Fatigue of bainitic 2 1/4 Cr-1 Mo steel weldments at 482/sup 0/C
Low-cycle fatigue tests were performed on specimens machined from weldments of 2 1/4 Cr-1 Mo steel. Section thicknesses were in the range 150 to 300 mm, and welds were produced by the submerged arc (SA) and the narrow-groove hot-wire gas tungsten arc (NG-HW-GTA) processes. Test specimens included hourglass and uniform-gage specimens machined from base metal, weld metal, or combinations including the heataffected zone (HAZ) in the testing section. Most specimens were postweld heat treated for 28 h at 690/sup 0/C before testing. Poor fatigue behavior was observed in some weldments because of strain concentrations in samples that contained HAZ and porosity in samples that were entirely weld metal. Porosity was much greater in the NG-HW-GTA welds than in the SA welds. The most severe HAZ and porosity effects were equivalent to a factor of two in strain concentration. Time-dependent effects were examined in a few tests by introducing hold periods up to 1 h at the compressive or tensile strain limit of each cycle. Although such effects did reduce the fatigue life, the reduction was no more severe than that caused by the strain concentration in the HAZ or by the porosity. The longest hold-time tests showed some internal cavitation; however, most failures in sound material were produced by a surface oxide cracking mechanism, which has been extensively examined in annealed 2 1/4 Cr-1 Mo steel.
- Research Organization:
- Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
- OSTI ID:
- 6316386
- Report Number(s):
- CONF-840647-; TRN: 85-000205
- Journal Information:
- Am. Soc. Mech. Eng., (Pap.); (United States), Vol. 84-PVP-57; Conference: ASME pressure vessel and piping conference, San Antonio, TX, USA, 17 Jun 1984
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHROMIUM-MOLYBDENUM STEELS
FATIGUE
TEMPERATURE EFFECTS
WELDED JOINTS
ARC WELDING
BAINITE
CAVITATION
COMPRESSION
CRACK PROPAGATION
FAILURE MODE ANALYSIS
HEAT TREATMENTS
HIGH TEMPERATURE
MATERIALS TESTING
OXIDES
POROSITY
SAMPLING
STRAINS
THICKNESS
TIME DEPENDENCE
ALLOYS
CHALCOGENIDES
CHROMIUM ALLOYS
CHROMIUM STEELS
DIMENSIONS
FABRICATION
IRON ALLOYS
IRON BASE ALLOYS
JOINING
JOINTS
MECHANICAL PROPERTIES
OXYGEN COMPOUNDS
STEELS
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
TESTING
WELDING
360103* - Metals & Alloys- Mechanical Properties