Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Material characterization and analysis of critical failure in EGR component for Diesel pickup trucks
Submission Author:
Felipe dos Anjos Rodrigues Campos , MG
Co-Authors:
Elberton Santos Castro, Felipe dos Anjos Rodrigues Campos, Maksym Ziberov, André Rezende de Figueiredo Oliveira
Presenter: Felipe dos Anjos Rodrigues Campos
doi://10.26678/ABCM.COBEM2021.COB2021-1727
Abstract
Current environmental concerns press the automotive industry to produce more efficient engines, as exemplified by the exhaust gas recirculation system (EGR) in Diesel vehicles. Part of the exhaust gases is reintroduced in the combustion chamber mixed with the intake air. However, the hot gasses must be previously cooled down indirectly in a radiator, through which circulates water from the engine cooling system. The combination of high temperatures in the radiator tubes and possible presence of residual stress from the assembly processes might promote crack formation, which may causes serious leakages. This work was based on the failure analysis of a recurrent leakage problem in the EGR radiator of Diesel pickup trucks. A case study was conducted with damaged parts, which were examined by dye penetrant inspection and leakage test with water at 1 bar and 100 °C. Small cracks were observed in the joints of the tubes with the radiator baffles, likely due to crevice corrosion. Pit corrosion was also verified along the tubes, in the form of small holes visible only by optic microscopy. Scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and hardness tests were used to characterize the stainless steel alloys of the EGR radiator. The corroded surface presented high content of adhered aluminum oxide, usually formed by the reaction contaminated water and metal parts. The chemical composition and hardness of the tubes also indicates the application of stainless steel of series 300, but without the minimum amount of nickel recommended by the ASTM standards. Based in the results, it was suggested for the manufacturer to change the type or acquisition source of the stainless steel in the tubing, in order to reduce maintenance events and improve brand reliability.
Keywords
failure analysis, Exhaust gas recirculation, dye penetrant test, stainless steels, corrosion
