354 Prakt. Met. Sonderband 38 (2006) 
All of these phenomena can be explained by the fact that the brazing temperature was too 
high. 
= The solubility for Fe and Cr in the Cu during brazing increases and during cooling 
more precipitates are formed. 
= Cu diffusion into the steel increases (liquid metal embrittlement). 
— The austenitic stainless steel recrystallises. 
The simplest explanation for the failure of the investigated heat exchanger is that the 
brazing temperature for stainless steel plates with pure Cu was too high. 
To avoid this problem the process parameters (temperature, purity of the atmosphere etc.) 
should be observed accurately. 
Alternatively to increase the corrosion resistance of the whole heat exchanger another 
braze can be used. E 
U 
0 
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