5/16-18X3/4 Unslotted Indented Hex Washer Thread Cutting Screw Type F Fully Thread 18-8 Stainless (Pack Qty 750) BC-3112FW188

Steel thread-cutters are used in heavy gauge sheet metal, aluminum, zinc and lead die castings, cast iron, brass and plastic. Stainless screws offer additional resistance to corrosion, 18-8 moreso than 410. When using any thread-cutting screw, the material in which the threads are cut should have a lower hardness by at least 10 to 20 Rockwell hardness points Steel: Screws shall be quenched in liquid and then tempered by reheating to 650°F minimum. 410 Stainless: Screws shall be annealed by heating to 1850-1950°F, held at least for 1/2 hour and rapid air- or oil-quenched then reheating to 525°F minimum for at Steel: AISI 1016 - 1024 or equivalent steel. Stainless: 410 martensitic stainless steel or 18-8 stainless steel