Investigation of mechanical properties and chemistry within a thick MnMoNi submerged arc weldment

The mechanical properties and chemical analysis of a 12-inch thick MnMoNi automatic submerged arc weldment have been characterized. The material investigated was manufactured during the normal fabrication of a reactor pressure vessel and was made with two weld wire-flux combinations. This work was conducted to determine what variations in mechanical properties and chemical analysis are present in a normal strength weldment. The work was funded by Electric Power Research Institute (EPRI) Contract RP232-3-0, ''Determining Fracture Toughness Properties of Reactor Vessel Forgings, Weldments, and Bolting Steels.'' The mechanical properties--tensile, impact, drop weight NDT and static and dynamic fracture toughness--were determined at five locations through the thickness of the weldment--outside surface (of the vessel), 1/4 T, 1/2 T, 3/4 T, and inside surface. The tensile properties through the thickness vary to a minor degree and are similar for the two wire-flux combinations. The best impact properties occur at 1/2 T, 3/4 T, and inside surface positions involving one wire-flux combination. The static and dynamic fracture toughness properties at RT/sub NDT/ + 600F do not vary appreciably throughout the weldment thickness. The toughness properties seem to be insensitive to acceptable variations in weld-wire chemistry. A very comprehensive survey of the chemical analysis of the weldment was made using spectrographic and electron microprobe analysis techniques. The results of this survey indicate the weld metal has lower concentrations of C, Cr, Mo, Sn, V, Ni, and higher concentrations of Mn, P, S, Si, and Cu than the base metal. The analysis results of the electron microprobe technique generally agree with those of the spectrographic technique