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Ferritic weldment of grain-refined ferritic steels for cryogenic service

Conference · · Adv. Cryog. Eng.; (United States)
OSTI ID:6009305
This paper reports the initial results of the development of a weld filler metal and multipass GTA welding process for grain-refined 9Ni steel. The weld filler metal was cast in 4.5-kg ingots of the nominal composition Fe-14Ni-O.2Ti-0.003B, homogenized, hot-rolled, and then swaged into wire of 1.6-mm diameter. The chemical compositions of the base and filler metal are tabulated and the test welding procedure is described. Among the tests that were conducted on the welds are x-ray diffraction analysis for the residual austenite content; the Charpy impact test at 77 and 4.2 K for the fracture toughness; and scanning electron fractography for the weld metal, the HAZ, and the base metal of 9Ni Charpy specimens broken at 4.2 K. The procedure for grain refinement is defined; the retained austenite volume fraction is calculated using the method proposed by Miller. The results indicate that it is possible to weld grain-refined 9Ni steel with a ferritic weld filler metal and retain good toughness at cryogenic liquid helium temperatures.
Research Organization:
University of California, Berkeley, CA
OSTI ID:
6009305
Report Number(s):
CONF-810835-
Conference Information:
Journal Name: Adv. Cryog. Eng.; (United States) Journal Volume: 28
Country of Publication:
United States
Language:
English