Experimental Research On Failure Modes Of High Temperature Synthetic Ammonia And Reformer Furnace Coil

macrocracks were found in the welded joints of ascending tube （thematerial is Incoloy800H）and carbon steel cylinder in the operation of one-stage converter of synthetic ammonia equipments owned by CLTH Co., Ltd.Several new cracks arose after repairing of welded joint.In order to confirm the position of cracks and analyze the producingcauses for cracks based on crack features, the authors make a failure analysisof one section of disable furnace tube provided by CLTH Co., Ltd. The maintasks of this thesis are as follows:1、Finding out defects and their positions of welded joint in furnacetube by non-destructive test involved dye penetration test and TOFD test,which also laid a ground for subsequent work of failure analysis.2、Making circumferential division of welded joint depended on defectedresult; choosing specimens with macroscopical failure feature from specimensof disable furnace tube to carry out metallographic experiment after theprocess of cutting and polishing; finding the possible cause of defects in termsof metallurgical structure by analyzing metallographs which had been taken.3、Making SEM and X-ray energy spectrum analysis of specimens on thebasis of metallographic experiment；explaining the causes of crack and defectformation in the welded joints from the study of fractography and changes of material composition.4、Making a numerical simulation of temperature and stress fields forwelded transition joints of furnace tubes with ANSYS software.The research results of this paper have a certain theoretical and practicalsignificance for the study of failure modes of dual-phase steel welded joints inhigh temperature environment.