Effect of corrosion on mechanical properties of the joining of materials

The effect of corrosion behavior in critical environmental conditions on the mechanical properties of composite/metal materials joints was investigated by immersing metalic materials into 5wt% hydrochloric acid solutions. The current study was carried out on a single lab joint with a total thickness of 4mm; thus, a destructive test was undertaken to investigate the corrosion behavior induced degradation of mechanical properties followed by Scanning electron microscope analysis (SEM). The joined specimens were examined under both non-corrosive and corrosive environmental conditions. Moreover, the Taguchi analysis of experimental data for maximizing the required output is carried out to validate the impact and significance of input factors. Experimental results have shown that the weight losses of the mild steel and aluminum materials are 7.45% and 16.7%, respectively, in 5% wt hydrochloric acid after three weeks. The corrosive environment affected the strength of the joints and obtained an early failure on the joint region that leads to a reduction on the strength of the materials by almost 15% compared to the non-corroded joint. The joining of non-corroded similar steel obtained the highest maximum stress among all other specimens, where the maximum recorded stress was 140.5MPa as compared to 125MPa for corroded specimen. Furthermore, the mode of failure and hardness tests were obtained and analyzed for all specimens. A significant reduction in the hardness of the materials after exposure to the HCl acid was observed

Severity of corrosion under insulation (CUI) to structures and strategies to detect it

This review paper considers the research conducted in the past 30 years in the field of corrosion under insulation (CUI). CUI is a significant challenge in many industries for reasons of high cost and risk because it proceeds undetected under insulation. CUI is an unavoidable problem which may potentially cause personnel injury or even fatalities. Presently, CUI counts for as much as 40 to 60% of pipeline-repairing cost. The use of coating under the insulation has been shown very efficient in the mitigation of CUI. Moisture and ion penetration, particularly chlorides, through the insulation and coating may produce stress corrosion cracking of austenitic stainless steels. The process of applying insulating materials on metal surfaces and the precautions that need to be taken are explained. Beside visual inspection, techniques such as neutron backscatter, capacitive imaging and pulsed eddy current can be used to detect the presence of CUI. The strength and limitations of the available commercial detection techniques are evaluated. A comprehensive list of industrial standards dealing with CUI is provided.Scopu