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Picture for Environmentally-Assisted Cracking of Martensitic Stainless Steel Octg Material in H2S-Saturated Condition at Room Temperature to Elevated Temperature
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Environmentally-Assisted Cracking of Martensitic Stainless Steel Octg Material in H2S-Saturated Condition at Room Temperature to Elevated Temperature

Product Number: 51319-13227-SG
Author: Yasuhide Ishiguro
Publication Date: 2019
$20.00

In martensitic stainless steel used in H2S-saturated condition SSC is regarded as a main concern rather than SCC in material selection for each specific well condition. In this paper by adding hydrogen embrittlement results at elevated temperature environmentally-assisted cracking (EAC) data of SSC and SCC for are reported by using autoclave-based test results. The test condition is based on (1)temperature of 24C(75F) to 200C(392F) (2)20% and 5% NaCl solution (3)actual YS@in-situ as applied stress in four-point-bend-beam specimens (4)pH3.0@in-situ to pH5.0@in-situ which was adjusted by four factors of (a)partial pressure of 5MPa CO2 (b)partial pressure of 0.01MPa H2S (c)0.5%CH3COOH and CH3COONa addition as pH adjustment and (d)temperature.Judging from the domain maps of EAC for 13%Cr-added to 17%Cr-added martensite-based stainless steel OCTG materials the non-failure domain for each sample is limited by cracking and/or corrosion rate. In terms of cracking as testing temperature is higher each material has higher cracking-resistant. More precisely no SSC (SCC) happens anymore at the higher temperature than SSC (or SCC) begins not to occur when an autoclave test was carried out by elevating temperature from room temperature (24C 75F). In terms of corrosion rate it tends to have the higher value when an autoclave test is carried out at the higher temperature. The stability of passivation and protective surface layer on each stainless steel are related to the resistance for these two parameters. Higher-alloyed martensite-based stainless steel has better performance in both cracking and corrosion rate. In addition it was found that martensitic stainless steel do not have the specific cracking-susceptible temperature range at around 80C to 100C (175F to 210F) temperature which duplex stainless steel are said to specifically fail.

Picture for Environment-Assisted Cracking and Corrosion Fatigue of Aircraft Aluminum Alloys in Corrosive Atmospheres
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Environment-Assisted Cracking and Corrosion Fatigue of Aircraft Aluminum Alloys in Corrosive Atmospheres

Product Number: 51319-13350-SG
Author: Brandi Clark
Publication Date: 2019
$20.00

Environment-assisted cracking and corrosion fatigue of aluminum alloys in corrosive atmospheres present significant maintenance and safety issues for aircraft. It is well known that these cracking phenomena result from the combined effects of environment mechanical loads and material properties. The service life of an aircraft structure is dependent on various stages of degradation associated with the deposition of aggressive contaminants formation of corrosion damage crack nucleation and crack propagation. Each of these stages affect the service life of a structure and are dependent on a large number of time dependent factors including environmental severity mechanical loading and protective properties of coatings. This work focuses on quantifying in situ the influence of environmental conditions including cyclic humidity and salt chemistry on the incubation nucleation and growth of cracks under both static and dynamic loads. Two test systems are used in atmospheric corrosion tests to continuously measure crack length and estimate crack growth rates. An instrumented double cantilever beam sample and loading fixture is used to obtain short crack measurements and a hydraulically actuated four point bend sample is used for long crack measurements. The atmospheric testing demonstrates strong hysteresis for aluminum alloy (UNS A97075) crack growth rate with respect to humidity during wetting and drying. The humidity dependence of crack growth rate is a strong function of the hygroscopic properties of the salts and salt mixtures. The maximum crack growth rates are observed below the deliquescence relative humidity during the drying stage of an atmospheric test cycle. Other factors that influence initiation time and crack growth rate including galvanic couples crevices and protective coatings are being investigated.