Topic
Stress corrosion cracking
About: Stress corrosion cracking is a research topic. Over the lifetime, 11340 publications have been published within this topic receiving 138157 citations.
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01 Jan 2015
TL;DR: In this article, the early stage of crack growth was studied by performing in situ long focal length microscope (500X) crack length measurements in laboratory air and 1% NaCl environments.
Abstract: The corrosion fatigue crack growth characteristics of small (less than 35 microns) surface and corner cracks in aluminum alloy 7075 is established. The early stage of crack growth is studied by performing in situ long focal length microscope (500X) crack length measurements in laboratory air and 1% NaCl environments. To quantify the "small crack effect" in the corrosive environment, the corrosion fatigue crack propagation behavior of small cracks is compared to long through-the-thickness cracks grown under identical experimental conditions. In salt water, long crack constant K(sub max) growth rates are similar to small crack da/dN.
50 citations
TL;DR: Linearly increasing stress tests conducted in 30°C aerated distilled water using as-quenched 4340 and 3.5NiCrMoV turbine rotor steels indicated that stress corrosion cracking occurred at all applied stress rates for 4340 steel, whilst only at applied stress rate less than or equal to 0.002 MPa−s−1 for the turbine rotor steel as discussed by the authors.
50 citations
TL;DR: The film-induced cleavage model of stress-corrosion cracking (SCC) has been tested using an Ag-20 at. pct Au alloy in 1 M HClO4 solution as discussed by the authors.
Abstract: The film-induced cleavage model of stress-corrosion cracking (SCC) has been tested using an Ag-20 at. pct Au alloy in 1 M HClO4 solution. Brittle cracks, both intergranular (IG) and transgranular (TG) in nature, were formed by high-speed loading of a thin foil covered with a dealloyed (nanoporous gold) layer. These cracks were found to propagate through the dealloyed layer and into the uncorroded bulk face-centered cubic (fcc) material for a distance of many microns. Hydrogen embrittlement (HE) can be excluded on thermodynamic grounds; thus, only film-induced cleavage can explain the observed decoupling of stress and corrosion in the fracture process.
50 citations
TL;DR: A detailed examination of the fracture surfaces in an attempt to understand the SCC fracture mechanism was presented in this paper. But the results of the analysis were limited to the fracture surface of a single bolt.
Abstract: Rock bolts have failed by Stress Corrosion Cracking (SCC). This paper presents a detailed examination of the fracture surfaces in an attempt to understand the SCC fracture mechanism. The SCC fracture surfaces, studied using Scanning Electron Microscopy (SEM), contained the following different surfaces: Tearing Topography Surface (TTS), Corrugated Irregular Surface (CIS) and Micro Void Coalescence (MVC). TTS was characterised by a ridge pattern independent of the pearlite microstructure, but having a spacing only slightly coarser than the pearlite spacing. CIS was characterised as porous irregular corrugated surfaces joined by rough slopes. MVC found in the studied rock bolts was different to that in samples failed in a pure ductile manner. The MVC observed in rock bolts was more flat and regular than the pure MVC, being attributed to hydrogen embrittling the ductile material near the crack tip. The interface between the different fracture surfaces revealed no evidence of a third mechanism involved in the transition between fracture mechanisms. The microstructure had no effect on the diffusion of hydrogen nor on the fracture mechanisms. The following SCC mechanism is consistent with the fracture surfaces. Hydrogen diffused into the material, reaching a critical concentration level. The thus embrittled material allowed a crack to propagate through the brittle region. The crack was arrested once it propagated outside the brittle region. Once the new crack was formed, corrosion reactions started producing hydrogen that diffused into the material once again.
50 citations
TL;DR: In this paper, two commercially-processed Al-6Zn-2Mg alloys, 7050 and a low copper, were tested for susceptibility to embrittlement by precharged hydrogen and by simultaneous cathodic charging and straining (SET procedure).
Abstract: Two commercially-processed Al-6Zn-2Mg alloys, 7050 and a “low copper” 7050, were tested for susceptibility to embrittlement by precharged hydrogen and by simultaneous cathodic charging and straining (SET procedure). Specimens were heat treated to underaged, peak-strength aged, and overaged conditions. In 7050, the peak strength and overaged conditions were not embrittled by hydrogen, though underaged material showed marked embrittlement. All microstructures tested for the low-copper alloy were embrittled. The results agree with the microstructural rationale established through earlier work on 7075 and 2124 aluminum alloys, particularly with respect to the susceptibility of underaged material to hydrogen. As in earlier work, the extent of dislocation transport of hydrogen, and local hydrogen accumulation at grain boundaries, evidently controlled the extent and degree of brittle fracture. These three important alloys can now be ranked in the order 7050, 2124, 7075 of increasing relative susceptibility to theonset of stress corrosion cracking.
50 citations