Biaxial Low Cycle Fatigue for Notched, Cracked, and Smooth Specimens at High Temperatures

1988 ◽  
Vol 110 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Masao Sakane ◽  
Masateru Ohnami ◽  
Naomi Hamada
Keyword(s):  
Low Cycle Fatigue ◽  
Equivalent Stress ◽  
Torsion Test ◽  
Maximum Principal Stress ◽  
304 Stainless Steel ◽  
Cycle Fatigue ◽  
Failure Data ◽  
Biaxial Fatigue ◽  
Failure Life ◽  
Type 304

Push-pull and reversed torsion tests were carried out for notched, precracked, and smooth hollow cylindrical specimens of type 304 stainless steel at 923K in air. This paper describes the crack direction in the three types of specimens and the parameter that correlates the biaxial low cycle fatigue failure data. All types of specimens, except the smooth specimen in the reversed torsion test, failed by mode I cracking. Failure life of the specimens was discussed in connection with the crack mode. The equivalent stress based on COD could correlate the biaxial fatigue data whereas the Mises’ equivalent stress and the maximum principal stress could not.

Fracture Modes and Low Cycle Biaxial Fatigue Life at Elevated Temperature

1987 ◽  
Vol 109 (3) ◽  
pp. 236-243 ◽  
Author(s):  
M. Sakane ◽  
M. Ohnami ◽  
M. Sawada
Keyword(s):  
Low Cycle Fatigue ◽  
Surface Oxidation ◽  
Strain Ratio ◽  
Growth Direction ◽  
Principal Strain ◽  
304 Stainless Steel ◽  
Cycle Fatigue ◽  
Biaxial Fatigue ◽  
Crack Growth Direction ◽  
Typical Strain

This paper describes the crack growth direction in biaxial low cycle fatigue under combined axial and torsional stresses in hollow cylindrical specimens of type 304 stainless steel at 923 K in air. Three types of crack are identified, namely macrocrack greater than 1 mm in length, subcracks between 0.1 mm and 1.0 mm in length, and microcracks less than 0.1 mm in length. The macrocrack direction as well as that of the subcrack depends on the principal strain ratio but the microcrack is mode I for all the principal strain ranges tested. The connection of the three types of crack is discussed in relation to the surface oxidation. Typical strain stress and criteria for the biaxial low cycle fatigue failure are applied to the experimental data and their applicability is discussed.

High Temperature Low-Cycle Fatigue of Friction Welded Joints-Type 304-304 Stainless Steel and Alloy 718-718 Nickel Base Superalloy

1993 ◽  
Vol 115 (1) ◽  
pp. 109-115
Author(s):  
T. Wakai ◽  
M. Sakane ◽  
M. Ohnami ◽  
K. Okita ◽  
Y. Fukuchi
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Fatigue Strength ◽  
Base Metal ◽  
Welded Joints ◽  
Low Cycle Fatigue ◽  
304 Stainless Steel ◽  
Alloy 718 ◽  
Cycle Fatigue ◽  
Type 304

This paper assesses the high-temperature low-cycle fatigue of the Type 304 stainless steel and Alloy 718 superalloy friction-welded joints. Strain controlled low-cycle fatigue tests for 304-304 and 718-718 friction-welded specimens were carried out at 923K in air to obtain the fatigue strength of the joints. These materials were selected as the cyclic hardening and softening materials, respectively. The 304-304 welded specimens showed inferior fatigue strength in comparison with the base metal while the 718-718 specimens exhibited fatigue strength equivalent to that of the base metal. The difference in the fatigue strength between the two materials is discussed from the viewpoint of the cyclic deformation behavior and strain reduction at weld interface.

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