Effect of microstructure on fatigue crack growth in duplex ferrite-martensite steels

Technical Report · Tue Jun 01 04:00:00 EDT 1982

OSTI ID:6880245

Wasynczuk, J A

Monotonic tensile and fatigue crack growth tests have been performed on AISI 1018 and Fe/2Si/0.1C steels with duplex ferrite-martensite (DFM) microstructures. The effect of microstructure on mechanical properties was examined. Two distinct martensite distributions were produced in AISI 1018 DFM. The primary differences between the two were ferrite and martensite particle sizes. It was found that tensile fracture was sensitive to both martensite distribution and volume fraction. For a given volume fraction of martensite, large particle sizes increased strength but drastically reduced ductility. The volume fraction of martensite influenced tensile properties according to the rule of mixtures. Threshold stress intensity ranges for fatigue crack growth in AISI 1018 DFM were found to be unaffected by the distribution or the volume fraction of martensite. Mid-growth range fatigue crack growth rates in AISI 1018 DFM were increased when particle sizes were large. The increased crack growth rates were attributed to crack extension by cleavage fracture in ferrite. The Fe/2Si/0.1C DFM alloy was found to have a considerably higher fatigue threshold stress intensity than AISI 1018 DFM of comparable strength. The greater fatigue threshold stress intensity in Fe/2Si/0.1C DFM was attributed to crack closure effects. 18 figures, 4 tables.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6880245
• Report Number(s): LBL-15110; ON: DE83003715
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CARBON ADDITIONS
CRACK PROPAGATION
CRYSTAL STRUCTURE
DATA
ELECTRON MICROSCOPY
EXPERIMENTAL DATA
FATIGUE
FRACTURE PROPERTIES
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
MARTENSITE
MECHANICAL PROPERTIES
METALLOGRAPHY
MICROSCOPY
MICROSTRUCTURE
NUMERICAL DATA
PARTICLE SIZE
SIZE
STEELS
TENSILE PROPERTIES