### STP1046V2: Swelling and In-Pile Creep Behavior of Some 15Cr15NiTi Stainless Steels in the Temperature Range 400 to 600°C

Herschbach, Kornelius

*Research scientists, Institut für Metall- und Festkörperforschung, Karlsruhe 1,*

Schneider, Walter

*Research scientists, Institut für Metall- und Festkörperforschung, Karlsruhe 1,*

Bergmann, Hans-J.

*Research scientist, INTERATOM GmbH, Bergisch Gladbach 1,*

Pages: 18 Published: Jan 1990

**Abstract**

A pressurized tube experiment (PFR-M2) is being carried out in prototype fast reactor PFR in order to determine swelling and in-pile creep of commercial (Deutsches Institut für Normung DIN 1.4970 and 12RN72) and model 15Cr15Ni austenitic stainless steel alloys. Two intermediate dimensional measurements have been performed up to now, the maximum doses achieved being approximately 52 dpa(NRT) at 420°C, approximately 40 dpa at 500°C, and approximately 27 dpa at 600°C. The combination of diameter and length measurements allowed good estimates of the stress-induced swelling by applying the Soderberg theorem. Stress-free swelling of the commercial alloys varies by about a factor of eight between the lowest and the largest swelling one. This swelling difference is attributed to a high silicon content of about 1 wt% in the former one. The stress dependence of in-pile creep is not quite linear. Swelling and in-pile creep are strongly correlated. Alloys with the most swelling also show the greatest increase in total diameter. At 420°C, the irradiation creep strains of all 15Cr15NiTi materials irradiated to the same dose level can be described by a single correlation equation with the true creep strain as a linear function of total swelling. This equation is similar to a formerly developed creep law with stress-induced preferential absorption (SIPA) and I creep terms, in which the dose was the independent variable. Up to now there exists an unsolved discrepancy in the stress exponent of the I creep term; the data analysis presented here suggests an exponent of 1½, while theory and the formerly determined correlation both suggest a value of one.

**Keywords:**

radiation, irradiation creep, swelling, stress-enhanced swelling, swelling-enhanced creep, austenitic alloys, silicon, understabilization, 1.4970, 12RN72, 15Cr15Ni, pressurized tube experiment

**Paper ID:** STP49475S

**Committee/Subcommittee:** E10.07

**DOI:** 10.1520/STP49475S

ASTM International is a member of CrossRef.