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Strength Steel (strength + steel)

Distribution by Scientific Domains
Polymers and Materials Science80%

Selected Abstracts

Designing Ultrahigh Strength Steels with Good Ductility by Combining Transformation Induced Plasticity and Martensite Aging

ADVANCED ENGINEERING MATERIALS, Issue 7 2009
Dierk Raabe
We present results on precipitation hardened ductile high strength maraging-TRIP steels with up to 1.5 GPa strength and good ductility. The alloys have low carbon content (0.01 wt% C), 9,15 wt% Mn, and additions of Ni, Ti, and Mo (1,2 wt%) for precipitation. Martensite aging leads to a surprising simultaneous increase in strength and total elongation for samples with 9 wt% Mn and 12 wt% Mn. [source]

Plasticity-fibre model for steel triangular plate energy dissipating devices

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 9 2002
Chung-Che Chou
Abstract Properly fabricated triangular-plate added damping and stiffness (TADAS) devices can sustain a large number of yield reversals without strength degradation, thereby dissipating a significant amount of earthquake-induced energy. A pronounced isotropic-hardening effect is recognized in the force-deformation relationships of the TADAS devices made from two grades of low yield strength steel. The proposed plasticity-fibre model employing two surfaces (a yield surface and a bounding surface) in plasticity theory accurately predicts the experimental responses of the TADAS devices. This model is also implemented into a computer program DRAIN2D+ to investigate a frame response with the TADAS devices. Substructure pseudo-dynamic tests and analytical studies of a two-storey steel frame constructed with the low yield strength steel, LYP-100 or LYP-235 grade, TADAS devices confirm that the dynamic structural response can only be predicted if the proposed plasticity-fibre model is used for LYP-100 steel TADAS device. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Microstructures and adiabatic shear bands formed by ballistic impact in steels and tungsten alloy

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 12 2003
Z. Q. DUAN
ABSTRACT Projectiles of sintered tungsten alloy were fired directly at two kinds of steel target plates. The microstructures near the perforation of a medium, 0.45% carbon steel target plate can be identified along the radial direction as: melted and rapidly solidified layer, recrystallized fine-grained layer, deformed fine-grained layer, deformed layer and normal matrix. The adiabatic shear bands cannot be found in this intermediate strength steel. The microstructures along the radial direction of perforation of 30CrMnMo steel target plate are different from that of the medium carbon steel. There was a melted and rapidly solidified layer on the surface of the perforation, underneath there was a diffusing layer, and then fine-grained layer appeared as streamlines. Several kinds of adiabatic shear bands were found in this higher strength steel; they had different directions and widths, which were relative to the shock waves, as well as the complex deformation process of penetration. The deformation of the projectiles was rather different when they impacted on target plates of medium carbon steel and 30CrMnMo steel. The projectile that impacted on the medium carbon steel target plate was tamped and its energy dissipated slowly, while that which impacted on the 30CrMnMo steel target plate was sheared and the energy dissipated quickly. [source]

On the mechanism of fatigue failure in the superlong life regime (N>107 cycles).

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2000
Part 1: influence of hydrogen trapped by inclusions
The fracture surfaces of specimens of a heat-treated hard steel, namely Cr,Mo steel SCM435, which failed in the regime of N,=,105 to 5,×,108 cycles, were investigated by optical microscopy and scanning electron microscopy (SEM). Specimens having a longer fatigue life had a particular morphology beside the inclusion at the fracture origin. The particular morphology looked optically dark when observed by an optical microscope and it was named the optically dark area (ODA). The ODA looks a rough area when observed by SEM and atomic force microscope (AFM). The relative size of the ODA to the size of the inclusion at the fracture origin increases with increase in fatigue life. Thus, the ODA is considered to have a crucial role in the mechanism of superlong fatigue failure. It has been assumed that the ODA is made by the cyclic fatigue stress and the synergetic effect of the hydrogen which is trapped by the inclusion at the fracture origin. To verify this hypothesis, in addition to conventionally heat-treated specimens (specimen QT, i.e. quenched and tempered), specimens annealed at 300 °C in a vacuum (specimen VA) and the specimens quenched in a vacuum (specimen VQ) were prepared to remove the hydrogen trapped by inclusions. The specimens VA and VQ, had a much smaller ODA than the specimen QT. Some other evidence of the influence of hydrogen on superlong fatigue failure are also presented. Thus, it is concluded that the hydrogen trapped by inclusions is a crucial factor which causes the superlong fatigue failure of high strength steels. [source]