|Project Name:||Optimized Welds for High-Performing Steel Grade 100 Weathering (HPS100W) Steels|
Office of Infrastructure Research and Development |
|Team:||Bridge and Foundation Engineering Team|
Infrastructure Research and Technology Strategic Plan and Roadmap|
|Project Description:||This project will determine the optimal width-to-thickness ratio of 1-inch thick high-performing steel grade 100 weathering (HPS100W) plates welded together with undermatching weld consumables.|
|Start Date:||March 14, 2011|
|End Date:||August 1, 2013|
To determine the optimized proportioning of welds, in terms of their width-to-thickness ratio, such that high-performing steel grade 100 weathering (HPS100W) steels would be fully developed using undermatched weld consumables. To be fully developed means the plate would yield prior to fracture of the weld. For plates 1.5 inches thick, the optimal width-to-thickness ratio was seven, but for 1-inch thick plates this was not optimal. Therefore, two more tests need to be conducted at width-to-thickness ratios of 12 and 16 to determine the optimal ratio for the thinner plates.
|Background Information:||In the 1990s, the Federal Highway Administration, along with the American Iron and Steel Institute and the United States Navy, set forth to create a new grade of steel termed high-performing steel (HPS). The high-performing steel grades were to have strengths in excess of 50 kilo-pound-force per square inch (ksi) yield, to be easily weldable, to be weathering, and to have toughness that would meet typical inservice environments for U.S. bridges. In the end, three grades were developed with yield strengths of 50, 70, and 100 ksi. At the time of development, the welding consumables of HPS had not matured to have the same strength levels, toughness, and weathering capabilities needed to weld the high-performing steel grade 100. One thought was to use 90 ksi undermatching weld consumables that meet toughness requirements and proportioning the weld size such that it developed internal constraint that would raise the apparent yield strength of the weld. The necessary constraint level was created by ensuring that a critical width-to-thickness ratio was met, which would cause the base metal to yield before fracture of the weld. Tests were conducted at Lehigh University, located in Bethlehem, Pennsylvania, in 2002. The university found that undermatched strength welds (90 ksi yield) could develop the higher yield strength of high-performing steel grade 100 weathering (HPS100W) parent material (greater than 100 ksi yield) provided the weld had an optimal width-to-thickness of 7 for 1.5-inch thick plates, but the optimal ratio was never identified for 1-inch thick plates. Therefore, a need exists to conduct two more tests of 1-inch thick plates at width-to-thickness ratios of 12 and 16.|
|Test Methodology:||Full-scale experimental.|
|Expected Benefits:||The expected benefit is less expensive steel bridge fabrication due to using less expensive weld consumables.|
|Deliverables:||Name: Final research report.|
Product Type(s): Techbrief
Description: The deliverable will be a final report submitted by the contracted agency to outline their experimental approach to the problem and conclusion.
Bridges and other structures|