Corrosion mechanism of automotive mufflers was investigated by SEM(scanning electron microscope)and XRD(X-ray diffractomer)analysis.409Land newly developed 439Msteels were evaluated in terms of condensate corrosion tests for 5periods,10periods and 20periods separately.The relative lifetimes of 409Land 439Msteels were predicted according to the extreme value analysis method and pitting corrosion models.Modelling studies demonstrated that the predicted relative lifetime of 439Mferrite stainless steel is 6.8times that of 409Lsteels.The extreme value analysis method was also successfully used in the road test.The estimated maximum corrosion depth of the 439M muffler is 0.55mm.
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