Critical resolved shear stress of lead

This study deals with the numerical estimation of the fatigue life represented in the form of strength-life (S-N, or Wöhler) curves of metals with different crystallographic structures, namely body-centered cubic (BCC) and face-centered cubic (FCC). Their life curves are determined by analyzing the initiation of a short crack under the influence of microstructure and subsequent growth of the long crack, respectively. Micro-models containing microstructures of the materials are set up by using the finite element method (FEM) and are applied in combination with the Tanaka-Mura (TM) equation in order to estimate the number of cycles required for the crack initiation. The long crack growth analysis is conducted using the Paris law. The study shows that the crystallographic structure is not the predominant factor that determines the shape and position of the fatigue life curve in the S-N diagram, but it is rather the material parameter known as the critical resolved shear stress (CRSS). Even though it is an FCC material, the investigated austenitic stainless steel AISI 304 shows an untypically high fatigue limit (208 MPa), which is higher than the fatigue limit of the BCC vanadium-based micro-alloyed forging steel AISI 1141 (152 MPa).

Download Full-text

A Newly Discovered Relation between the Critical Resolved Shear Stress and the Fatigue Endurance Limit for Metallic Materials

Metals ◽

10.3390/met10060803 ◽

2020 ◽

Vol 10 (6) ◽

pp. 803

Author(s):

Marijo Mlikota ◽

Siegfried Schmauder

Keyword(s):

Shear Stress ◽

Endurance Limit ◽

Multiscale Approach ◽

Metallic Materials ◽

Strong Indication ◽

The Past ◽

Simulation Based ◽

New Perspective ◽

Critical Resolved Shear Stress ◽

Fatigue Endurance

The paper introduces a valuable new description of fatigue strength in relation to material properties and thus a new perspective on the overall understanding of the fatigue process. Namely, a relation between the endurance limits and the accompanying values of the critical resolved shear stress (CRSS) for various metallic materials has been discovered by means of a multiscale approach for fatigue simulation. Based on the uniqueness of the relation, there is a strong indication that it is feasible to relate the endurance limit to the CRSS and not to the ultimate strength, as often done in the past.

Download Full-text

Effect of Temperature and Crystal Orientation on the Plasticity (SLIP) Evolution in Single Crystal Nickel Base Superalloy Notched Specimens

Volume 5: Turbo Expo 2007 ◽

10.1115/gt2007-27095 ◽

2007 ◽

Author(s):

Shadab Siddiqui ◽

Nagaraj K. Arakere ◽

Fereshteh Ebrahimi

Keyword(s):

Shear Stress ◽

Single Crystal ◽

Element Model ◽

Effect Of Temperature ◽

Nickel Base Superalloy ◽

Shear Stresses ◽

Slip Systems ◽

Slip Planes ◽

Nickel Base ◽

Critical Resolved Shear Stress

A comprehensive numerical investigation of plasticity (slip) evolution near notches was conducted at 28°C and 927°C, for two crystallographic orientations of double-notched single crystal nickel base superalloys (SCNBS) specimens. The two specimens have a common loading orientation of <001> and have notches parallel to the <010> (specimen I) and <110> (specimen II) orientation, respectively. A three dimensional anisotropic linear elastic finite element model was employed to calculate the stress field near the notch of these samples. Resolved shear stress values were obtained near the notch for the primary octahedral slip systems ({111} <110>) and cube slip systems ({100} <110>). The effect of temperature was incorporated in the model as changes in the elastic modulus values and the critical resolved shear stress (CRSS). The results suggest that the number of dominant slip systems (slip systems with the highest resolved shear stress) and the size and the shape of the plastic zones around the notch are both functions of the orientation as well as the test temperature. A comparison between the absolute values of resolved shear stresses near the notch at 28°C and 927°C on the {111} slip planes revealed that the plastic zone size and the number of activated dominant slip systems are not significantly affected by the temperature dependency of the elastic properties of the SCNBS, but rather by the change in critical resolved shear stress of this material with temperature. The load required to initiate slip was found to be lower in specimen II than in specimen I at both temperatures. Furthermore, at 927°C the maximum resolved shear stress (RSS) on the notch surface was found to be greater on the {100} slip planes as compared with the {111} slip planes in both specimens. The results from this study will be helpful in understanding the slip evolution in SCNBS at high temperatures.

Download Full-text

On the problem of the critical resolved shear stress saturation at low temperatures

Scripta Metallurgica et Materialia ◽

10.1016/0956-716x(95)90853-c ◽

1995 ◽

Vol 32 (4) ◽

pp. 647-650

Author(s):

J.M. Galligan ◽

L.N. Gumen ◽

A.A. Krokhin

Keyword(s):

Shear Stress ◽

Low Temperatures ◽

Critical Resolved Shear Stress

Download Full-text

Plastic Deformations in L10-Ordered Single Crystals with their c/a Ratios Less than Unity

Materials Science Forum ◽

10.4028/www.scientific.net/msf.561-565.459 ◽

2007 ◽

Vol 561-565 ◽

pp. 459-462

Author(s):

Katsushi Tanaka ◽

Hiromitsu Ide ◽

Yoshinori Sumi ◽

Kyosuke Kishida ◽

Haruyuki Inui

Keyword(s):

Shear Stress ◽

Temperature Dependence ◽

Single Crystals ◽

Room Temperature ◽

The Other ◽

Compressive Deformation ◽

Positive Temperature ◽

Plastic Deformations ◽

Temperature Range ◽

Critical Resolved Shear Stress

Compressive deformation of L10-ordered single crystals of FePd whose c/a ratio less than unity have been investigated from room temperature to 823 K. The results show that the critical resolved shear stress (CRSS) for octahedral glide of ordinary dislocations is smaller than that of super-lattice dislocations in all the temperature range investigated, that is the opposite sense to the case of Ti-56 mol% Al. The CRSS for ordinary dislocations virtually independent to the temperature. On the other hand, the CRSS for super dislocations exhibits a weak positive temperature dependence from room temperature up to 573 K and decreases in higher temperatures.

Download Full-text