T.O. 33B-1-1 4-8 Table 4-3.  Conductivity’s of Some Commonly Used Engineering Materials. Material Conductivity Megaohms/Inch** Conductivity (%IACS) Temperature (°F) Aluminum Base* 1060-0 2014-T6 2024-T3 2024-T851 5052-0 6061-T6 7075-T6 0.913 0.589 0.174 0.589 0.516 0.589 0.442 62.0 35.5 - 41.5 28.5 - 32.5 36.0 - 42.5 33.6 - 37.6 40.0 - 48.0 30.5 - 36.0 69 68 68 — 68 68 68 Copper Base 99.9%, Annealed Cartridge Brass,   Annealed Aluminum Bronze - 5%,   Annealed Phosphor Bronze - 5%,   Annealed 1.473 0.412 0.250 0.221 100.0 28.0 17.0 15.0 68 68 68 68 Magnesium Base Pure, Annealed K60A-0 AZ31B-T5 0.560 0.442 0.273 38.0 30.0 18.5 68 68 70 Nickel Base A, 99.4% Monel 400 Inconel 600 0.265 0.053 0.025 18.0 3.6 1.7 68 68 70 Stainless Steel 304 430 0.353 0.423 2.4 2.9 70 70 Titanium Base Ti-55A 6Al-4V 8A1-1Mo-1V 0.045 0.015 0.013 3.1 1.0 0.87 — — — 4.2.2.1.1.5   Effect of Conductivity on Eddy Currents. The   distribution   and   intensity   of   eddy   currents   in   non-ferromagnetic   materials   is   strongly   affected   by   electrical conductivity.  In a material of relatively high conductivity, strong eddy currents are generated at the surface.  In turn, the strong eddy currents form a strong secondary electromagnetic field opposing the applied primary field.  As a result the  strength  of  the  primary  field  decreases  rapidly  with  increasing  depth  below  the  surface.    In  poorly  conductive materials, the primary field generates small amounts of eddy currents, which produce a small opposing secondary field. Therefore, in highly conductive materials, strong eddy currents are formed near the surface, but their strength reduces rapidly  with  depth.    In  poorly  conductive  materials,  weaker  eddy  currents  are  generated  near  the  surface,  but  they penetrate to greater depths.  The relative magnitude and distribution of eddy currents in good and poor conductors are shown in Figure 4-4.