Accession Number : AD0696057

Title :   BEHAVIOR OF MECHANICAL PROPERTIES IN NEUTRON IRRADIATED 12Ni-5Cr-3Mo MARAGING STEEL PLATE AND COMPANION WELD METALS.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Gray,R. A. , Jr. ; Hawthorne,J. R.

Report Date : 02 OCT 1969

Pagination or Media Count : 20

Abstract : Changes of Charpy-V-notch ductility and tensile strength in neutron-irradiated 12Ni-5Cr-3Mo maraging steel have been evaluated following low (less than 250F) and elevated (550 to 740F) temperature exposure. The study was performed with six heats of 1-in.-thick plate material aged at 900F for 2 and 20 hr to nominal yield strengths of 160 and 180 ksi, respectively. The long-term thermal stability of both heat-treatment conditions was investigated for the conditions of irradiation. The less than 250F and 550F irradiation performance of matching (15-5-3) and mismatching (17Ni-2Co-3Mo) TIG weld deposits maraged to 180 ksi yield strength was also assessed in this study. Changes in the general properties of the 12-5-3 maraging steel plate and companion weld metals were found to be rather small with less than 250F exposures, indicating good resistance to neutron-induced embrittlement. However, a marked deterioration of notch-ductility properties with long-term exposure at elevated temperature was revealed and traced to a nonnuclear thermal instability. The observed instability is believed to be a continuation of aging processes at temperatures well below the initial maraging temperature. Extended time-at-temperature treatments indicate that service above 550F may produce sufficient changes in properties for failure by low-energy tear. Aging treatments of 1900 to 3300 hours' duration increased the yield and tensile strengths of the 12-5-3 alloy by as much as 52.0 and 53.3 ksi, respectively, while not altering appreciably the percentage of elongation and the reduction in area. (Author)

Descriptors :   (*REACTOR MATERIALS, MARAGING STEELS), (*MARAGING STEELS, DAMAGE), (*NEUTRON REACTIONS, MARAGING STEELS), WELDS, HEAT TREATMENT, NOTCH TOUGHNESS, MICROSTRUCTURE, AGING(MATERIALS), EMBRITTLEMENT, THERMAL STABILITY, DETERIORATION, TENSILE PROPERTIES, ELONGATION, REDUCTION OF AREA, YIELD POINT, (U)YIELD POINT

Subject Categories : Properties of Metals and Alloys
      Fission Reactor Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE