178 inch 18Ni Maraging Alloy 350 Steel Round bars are made of a carbon free ironnickel blend of steel with hint of aluminum, titanium, cobalt, and Molybdenum This composition of metals results in a very high strength, low weight metal often used in the aerospace industryThe 350 alloy is heavier and harder than its 300 and 350 counterpart alloys due to higher amounts of Cobalt and Titanium.