The effect of prior austenite grain size and carbide particle morphology (diameter and density) on Barkhausen noise (BHN) signals was studied as one of the basic research for non-destructive estimation of the quenching temperature in 0.4C–5Cr–Mo–V hot-work tool steel. Signals of BHN were detected on surfaces of plate specimens by a contact type sensor and analyzed by a digital spectrum analyser to determine the intensity of generated BHN signals. It became clear that total power voltage (Vp) of BHN signals depended strongly on mean values of diameter (dp) and density (N) of carbide particles.