Machinability of this alloy is good in the annealed condition. In the heat treated and quenched condition machining is best limited to finish grinding. The 4140 that we offer for sale here on our website is in the Cold Drawn Annealed condition. We can also provide this product in a Normalized or Heat Treated state. Please contact us toll free @ 888-752-7272 if you need help with this. As with all the low alloy steels forming may be done by conventional methods with the alloy in the annealed condition. These alloys have good ductility, but are tougher than plain carbon steel and thus usually require more force, or pressure, for forming. 4140 Alloy Steel is weldable by all of the conventional methods. Note that welding with the alloy in the heat treated condition will affect the mechanical properties and a post weld heat treatment may be needed. Typical applications include Arbors, Axle Shafts, Bolts, Crankshafts, Connection Rods, Chuck Bodies, Collets, Ejector Pins, Forks, Gears, Guide Rods, Hydraulic Shafts & Parts, Lathe Spindles, Milling Spindles, Motor Shafts, Pinions, Pump Shafts, Spindles, Sprockets, Studs, Tool Holders and Torsion Bars.