Professor Emeritus of Mechanical Engineering, Tohoku University, Aramaki, Sendai,
Director, The Japan Steel Works, Ltd., Tokyo,
Manager, National Research Institute for Metals, Tokyo,
General manager, Research Laboratory, The Japan Steel Works, Ltd., Muroran,
Pages: 24 Published: Jan 1988
Round robin test programs of the tentative test procedure for the determination of the threshold stress-intensity factor KISCC were conducted under the auspices of the 129th Committee, Japan Society for the Promotion of Science. The test programs used JIS SNCM 439 (AISI 4340) steels. Thirty-one laboratories participated in these programs. Tests were carried out with both 25.4-mm (1-in.)-thick bolt loaded wedge-opening-loading (WOL) specimens and 25.4 by 25.4-mm cantilever beam (CB) specimens in a 3.5% sodium chloride solution of distilled water.
The results of the round robin test programs showed some informations to standardize the KISCC testing procedure. For valid KISCC values to be obtained, the test must last 7000 h for a WOL specimen and 4000 h for a CB specimen. In the WOL tests, the final crack length and width ratio af/W of a specimen must be smaller than 0.8. An elastic bolt analysis of WOL specimens was recommended to obtain the valid KISCC values and the good relationship between da/dt and KI. In the CB tests, the estimated KISCC value coincided well with that in the WOL tests when at least six CB specimens were used. Slight effect of crack front curvature, test temperature, and pH of the solution on the variance of the KIf values was observed.
With these test results, the KISCC testing procedure was standardized by the Committee and entitled “Standard Test Method for Threshold Stress Intensity Factor KISCC in Stress Corrosion Cracking.”
environmental testing, fracture mechanics, stress corrosion cracking, stress intensity factor, subcritical flaw growth, test technique, evaluation
Paper ID: STP23279S