The influence of tempering temperature on small fatigue crack behavior monitored with surface acoustic waves in quenched and tempered 4140 steel

Journal Article · Sat Jul 01 00:00:00 EDT 1989 · Metallurgical Transactions, (Section) A: Physical Metallurgy and Materials Science; (USA)

DOI:https://doi.org/10.1007/BF02647408· OSTI ID:5308710

London, B ^[1]; Nelson, D V ^[2]; Shyne, J C ^[3]

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1. McDonnell Douglas Research Labs., St. Louis, MO (USA)
2. Stanford Univ., CA (USA). Dept. of Mechanical Engineering
3. Failure Analysis Associates, Palo Alto, CA (USA)

The authors describe their investigation of small surface fatigue crack growth in specially designed cantilevered bending samples of high-purity 4140 steel quenched and tempered to various strength levels. Tempering temperatures of 200 {sup 0}C, 400 {sup 0}C, 550 {sup 0}C and 700 {sup 0}C were used to produce a range of yield strengths and microstructures. Crack propagation and crack closure were monitored with a surface acoustic wave ultrasonic technique. The small crack results were compared to those of long cracks in compact tension samples. Small cracks in the 200 {sup 0}C and 400 {sup 0}C tempers grew at {Delta}{Kappa} levels above their long crack thresholds. Small cracks in the 550 {sup 0}C tempers grew at {Delta}{Kappa} levels slightly below the long crack threshold. The surface cracks in the 700{sup 0}C temper grew well below the long crack threshold showing the small crack effect.

• OSTI ID: 5308710
• Journal Information: Metallurgical Transactions, (Section) A: Physical Metallurgy and Materials Science; (USA), Vol. 20A:7; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
STEELS
CRACK PROPAGATION
ACOUSTIC MONITORING
FATIGUE
MICROSTRUCTURE
TEMPERATURE EFFECTS
ALLOYS
CRYSTAL STRUCTURE
IRON ALLOYS
IRON BASE ALLOYS
MECHANICAL PROPERTIES
MONITORING
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies
360104 - Metals & Alloys- Physical Properties
420500 - Engineering- Materials Testing