Formability of new high performance A710 grade 50 structural steel.

Details

• Creators:
  Vaynman, Semyon ; Fine, Morris E. ; Hahin, Christopher
• Corporate Creators:
  Northwestern University (Evanston, Ill.). Dept. of Materials Science and Engineering
• Corporate Contributors:
  United States. Federal Highway Administration ; Illinois. Dept. of Transportation
• Subject/TRT Terms:
  • Weathering steel
  • High strength steel
  • Bend tests
  • Tension tests
  • Yield strength
  • Thickness
  • Ductility
  • Forging
  • Structural steel
• Publication/ Report Number:
  FHWA-ICT-14-002 ; ICT-14-002 ; UILU-ENG-2014-2002
• Resource Type:
  Tech Report
• Geographical Coverage:
  Illinois
• Corporate Publisher:
  Illinois Center for Transportation
• Abstract:
  This project compared the formability of modified ASTM A710 Grade B50 ksi yield strength steel, jointly developed by ; Northwestern University and the Illinois Department of Transportation, with ASTM A606 Type 4 weathering steel used in Illinois ; and many other states for sign and signal structures, light poles, and other highway structures. ASTM E290 Type 1 free-bend ; 180° guided-bend test was used to evaluate formability, with side clearances as per ASTM E190. Bend and tensile specimens ; were cut in longitudinal and transverse directions from plates and sheets of numerous thicknesses (from 0.38" down to 0.10" ; thick). Mandrels of three diameters (0.25", 0.313", and 0.375") were used, each having a rounded nose with radius of bend ; equal to ½ of the mandrel diameter. All specimens of A710 and A606 steels of all thicknesses passed the guided-bend tests. No ; cracks, side tears, or fractures were observed. Tensile tests showed excellent ductility in both longitudinal and transverse rolling ; directions, making the modified ASTM A710 steel very suitable for use in sign and signal structures, light poles, and highway ; structures, along with structural tubing and other applications requiring weathering steel sheets and plates. ; Comparable A606 Type 4 steel had a yield strength range of 65 to 73 ksi and an ultimate tensile strength range of 79 to ; 89 ksi. The elongation to failure for the A606 steel sheets was in the range of 41% to 49%, averaging 43% ± 2.5% based on a 1" ; gage length. The microstructure of A606 steel is primarily ferrite with a limited amount of pearlite. The grain size of A606 in ; thinner plates was much smaller; grains were more rounded in thicker plates. ; Two heats of modified A710 Grade B steel were tested. Variations in mechanical properties were a function of steel ; composition, hot-rolling procedures, and thickness of the plates or sheets. In the first heat, yield strength varied in a range of 48 ; to 119 ksi, and tensile strength ranged from 64 to 119 ksi. The variation in the strength in the first heat was most likely caused ; by excessive section reduction during hot-rolling. The microstructure of the A710 steel was fine-grained ferrite and was ; significantly smaller than the A606 steel grains of similar thickness, which accounted for the higher strengths of the A710 steel ; in the first heat. Some bands of pearlite and fine-grained ferrite were observed in the modified A710 sheets, but did not affect ; the formability of the steel. ; Copper, nickel and manganese contents were decreased and better rolling procedures were used in the second heat, which ; had a uniform 49 to 56 ksi yield strength range. The second heat also had a uniform yield to tensile ratio of 0.74, high ductility ; and formability, making this alloy a very attractive weathering steel for many transportation and structural applications. An ; optimized 50 ksi minimum yield strength composition with an ASTM G101 index of 6.0 or more was developed for A710 sheet ; steel, and is proposed for general use in transportation and other construction applications.
  More +
• Format:
  PDF
• Funding:
  R27-106
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/27028/dot_27028_DS1.pdf
• File Type:
  [PDF - 3.40 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:c14a5cb3cdb0ec8721df6590c92a1dea079d65542566776177e827061a49d6b9