Square bar shaft helical piles Bar material: 40cr or 45# steel, round corner 5mm radius Helix plate material conforms to astm a36 hot rolled plate Helices thickness are available in 3/8â?� and 1/2â?� inch All helix leading edges sharpened and rock cut and 45 degrees. Corrosion protection to conform to astm a153 standard for hot dipped zinc coating A better conventional solid steel extra high strength helical screw pile Welded coupling for greater strength. Eliminates shaft heat damage caused by upset coupling process