Analysis of the Low Cycle Fatigue Behavior of DP980 Steel Gas Metal Arc Welded Joints

Metals

César M. Gómora¹  Ricardo R. Ambriz¹  Walter F. González-Zapatero¹  Juliana G. Rosado-Carrasco¹  Christian J. García¹  David Jaramillo¹ 

[1] Instituto Politécnico Nacional CIITEC-IPN, Cerrada de Cecati S/N Col. Sta. Catarina, Azcapotzalco, Mexico City 02250, Mexico;

关键词: DP980 steel sheet;    low cycle fatigue;    gas metal arc welding;    heat affected zone;    tempered martensite;   

DOI  :  10.3390/met12030419

来源: DOAJ

【 摘 要 】

Dual phase (DP) steels have high strength, while maintaining outstanding elongation capacities. This is possible using a well-controlled thermomechanical process that produces a perfect phase combination in the DP microstructures. However, automotive makers are required to weld the DP steels, which generates a soft zone in the microstructure. In this work, 1.6 mm-thick DP980 steel sheets were welded by gas metal arc welding process to analyze the response of the welded soft zone to cyclic loading conditions. Conducted macrographic and metallography analyses revealed good quality in the appearance of the welded joints, with a complete fusion of the DP980 joint and without the presence of discontinuities. Low cycle fatigue tests of the DP welded joints were conducted under a constant amplitude strain control mode. The welded joints experienced a fatigue life reduction with respect to the DP980 steel of ~16% at strain amplitudes of 0.2, 0.3, and 0.4%. For strain amplitudes larger than 0.6%, the fatigue life of the welded joint was reduced by 39%. Weld thermal cycles combined with metallography analysis indicated that a tempered process of the martensite during the welding was responsible for the soft-zone formation and the poor fatigue response.

【 授权许可】

Unknown