Heat treatment dissimilar materials

Heating an assembly in a furnace should be used when practical however, the size or shape of the unit or the adverse effect of a desired heat treatment on one or more components, where dissimilar materials are involved, may dictate alternative procedures. 

With this electrochemical technique galvanic currents between dissimilar electrode materials are measured with a zero resistance ammeter. The design of dissimilarities between sensor elements may be made to target a feature of interest in the system being monitored (e.g., different compositions, heat treatments, stress levels, or surface conditions). Zero resistance ammetry (ZRA) may also be applied to nominally identical electrodes in order to reveal changes occurring in the corrosivity of the environment. 

Heat treatment of welded joints between dissimilar ferritic metals or between ferritic metals using dissimilar ferritic filler metal should be at the higher of the temperature ranges in Table 11.13 for the materials in the joint. 

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