Grade 4140 alloy steel rods contain chromium to improve corrosion and wear resistance, and molybdenum to resist high temperatures and cracking. Grade 4140 is also known as chrome-moly and Chromoly steel. These rods have good torsional strength and are easy to weld. They are often manufactured into automotive and aerospace components, shafts, gears, axles, and other parts under continual stress.

Grade 4340 alloy steel rods resist fatigue and wear, and maintain their shape at elevated temperatures. They are easy to weld, machine, and are often manufactured into crankshafts, gear shafts, and other automotive and aircraft parts and components. Additional applications include hydraulic parts and machine tools.