Very high cycle fatigue properties of bainitic high carbon–chromium steel

✍ Scribed by H. Mayer; W. Haydn; R. Schuller; S. Issler; B. Furtner; M. Bacher-Höchst

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 807 KB
• Volume: 31
• Category: Article
• ISSN: 0142-1123
• DOI: 10.1016/j.ijfatigue.2008.09.001

✦ Synopsis

Fatigue properties of bainitic 100Cr6 (SAE 52100, JIS SUJ2) steel are investigated in the high cycle and very high cycle fatigue (VHCF) regime. Fully reversed tension-compression fatigue tests are performed with ultrasonic fatigue testing equipment. Specimens are grinded which leads to surface compression stresses and increased surface roughness. About 1/3 of the specimens failed after crack initiation at interior Al 2 O 3 À or TiN-inclusions and 2/3 failed after surface crack initiation at scratches or cavities. When inclusions are considered as cracks, failures can occur at minimum stress intensity range of 2.8 MPa m 1/2 , and maximum stress intensity range without failure is 3.3 MPa m 1/2 . Facets are visible close to the inclusion in some specimens, and the stress intensity range at the border of the facet is approximately 4.5 MPa m 1/2 . Murakami's model can well predict the endurance limit at 10 9 cycles for internal failures considering the area of the inclusion in the evaluation. Surface fatigue crack initiation can lead to failure above 10 8 cycles. When scratches are considered as cracks, minimum stress intensity range of 2.5 MPa m 1/2 can propagate surface cracks to failure. Fracture mechanics approach showed several similarities to literature results of the same material tested in tempered martensite condition.