Activated diffusion brazed repair for IN738 hot section components of gas turbines

The wide-clearance activated diffusion brazing (ADB) techniques with variou s brazing alloys, namely DF4B and Nicrobraz 150 were applied to restore wor n areas of IN738 components. In this study, the microstructure of an ADB jo int and the results of thermal cyclic tests as well as tensile tests within the temperature range of from 25 to 980 degreesC were investigated and dis cussed. The results of the tensile tests showed that ADB specimens brazed b y 40 wt.% DF4B at 1190 degreesC exhibited 85% tensile strength of the IN738 base materials at room temperature and retained the same strength as that of the base material at 980 degreesC. However, the ductility of the ADB spe cimens with both brazing alloys was reduced. The results of cyclic-oxidatio n tests showed that ADB specimens with Nicrobraz 150 as the brazing alloy d ecayed after 150 cycles. However, the ADB specimens with DF4B had no obviou s weight change until 205 cycles. (C) 2001 Elsevier Science B.V. All rights reserved.