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Creep deformation and damage evaluation of service exposed reformer tube

IR@NML: CSIR-National Metallurgical Laboratory, Jamshedpur

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Title Creep deformation and damage evaluation of service exposed reformer tube
 
Creator Roy, Nilima
Raj, A
Roy, B N
Ray, Ashok K
 
Subject Metallurgy
 
Description This paper aims at studying the creep deformation behaviour and quantifying creep damage of similar to 11 years service exposed primary hydrogen reformer tube made of HP40 grade of steel in a petrochemical industry, in terms of Kachanov's continuum damage mechanics model (K model) and Bogdanoff model (B model) based on Markov process. Hot tensile, conventional creep deformation under identical test conditions, optical microscopy and fractography were extensively carried out. The as received tubes did not possess any sign of degradation including voids or creep cavitations and decarburisation. There was indeed loss of tensile strength from room temperature to 870 degrees C for the bottom portion of the tube due to aging and overheating. Accumulation of damage due to creep has been quantified through microstructural studies in terms of two damage parameters A and A*. Experimental scatter observed in creep deformation and creep strain rate curves of the material at 870 degrees C and at various stress conditions, is probably due to scatter in creep cavitations/voids and also due to variation in the mode of fracture in top as well as bottom portion of the tube. From statistical point of view, Weibull distribution pattern for analysing probability of rupture due to void area, shifts with increase in true strain towards the higher population of void. The estimation of average time to reach a specific damage state from K model and B model is in close agreement with that of experimental data and can describe the sudden changes of the creep damage in the tertiary region as well.
 
Publisher MANEY PUBLISHING, STE 1C, JOSEPHS WELL, HANOVER WALK, LEEDS LS3 1AB, W YORKS, ENGLAND
 
Date 2015-04
 
Type Article
PeerReviewed
 
Relation http://apps.webofknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=R2guq97BWyY5sM9LYpE&page=1&doc=39&cacheurlFromRightClick=no
http://eprints.nmlindia.org/7291/
 
Identifier Roy, Nilima and Raj, A and Roy, B N and Ray, Ashok K (2015) Creep deformation and damage evaluation of service exposed reformer tube. Canadian metallurgical quarterly, 54(2) (IF-0.510). pp. 205-222.