G0301402 Influence of Strain Amplitude on Dislocation Interaction of Primary and Secondary Slip Systems in a Tricrystal Model during Cyclic Deformation

2015 ◽  
Vol 2015 (0) ◽  
pp. _G0301402--_G0301402-
Author(s):  
Ryouji KONDOU ◽  
Tetuya OHASHI
Keyword(s):  
Strain Amplitude ◽  
Cyclic Deformation ◽  
Slip Systems ◽  
Dislocation Interaction ◽  
Secondary Slip

Observation of secondary slip systems in tungsten bicrystals

1984 ◽  
Vol 42 ◽  
pp. 478-479
Author(s):  
J. R. Fekete ◽  
R. Gibala
Keyword(s):  
Stress Field ◽  
Grain Boundaries ◽  
Deformation Behavior ◽  
Stress Axis ◽  
Polycrystalline Materials ◽  
Slip Systems ◽  
Metallic Materials ◽  
Twist Boundary ◽  
Secondary Slip ◽  
Plane Normal

The deformation behavior of metallic materials is modified by the presence of grain boundaries. When polycrystalline materials are deformed, additional stresses over and above those externally imposed on the material are induced. These stresses result from the constraint of the grain boundaries on the deformation of incompatible grains. This incompatibility can be elastic or plastic in nature. One of the mechanisms by which these stresses can be relieved is the activation of secondary slip systems. Secondary slip systems have been shown to relieve elastic and plastic compatibility stresses. The deformation of tungsten bicrystals is interesting, due to the elastic isotropy of the material, which implies that the entire compatibility stress field will exist due to plastic incompatibility. The work described here shows TEM observations of the activation of secondary slip in tungsten bicrystals with a [110] twist boundary oriented with the plane normal parallel to the stress axis.

scholarly journals Cyclic Deformation of Semi-solid Processed Magnesium Alloys

2021 ◽  
Author(s):  
Himesh Patel
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloys ◽  
Strain Amplitude ◽  
Cyclic Deformation ◽  
Weight Ratio ◽  
Aging Treatment ◽  
Strain Ratio ◽  
Plastic Strain Amplitude ◽  
Total Strain Amplitude ◽  
Semi Solid

To improve fuel economy and reduce greenhouse gas emissions, magnesium alloys are being considered for automotive and aerospace applications because of their high strength-to-weight ratio. The objective of this thesis was to study monotonic and cyclic deformation behavior of two semi-solid processed (thixomolded) magnesium alloys, AZ91D and AM60B. The fatigue life of these thixomolded alloys was observed to be higher than that of their die cast counterparts. As the total strain amplitude increased, the stress amplitude and plastic strain amplitude increased, while the pseudoelastic modulus decreased. The change in the modulus was attributed to the nonlinear (pseudoelastic) behavior caused by twinning-detwinning during cyclic deformation. The fatigue life increased with decreasing strain ratio, and partial mean stress relaxation occurred mainly in the initial 10-20% of the fatigue life. The fatigue life of theAM60B alloy improved after solution or solution-aging treatment, and the monotonic strength increased by aging, while the thixomolded condition itself exhibited moderate monotonic strength and fatigue life.

scholarly journals Cyclic Deformation Behavior of A Heat-Treated Die-Cast Al-Mg-Si-Based Aluminum Alloy

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4115
Author(s):  
Sohail Mohammed ◽  
Shubham Gupta ◽  
Dejiang Li ◽  
Xiaoqin Zeng ◽  
Daolun Chen
Keyword(s):  
Heat Treatment ◽  
Strain Amplitude ◽  
Cyclic Deformation ◽  
Stress Amplitude ◽  
Cyclic Hardening ◽  
Life Cycles ◽  
Total Strain ◽  
Total Strain Amplitude ◽  
Heat Treated ◽  
Die Cast

