Improved Fracture Toughness and Fatigue Characteristics of Electroslag Welds

DTFH61-83-C-00112This project was designed to increase the reliability, integrity and mechanical behavior of electroslag welds in type A36 and A588 steel alloys. The parameters developed in this program utilized a narrow gap and a consumable plate guide tube in combination with reduced voltages and higher welding currents. This reduced heat input, increased welding speed, and also reduced weld imperfection tendency. Alloy additions, nickel and molybdenum, develop an acicular weld metal tough microstructure. To minimize heat input, alloy additions were made through a tubular alloyed powder-containing wire. Charpy impact toughness data exhibited uniformly high weld metal toughness. Heat affected zone impact toughness exhibited wide variations and was sensitive to test location. The lowest impact toughness was within approximately 1 mm of the fusion boundary and was approximately equivalent to the zone 2 impact toughness requirements. Full-thickness fracture toughness data were comparable to base metal when the optimized procedures and alloying conditions were utilized. Full thickness toughness data did not show wide variations in the heat affected zone. Hence, Charpy impact toughness assessment without standardized test locations and relative to full thickness data may not be the best method to assess toughness. None of the 12 electroslag welds evaluated under fatigue conditions developed cracks within the test conditions studied. These data suggest that sound electroslag welds in the absence of weld imperfections more than meet AASHTO fatigue requirements for category B weldments

Industrial Field Trials of Oregon Graduate Institute-Developed Electroslag Welding Technology

DTFH61-86-X-00119The primary objective of this program was to demonstrate that the Oregon Graduate Institute (OGI)-developed electroslag welding (ESW) technology cay be successfully implemented in commercial fabrication shops. Consequently, opportunity was provided to evaluate the transferability of ESW technology and to develop additional ESW mechanical property data from commercially fabricated weldments

Repair of Process-Related Defects in Electroslag Welding

DTFH61-86-X-00119The primary objectives of this program were to develop a welding procedure for repair of electroslag weldments and to determine if repair welding influenced the fatigue strength of electroslag weldments. Integral to this effort was the identification of the most likely types of defects, their causes, and the potential for effective repair. The electroslag welding (ESW) process is capable of producing a higher volume of defect-free weld deposit than other processes used for joining structural steel. When defects do occur, however, ESW is not well-suited for use as a repair process since it is limited to vertical position, single-pass, full-thickness welding