Abstract: The characteristics of copper wires are widely used in fire accident investigations. This article adopts two working conditions, GSL-1100X tube furnace radiation heating and n-hexane open flame heating, to heat the copper wire to a temperature of 100~1 000 ℃, and reduce it to room temperature through furnace cooling, natural cooling, and water cooling. Using MATLAB software, based on foreground assisted K-means algorithm to cluster and identify the L*a*b* color of wires in photos, quantitatively analyzed the relationship between the surface color of copper wires and heating and cooling conditions. The results show that the surface color of copper wires changes from dark gold to black, then to red, and finally to dark gray with increasing temperature; The overall color change of the open flame heating condition lags behind that of the radiation heating condition; In the open flame heating condition, the color of water cooling tends to be bluer and has a smaller change compared to natural cooling. Based on the above analysis, a fire scene accident investigation approach based on the surface color of copper wires is proposed, providing reference for rapid fire investigation.

Key words: fire physical evidence, radiation heating, flame heating, copper wire, discoloration