4140 Steel Heat Treatment Hardness

Aisi 4140 alloy steel can be hardened by cold working or heating and quenching.

4140 steel heat treatment hardness.

Alloy description timkensteel s 4140hw grade is a fine grained low alloy steel that offers optimum heat treat response in heavier cross sections. 3 tempering recommendations from the asm heat treaters guide for 4140 4142 is a minimum of 400 f. Tempering temperature of 4140 alloy steel can be from 204 649 c 400 1200 f after normalizing and oil quenching and the corresponding rockwell hardness can be obtained. 1 4140 is an ok die steel but is not recommended for radical shaped dies such as narrow fullering crown and so on.

Heat treatment to 845 c slow cooling from 755 c at a rate of 14 c 25 f hour to 665 c or rapid cooling to 675 c for 5 hours isothermal annealing. You find 4140hw in a. For example a tensile strength of 225 ksi can be achieved by tempering at 316 c 600 f and tensile strength of 130 ksi can be achieved by tempering at 538 c 1000 f. 4140 has a nominal carbon content of 4 and this carbon content will yield a hardness of rc 51 for a 90 martensitic structure 9th edition of the asm material handbook volume i.

For 4140 steel the recommended heat treatment 1 consists of heating to austenitizing temperature typically 1570 f 855 c followed by oil quenching. The hardness of the steel can be increased if it has a lower tempering temperature. But it should be tempered for any heavy use. Tempering reheating after quenching will achieve the desired hardness range.

This leaves near full hardness. Aisi 4140 alloy steel can be tempered at 205 to 649 c 400 to 1200 f depending upon the desired hardness level.