining and surface treatment. Filing Code: AL-350. Producer or source: ALCOA Wire, Rod & Bar Division.

UNS A97075

Alloy Digest ◽  
1986 ◽  
Vol 35 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
High Strength ◽  
Heat Treating ◽  
Good Resistance ◽  
Temperature Performance ◽  
Structural Applications ◽  
Structural Parts ◽  
Very High

Abstract UNS No. A97075 is a wrought precipitation-hardenable aluminum alloy. It has excellent mechanical properties, workability and response to heat treatment and refrigeration. Its typical uses comprise aircraft structural parts and other highly stressed structural applications where very high strength and good resistance to corrosion are required. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fatigue. It also includes information on low temperature performance as well as forming, heat treating, and machining. Filing Code: Al-269. Producer or source: Various aluminum companies.

ALLVAC 13-8

Alloy Digest ◽  
2002 ◽  
Vol 51 (11) ◽  
Keyword(s):  
Stainless Steel ◽  
Precipitation Hardening ◽  
Cold Working ◽  
High Strength ◽  
Heat Treating ◽  
General Corrosion ◽  
Single Treatment ◽  
Good Resistance ◽  
Temperature Performance ◽  
Very High

Abstract Allvac 13-8 has good fabricability and can be age hardened by a single treatment in the range 510-620 deg C (950-1150 deg F). Cold working prior to aging enhances the aging. This martensitic precipitation-hardening stainless steel has very good resistance to general corrosion and stress-corrosion cracking. It develops very high strength and exhibits good transverse ductility and toughness in heavy sections. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-866. Producer or source: Allvac Metals Company.

AIRSTEEL X-200

Alloy Digest ◽  
1959 ◽  
Vol 8 (6) ◽  
Keyword(s):  
United States ◽  
Fracture Toughness ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
United States Steel Corporation ◽  
Temperature Performance ◽  
Very High

Abstract USS AIRSTEEL X-200 is a very high strength, workable, air hardening steel. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SA-85. Producer or source: United States Steel Corporation.

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