Biography - Thailand Automotive Institute

Materials and Corrosion in Exhaust Gas Pipe
Associate Professor Gobboon Lothongkum, Dr.-Ing.
Department of Metallurgical Engineering,
Faculty of Engineering, Chulalongkorn University
E-mail: gobboon.l@chula.ac.th
Abstracts
Exhaust gas consists of hydrocarbon, nitrogen oxide (NOx), carbon monoxide, hydrogen, carbon dioxide,
excess oxygen, water vapor, nitrogen and carbon. Automotive exhaust gas temperature decreases form about
1,000C at the manifold to be approximately 100-200C at the tail end pipe. To fabricate exhaust gas pipe, the
materials must be deformed, bended and welded. During use, it is at high temperature, in the exhaust gas
atmosphere containing water vapor and under vibration load. The materials used must perform many good
properties such as deformability, bending, weld ability, and high temperature oxidation resistance as well as
corrosion resistance especially intergranular corrosion resistance of weldment. Stainless steel is one of the
chose materials for exhaust gas pipe because those properties of stainless steels are good enough. This article
reviews the development of stainless steel for exhaust gas pipe in the view point of intergranular corrosion
resistance of weldment due to the chromium carbide precipitation at the grain boundary of weldment during
500-900C. This results in chromium depleted zone at the grain boundary. Consequently, the intergranular
corrosion resistance of weldment decreases. In addition, the intergranular corrosion can initiate the fatigue
corrosion or corrosion under vibration load of weldment.
Biography
Dr. Gobboon Lothongkum, is an associate professor and a member of the Innovative
Metals Research Unit, Department of Metallurgical Engineering, Faculty of
Engineering, Chulalongkorn University. He received Dr.-Ing. Degree from University
of the Federal Armed Force Hamburg, Germany in 1994 and the International
Welding Engineer Certificate of the International Institute of Welding in 2006 from
SLV Munich. He joined the research on AISI 409LTi stainless steel with the
Kawasaki Steel Corporation (Now is JFE Steel Corporation) in 1998. His articles in
the international journals listed in ISI data base include corrosion of metals and
alloys, welding of metals, stainless steels and high temperature materials.
Working address: Department of Metallurgical Engineering, Faculty of Engineering,
Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
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