Stainless Steel Grade AISI 414 | EN 1.4008 | DIN GX7CrNiMo12-1

AISI 414 | EN 1.4008 | DIN GX7CrNiMo12-1 is a martensitic stainless steel designed for primary forming of wrought products. It has moderately high tensile strength among wrought martensitic stainless steels. This alloy is actually an improved version of AISI 410. The addition of nickel to its composition resulted in a steel that is stronger than AISI 403 and AISI 410 at similar strength levels.

This grade of stainless steel is commonly used in mining equipment in the form of forged shafts and spindles, valve seats, fasteners, rods, etc.

Forging

The material should be heated for forging to 1150 ºC - 1205 ºC and then forged. Small forgings should be cooled slowly. Large forgings are cooled in dry lime or ash. Parts should be cooled to room temperature before annealing after forging. Do not forge below 900 ºC.

Welding

The base metal should be preheated to 205 ºC - 315 ºC and maintained at 205 ºC during welding. Post weld treatment at 650 ºC should be carried out on the weld as soon as possible after cooling to room temperature.

Machinability

AISI 414 shows fairly good machinability, but some burrs will form on the cutting edge of tools.

Heat treatment

Annealing

For optimum workability, heat to 650 ºC - 675 ºC, soak and air cool.

Hardening

Heat to 980 ºC - 1065 ºC - soak and oil cool or air cool. If tempering is less than 370 ºC, use the high side of the austenitizing temperature for best impact toughness and similarly the low side of the austenitizing temperature when tempering above 540 ºC for best impact toughness.

Tempering

Temper at a temperature to give the desired mechanical properties. Soak for at least one hour - longer for larger parts - and air cool. Tempering between 370 ºC - 565 ºC may reduce toughness and corrosion resistance, but depending on other properties required, some impact and corrosion resistance may still need to be retained.

Mechanical properties

Physical properties