Effect of coating on induced thermal and tensile stress on the fracture of exhaust pipe material

• Thermal treatment of steel causes microstructural changes & different coating rates.
• Thermal and tensile stress causes formation of anode/cathode site on steel samples.
• Tensile stress changes grain orientation and dislocation barrier built up in steel.
• Thermal treatment at 850 °C enhanced the corrosion performance of steel in seawater.
• Further enhancement against corrosion failure was achieved by zinc coating on steel.

Engineering materials disintegrate in divers’ ways that can later result in service failure. The service life of automobile silencer depends typically on the heat generated through the pipe and on the variability of harsh conditions component is exposed. Regular use and long time in service of any part could result into unexpected buildup of stresses that can result in ruinous failure or crack of structure. Automobile exhaust pipe is made up of steel; four representative samples of this material were subjected to thermal cycles and tensile loading with the aim of inducing stress. Metallic zinc was used to coat the stressed steel samples for the purpose of arresting cracks before subjecting them to seawater environment to check their electrochemical response. Experimental results indicated that the zinc coated steel samples (both thermal and tensile stressed) displayed anti-corrosion properties resisting fret cracking whereas the uncoated induced thermal and tensile stressed samples performed less. Coating offered some restrictions to the failure of engineering materials subjected to induce thermal and tensile stresses; this is attributed to the ability of zinc acting as a sacrificial anode to steel in the chloride environment.