Micro-morphology of Fatigue Crack Initiation and Propagation Behavior in High Strength Aluminum Alloy

High frequency fatigue crack propagation behavior of a nickel-base turbine disk alloy

Fatigue crack propagation tests were conducted on the powder metallurgy nickel-base superalloy KM4 at room temperature. Two different heat treatments were investigated, one which produced a relatively coarse grain size around 55 μm, and another which produced a very fine grain size around 6 μm. Tests were conducted at 50 Hz and 1000 Hz in an advanced servohydraulic testing machine at R-ratios b...

Crack Behavior of the Aluminum Alloy 2024 Under Fretting Conditions

The initial stage of fretting fatigue crack growth is significantly influenced by tangential force induced by fretting action along the contact surface where a mixed-mode crack growth is involved. Fretting crack behavior of aluminum alloy 2024 was studied, taking into account the problem of contact asperities. Finite element was used for the determination of the stress field near the contact su...

Accelerated Threshold Fatigue Crack Growth Effect – Powder Metallurgy Aluminum Alloy

Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low ∆K, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = Kmin/Kmax). The near threshold accelerated FCG rates are exacerbated by increased levels...

High Temperature Fatigue Crack Propagation in INCONEL718

Stress- Corrosion Crack Initiation of High-strength Pipeline Steel in Near-neutral pH Environments

Stress-corrosion cracking (SCC) tests were conducted in the near-neutral pH standard solution, NS4, and in an actual soil solution, using four-point bending at a high stress ratio and low frequency conditions very similar to those of operational pipelines. Pitting incubation appeared first and then pitting initiated and grew in both solutions although there were many more pits on the specimen t...