Corrosion of hot end automotive exhaust components

Abstract

Purpose -To evaluate the corrosion resistance of four different stainless steels often employed in hot end exhaust components. Design/methodology/approach -This paper evaluated the outcomes of the hot salt test and the cyclic oxidation test on four different stainless steels, used as hot end exhaust components. The specimens were analyzed by means of SEM for surface changes and the weight loss was considered. Findings -The general corrosion rate and pitting resistance under all the test conditions for hot end exhaust components indicated that 434 was by far the most corrosion resistant alloy, followed by 1.4509 and 321, and lastly 304 was the least corrosion resistant. In general, the ferritic stainless steels, especially 434, outperformed the austenitic ones under all the test conditions. Practical implications -The comparison of the corrosion resistance and rate, between the frequently used ferritic and austenitic stainless steels used in the exhaust system, gave a clear indication that the ferritic steels will provide prolonged service and this could be beneficial information to the manufacturers. Originality/value -A new approach to summarise the materials' behaviour and their relative performance in the tests performed was developed. This proposed summary of a number of corrosion indicators could serve as a relative guide to alloy selection for use in hot end automotive exhaust systems for both manufacturers and users.

Effect of Nb on the Performance of 409 Stainless Steel for Automotive Exhaust Systems

“…The complex working environment in automotive exhaust systems has strict requirements for the performance of materials. At the hot end, the working temperatures of exhaust system parts such as exhaust manifold, front pipe, and catalytic converter are usually higher than 600 °C, and thus good heat resistance is required for the materials . Additionally, at the cold end of the exhaust system, the corrosive condensate of exhaust gas could cause the occurrence of pitting perforation in muffler .…”

Influence of filler wire composition on weld microstructures of a 444 ferritic stainless steel grade

“…These last ones are also called "superferritic" due to the high stability of ferrite at all temperature. Miyasaki et al (2003) and later Potgieter et al (2007) observed that addition of molybdenum improved drastically resistance to cyclic oxidation as well as high temperature strength of the steel.…”

CHAPTER 6 Development of SOFC Interconnect Stainless Steels

“…The AISI 444 is also stabilised by titanium but additionally alloyed with molybdenum by about 2 wt.%. It was reported that the molybdenum addition could help increase the pitting corrosion resistance [41], the stress corrosion resistance [42], the cyclic oxidation and high temperature strength of the steel [43][44][45]. However, as will be shown in Section 6.6, the molybdenum addition could form Fe-Mo intermetallic compound, which deteriorates the scale adhesion at high temperatures [36].…”