The purpose of this investigation was to study the low-cycle fatigue (LCF) behavior of a newly developed high-pressure die-cast (HPDC) Al-5.5Mg-2.5Si-0.6Mn-0.2Fe (AlMgSiMnFe) alloy. The effect of heat-treatment in comparison with its as-cast counterpart was also identified. The layered (α-Al + Mg2Si) eutectic structure plus a small amount of Al8(Fe,Mn)2Si phase in the as-cast condition became an in-situ Mg2Si particulate-reinforced aluminum composite with spherical Mg2Si particles uniformly distributed in the α-Al matrix after heat treatment. Due to the spheroidization of intermetallic phases including both Mg2Si and Al8(Fe,Mn)2Si, the ductility and hardening capacity increased while the yield stress (YS) and ultimate tensile strength (UTS) decreased. Portevin–Le Chatelier effect (or serrated flow) was observed in both tensile stress–strain curves and initial hysteresis loops during cyclic deformation because of dynamic strain aging caused by strong dislocation–precipitate interactions. The alloy exhibited cyclic hardening in both as-cast and heat-treated conditions when the applied total strain amplitude was above 0.4%, below which cyclic stabilization was sustained. The heat-treated alloy displayed a larger plastic strain amplitude and a lower stress amplitude at a given total strain amplitude, demonstrating a superior fatigue resistance in the LCF regime. A simple equation based on the stress amplitude of the first and mid-life cycles ((Δσ/2)first, (Δσ/2)mid) was proposed to characterize the degree of cyclic hardening/softening (D): D=±(Δσ/2)mid − (Δσ/2)first(Δσ/2)first, where the positive sign “+” represents cyclic hardening and the negative sign “−“ reflects cyclic softening.

The Orientation Dependence of Work?Hardening in Crystals of Face-centred Cubic Metals

1960 ◽  
Vol 13 (2) ◽  
pp. 316 ◽  
Author(s):  
LM Clarebrough ◽  
ME Hargreaves
Keyword(s):  
Shear Stress ◽  
Slip Plane ◽  
Work Hardening ◽  
Orientation Dependence ◽  
Slip Systems ◽  
Deformation Bands ◽  
Secondary Slip ◽  
Cubic Metals ◽  
Primary Slip Plane

It is shown that the principal features of the observed orientation dependence of work-hardening can be accounted for in terms of the likelihood of formation. Of Lomer-Cottrell sessile dislocations in two directions in tb" primary slip plane. This is deduced from the known variation of resolved shear stress with orientation, for the possible secondary slip systems, and metallographic observations of slip and deformation bands.

Effects of Strain Amplitude and Loading Path on Cyclic Behavior and Martensitic Transformation of 304 Stainless Steel

2018 ◽  
Author(s):  
Yajing Li ◽  
Dunji Yu ◽  
Xu Chen
Keyword(s):  
Stainless Steel ◽  
Martensitic Transformation ◽  
Strain Amplitude ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Secondary Hardening ◽  
304 Stainless Steel ◽  
Loading Path ◽  
Martensite Content ◽  
Number Of Cycles

Effects of strain amplitude and loading path on cyclic deformation behavior and martensitic transformation of 304 stainless steel were experimentally investigated at room temperature. Series of symmetrical strain-control low cycle fatigue tests with strain amplitude ranging from 0.4% to 1.0% and various loading paths (uniaxial, torsional, proportional, rhombus, square and circular) with the same equivalent strain amplitude of 0.5% were carried out. Three-stage cyclic deformation behavior containing initial hardening, cyclic softening or saturation, and secondary hardening as well as near-linear relationship between α’-martensite content and number of cycles was observed during the whole life regime as for each test. Besides, a nearly linear relation between peak stress and α’-martensite content was found during secondary hardening stage. Furthermore, higher strain amplitude or non-proportionality of loading path resulted in higher cyclic stress response and α’-martensite content growth rate, defined by the slope of curves of α’-martensite content versus number of cycles.

Bending Ductility of Heavily Cold-Rolled Ni3Al Thin Foils

2002 ◽  
Vol 753 ◽  
Author(s):  
Satoru Kobayashi ◽  
Masahiko Demura ◽  
Kyosuke Kishida ◽  
Toshiyuki Hirano
Keyword(s):  
Cold Rolling ◽  
Shear Bands ◽  
Slip Systems ◽  
Dislocation Interaction ◽  
Fracture Elongation ◽  
Thin Foils ◽  
Slip Planes ◽  
Cold Rolled ◽  
Bending Mechanism ◽  
Slip Deformation

ABSTRACTOur recent studies revealed that heavily cold-rolled Ni3Al foils have a good bending ductility in spite of almost no elongation in tensile test. In this paper, bending characteristics of 95% cold-rolled foils around transverse and rolling directions (TD and RD, respectively) were examined to understand the bending mechanism. Fracture elongation on the tension surface shows a large bending anisotropy: 5 % for the TD bending, while less than 1% for the RD bending. The bending ductility is due to {111}<110> slip deformation. In the TD bending, slip occurs on the slip systems operated during cold rolling, and cracks initiate along the shear bands. In the RD bending, slip occurs on the other {111} planes besides the slip planes operated during cold rolling, and fracture occurs as a result of the dislocation interaction in the both planes.

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