CARBON 1040 STEEL STRUCTURAL PLATE- Used when greater strength and hardness is desired in the as rolled condition. Good for hammer forge processes. Uses include gears, shafts, axles, bolts sand studs. 1040 is a medium-carbon steel composed of 0.37 to 0.44 percent carbon, 0.6 to 0.9 percent manganese, a maximum of 0.04 percent phosphorus and a maximum of 0.05 sulphur. The remainder is iron. 1040 steel sometimes contains 0.1 to 0.35 percent silicon, according to Interlloy, an Australia-based alloy engineering steel, tool steel and specialty steel producer.

CARBON 1040 STEEL STRUCTURAL PLATE equivalent to EN8/080M40. An unalloyed medium carbon steel. AISI 1040 is a medium strength steel with good tensile strength. Suitable for shafts, stressed pins, studs, keys etc. 1040 must be pre-heated to 300 to 500 degrees F before welding and reheated to between 1100 degrees F and 1200 degrees F after welding. Otherwise, the area near the weld may develop cracks or become brittle and cause the part to fail during use.

Tensile Strength
Ultimate tensile strength is the maximum load a material will support before it breaks, explains Instron, a materials testing laboratory. Ultimate tensile strength testing is a destruction test. The purpose is to find the point at which a material will fail when supporting a given load or sustaining a set force.

CARBON 1040 STEEL STRUCTURAL PLATE will support 90,000 pounds of force per square inch before it fails, if it was hot-rolled. This strength drops to 85,500 psi when the steel has been normalized, or returned as closely as possible to the state it was in when it was produced. Tensile strength drops even further, to 72,250, when it has been annealed, or brought to its softest point while cold.

Normalizing and annealing are two examples of heat treatments. In heat treatment the temperature of the steel is changed in order to alter its molecular structure and change its reaction to various forces during forging and fabrication, according to metallurgist David Pye's heat treatment tutorial at Moldmaking Technology.