Neutrons, as a probe for studying defective functioning of temperature controller membranes

Neutron radiography and diffraction measurements were performed on temperature controller membranes in order to detect the origin of their defective functioning. The inner working processes were visualized in the thin channels of the sensor tubes by dynamic neutron radiography and the crystal structure characteristics of the stainless steel membrane were analysed by neutron diffraction. The coexistence of ferrite ( f ) and austenite ( n ) was identified in the membrane material. Structural changes caused by the applied technological processes were observed. As an effect of pressing, crystallization from the face-centred-cubic (FCC) n -phase to the body-centred-cubic (BCC) f -phase was observed that may lead to the formation of internal stresses, dislocations causing fragility of the membranes.