Temperature effects on the tensile strength of brazed Fe-Cr-Al alloy (Fecralloy (R)) with Ni-based filler metal and corresponding image processing based analysis

Abstract

Brazing bonding of iron-chromium-aluminum alloy (Fecralloy) with nickel based filler metal (MBF20) were performed at different maximum temperatures, 1000 degrees C and 1100 degrees C by varying the rate of temperature rise, 5 degrees C/min and 10 degrees C/min. And for comparison, diffusion bonding of Fecralloy-Fecralloy was also done with a condition, 1000 degrees C and 10 degrees C/min. For testing the tensile strength, the prepared tensile strength specimens were just bonded for diffusion bonding, and filler metal was inserted between the half specimens for brazing bonding. And in order to visually investigate about the bonding conditions, channeled heat plates were also prepared. The dimension of Fecralloy plates was 49 mm x 24 mm x 2 mm thick with three 2 mm diameter channels and 60 urn thick MBF20 was used as filler metal. The cross section parts of the test specimens were analyzed with SEM (XRD, EDS, EPMA, BSE) images, which were image processed to quantify the penetration depth of both filler and base metals to counter materials and components distribution using image processing. And such quantified results were compared with the tensile strength. From the both analysis, the tensile strength results were correlated with the change of thickness of filler metal as well as the distribution of components at the different bonding conditions.