The procedure for making crack starter weld deposit on drop-weight test (DWT) specimens was altered from two passes to one pass in about 1990. The effects of some parameters of crack starter weld process on drop-weight test results were studied. Results of this study indicated that length of overlap of the second pass and height of crack starter beads were most effective on nil-ductility temperature (TNDT). When overlap length and bead height of two-pass deposit were small enough, TNDT obtained by two-pass deposit became lower than one-pass TNDT, the discrepancy being by as much as 25°C. TNDT values for 24 Japanese steels were determined using two different DWT methods, one-pass deposit and two-pass deposit having small overlap length and bead height. The difference of TNDT depending on DWT method could be seen only for high-toughness low-alloy steel base metals. For other materials (i.e., low-to-medium-toughness low-alloy steel base metals, weld metals, and high-toughness carbon steels), TNDTS by two-pass and one-pass deposits were essentially the same. For lower-toughness steels, TNDT was frequently lower than the temperature of vTcv − 33°C), and thus, the reference nil-ductility temperature RTNDT was determined from Charpy impact test results. These results can be taken as a way of interpreting the past toughness evaluations made for operating plants using the two-pass TNDT.

Ministry of International Trade and Industry, MITI Notification No. 501, Technical Standard for Construction of Nuclear Power Plants.
American Society for Testing and Materials, ASTM Standard Method E208, Conducting Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels.
American Society of Mechanical Engineers, ASME Boiler and Pressure Vessel Code, Section III.
Japan Electric Association, JEAC 4202, Drop-Weight Test Procedure for Ferritic Steels.
Ando, Y., et al., 1984, “Effect of Brittle-Bead Welding Conditions on the Nil-Ductility Transition Temperature,” ASTM STP 919.
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