A single crystal of BCC iron is subjected to tensile stress of 100 MPa along the [001] direction. Which of the two slip systems ((211) –[ 111 ] or (321)–[ 111 ]) is going to yield first?

14) Inc a) Copper and its alloys do not fail due to cycling loading if the applied stress amplitude is below a certain level. b) Alloys with HCP crystal structure do not fail due to cycling loading if the applied stress amplitude is below a certain level. c) If there exist many slip systems such metals and alloys do not fail due to cycling loading if the applied stress amplitude is below a certain level. d) The practical rule that says there exist a fatigue limit for iron based alloys is not strictly true. 15) Indicate the incorrect expression: a) Better surface finish would help increase fatigue life. b) All kinds of inhomogenity would be detrimental in number of cycles that material can terms of the endure regardless of the stress level. c) Corrosion on a material that has excellent surface finish would not affect fatigue behavior of that part. d) Sand blasting as a source of compressive stresses would be useful under fatigue conditions

A cylindrical specimen of cold-worked steel has a Brinell hardness of 240. If the specimen remained cylindrical during deformation and its original radius was 11.8 mm, determine its radius after deformation. For steel, the dependence of tensile strength on percent cold work is shown in Animated Figure 7.19b. i mm

An iron specimen is plastically deformed in shear by 1%, and it has u dislocation density of 1 10 14 m/ m 3 Assume that the dislocation density did not change in the 1% strain of thisspecimen, the Burger's vector (b) is a 2 [1 1 1] the slip plane is (110). the shear stress isapplied to the (110) plane, and the lattice parameter of the BCC iron is 0.286 nm. Calculate the magnitude of the Burger's vector for these dislocations in iron. Calculate the average distance moved by the mobile dislocations as a result of the 1% shear strain.

Estimate the elastic and plastic strain at the ultimate tensile strength in the low-carbon steel specimen in Figure 6.16.

A copper rod is deformed using a uniaxial tensile force of 16000 N. Deformation continues until sufficient strain hardening has occurred such that the applied force is too small to allow further deformation. After deformation, the rod has a diameter of 0.01 m and a length of 1.5 m. Assume that copper follows the strain hardening lawwith K of 310 MPa and n=0.54   Please calculate the true strain after the deformation ?

1.4-7 The data shown in the table below were obtained from a tensile test of high-strength steel. The test specimen had a diameter of 13 mm and a gage length of 50 mm (see figure for Prob. 1.4-3). At fracture, the elongation between the gage marks was 3.0 mm and the minimum diameter was 10.7 mm. Plot the conventional stress-strain curve for the steefor the steel and determine the proportional limit, modulus of elastics of elastic- ity (i.e., the slope of the initial part of the stress-strain,tress-strain curve), yield stress at 0.1% offset, ultimate stress, percent, elongation in 50 mm, and percent reduction in area. 'ess, percent area. TENSILE-TEST DATA FOR PROB. 1.4-7 Elongation (mm) 0.005 0.015 0.048 Load (kN) 5 10 30 50 0.084 60 0.099 64.5 0.109 67.0 0.119 68.0 0.137 69.0 0.160 70.0 0.229 72.0 0.259 76.0 0.330 84.0 0.584 92.0 0.853 100.0 1.288 112.0 2.814 113.0 Fracture

A component made of Aluminium 6061-T651 has an edge crack with length equal to 15 mm, as shown The yield stress of the material is oy = 280 MPa and its fracture toughness (Kic) ranges from 40 MN/m3/2 to 60 MN/m³/2 Consider now the same edge crack in a semi-infinite plate. Determine the critical stress to avoid fracture. P I I I I ← 15 mm P↓ 100 mm 30 mm

An aluminum alloy [E = 67 GPa; ν = 0.33; α = 23.0 × 10–6/°C] plate is subjected to a tensile load P. The plate has a depth of d = 225 mm, a cross-sectional area of A = 5100 mm2, and a length of L = 4.1 m.  The initial longitudinal normal strain in the plate is zero. After load P is applied and the temperature of the plate has been increased by ΔT = 63°C, the longitudinal normal strain in the plate is found to be 2900 με.  Determine: (a) the magnitude of load P. (b) the change in plate depth Δd.

Problem 1 An aluminum rod is rigidly attached between a steel rod and a bronze rod as shown. Axial loads are applied at the positions indicated. Aluminum Steel A=800mm2 A=1000mm2 Bronze A=700mm? 4P 2P 500mm 600mm 700mm 1. What is the maximum value of P that will not exceed the axial stress bronze of 105 MPa? 2. What is the maximum value of P that will not exceed the axial stress in aluminum of 90 MPa? 3. If P=10KN, what is the axial force to be carried by the aluminum in KN? 4. If P is 5KN, what is the axial stress of steel?