Failure analysis of radiant tube burners in continuous annealing line (CAL) of an integrated steel plant

Failure analysis of radiant tube burners (ACI HK 40 with composition ∼25 wt.% Cr, ∼20 wt.% Ni) removed from a continuous annealing line (CAL) of a cold rolling mill (CRM) of an integrated steel plant was performed using optical microscopy (OM), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and microhardness measurements. Studies revealed that the failures were mainly attributed to combined influences of creep and carburization-assisted localized oxidative attack. A suitable heat-resisting cast austenitic stainless steel was identified as a candidate alloy to replace the previously used ACI HK 40 alloy. © 2011 ASM International.