Stainless Steel Grade AISI 420 | EN 1.4021 | DIN X20Cr13

AISI 420 | EN 1.4021 | DIN X20Cr13 is used in the hardened and tempered condition in many structural and fastening products where moderate corrosion resistance is required. Optimum corrosion resistance is also achieved with fine grinding or polishing of the surface.

It has good corrosion resistance in moderately aggressive environments that do not contain chlorides, such as soap, detergents and organic acids. Good resistance to atmospheric oxidation at temperatures up to 600 °C. Not resistant to intercrystalline corrosion during welding.

Welding

Preheating of the material to a temperature in the range of 100 °C to 300 °C is required. The use of an appropriate filler material is also necessary during welding. To restore ductility in the weld zone, it is recommended to work at 650 °C after welding. When using inert or shielding gas during welding, care must be taken to avoid the use of any gases containing hydrogen or nitrogen, since contamination of the weld with nitrogen or hydrogen will adversely affect the mechanical properties. After welding, the material must be cooled to a martensitic start at a temperature of approximately 120 °C before quenching.

Heat treatment

EN 1.4021 steel can be soft annealed by holding at a temperature in the range from 745 °C to 825 °C followed by slow cooling in air. It can be hardened by holding at a temperature from 950 °C to 1050 °C followed by cooling in air or oil. The tempering temperature depends on the desired strength. Due to the precipitation of undesirable phases, the temperature range from 400 °C to 600 °C should be avoided.

Forging

Before more rapid heating to a temperature of 1150 to 1180 °C, gradual heating to a temperature of about 850 °C is recommended first. Then the forging process takes place at a temperature of 1100 - 900 °C, followed by slow cooling in a furnace or dry ash or similar material.

Processing

The machinability of this grade of stainless steel is directly related to its hardness. The machining process resembles that of carbon steels of approximately the same hardness. The machining parameters may vary depending on the structure / hardness of the steel.

Physical properties

Mechanical properties

Application

This grade is used for the production of bolts at elevated temperatures, turbine blades, knives, decorations, surgical instruments, bushings, valve seats, scrapers, blades, shafts, springs, machine parts, injection molds and pins subject to light loads. Also in the automotive, petrochemical, hydraulics and power industries.