An aftertreatment system is associated with an engine system.  The aftertreatment system is configured to treat and reduce oxides of nitrogen (NOx) and particulate matter present in an exhaust gas flow, prior to the exhaust gas flow exiting into the atmosphere.  In order to reduce NOx, the aftertreatment system may include a reductant delivery module, a reductant injector, a Selective Catalytic Reduction (SCR) module, and other associated components. 
The reductant injector introduces a reductant into the aftertreatment system.  The reductant includes a urea based solution.  When the urea based solution is introduced into the aftertreatment system, the aftertreatment components are exposed to free ammonia at temperatures which allow nitrogen pickup during operation.  If this pickup is uncontrolled, the properties of the aftertreatment components may change in an unexpected manner, leading to early failure of the aftertreatment components. 
U.S. Published Application Number 2014/0216423, hereinafter referred to as the '423 publication, describes an exhaust system part having a high corrosion resistance, an EGR cooler using the exhaust system part, and a method of nitriding the exhaust system part.  In the '423 publication, a chromium nitride layer is formed on the inner surface of the exhaust system part.  Further, the nitriding process of the single exhaust system part is carried out in a closed space or a furnace.  Accordingly, the nitriding process is costly and poses space constraint issues.