A Metallurgical Characterization and Assessment of SMA, GMA, EB, and LB Welds of HY-130 Steel.
Abstract
HY-130 weldments of 6.35 and 12.7 mm thickness were fabricated by shielded metal arc (SMA), gas metal arc (GMA), electron beam (EB), and laser beam (LB) processes. Hardness explorations and metallographic examinations were made of the weld metal and heat-affected zone (HAZ) of the weldments. EB and LB weldments showed perceptibly higher weld metal hardnesses and steeper hardness gradients in the HAZ than corresponding SMA and GMA weldments. SMA and GMA welds consisted of a large percentage of acicular ferrite with smaller amounts of bainite and martensite; EB and LB welds comprised mostly martensite and a small percentage of bainite. Strain hardening exponent values for SMA, GMA, and LB welds were appreciably higher than the values obtained for EB welds and the base metal. As indicated by dynamic tear (DT) tests run at room temperature, the weld joint specimens exhibited mostly plane stress (slant) fracture. LB specimens disclosed a fracture toughness not only higher than that of the other weld joints but also comparable to the fracture toughness of the base metal. LB weld joint fracture energy values were found to be 94.5 to 97.7 percent of those of the base metal. Metallurgical conditions and variables that promote susceptibility to cold cracking were found to be more prevalent in SMA and GMA weldments than in EB and LB weldments. Inspection of the DT fractures disclosed a small to moderate amount of porosity in SMA and GMA weldments, the presence of cold shuts (incomplete fusion) in EB weldments, and some evidence on a minor scale of cold shuts and hydrogen embrittlement in the LB weldments.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1977
- Accession Number
- ADA047418
Entities
People
- E. A. Metzbower
- J. Stoop
Organizations
- United States Naval Research Laboratory