Stainless Steel Grade AISI 442 | EN 1.4742 | DIN X10CrAlSi18

AISI 442 | EN 1.4742 | DIN X10CrAlSi18 is a heat-resistant ferritic chromium stainless steel with the addition of aluminum. It is characterized by resistance to sulfur-containing gases. Due to the higher chromium content, it is more resistant to high-temperature oxidation than EN 1.4724, but less resistant than EN 1.4762, which contains even more chromium.

EN 1.4742 has a high resistance to oxidation by sulphur gases and has a somewhat lower but still good resistance to sulphur-containing gases in reducing atmospheres. It is moderately resistant to carburising gases, but not resistant to high temperatures or oxygen-carbonated gases. This grade of stainless steel is resistant to scaling in air at temperatures up to 1000 °C.

Welding

Weldable using all conventional welding processes with preheating to temperatures between 200 °C and 300 °C. Low heat inputs should be used during welding to reduce possible grain coarsening. Although post weld heat treatment is not required, stress relieving in the temperature range of 650 °C to 800 °C is sometimes recommended when there are large cross-sectional differences or when components are subject to severe cold work.

If an austenitic filler is used and the component is intended for use in a sulfur containing or carburizing environment, the austenitic weld must be transitioned with a ferritic weld to provide some resistance to the working environment.

Forging

Forging is usually done at 1150 °C - 800 °C, followed by rapid cooling in air or water. Forging is usually followed by heat treatment.

Mechanical processing

AISI 442 | EN 1.4742 tends to smear during machining, resulting in longer chips. This makes machining more difficult. When machining this steel grade with metal cutting / machining tools, use appropriate machining parameters.

Mechanical properties

Physical properties

It has a relatively low electrical conductivity among deformed ferritic stainless steels. In addition, it has a relatively low ductility and moderately high tensile strength.

Cold forming

When cold forming EN 1.4742, certain preventive measures must be taken. Sheets up to 3 mm thick can be cold-bent if preheated to 200 °C - 300 °C. Products with a thickness of ˃3 mm must be preheated to 600 °C - 800 °C. In general, the workability of this grade of material is comparable to low-carbon steel.

Embrittlement

When AISI 442 | EN 1.4742 | DIN X10CrAlSi18 is heated to approximately 950 °C, embrittlement occurs due to grain growth, which can no longer be eliminated. Further embrittlement occurs in the temperature range from 400 °C to 550 °C (embrittlement at 475 °C). Longer periods in this temperature range should be avoided. This loss of ductility can be corrected by short-term heating to 700 °C - 800 °C. In the temperature range from 600 °C to 900 °C, the alloy is prone to sigma-phase embrittlement, so that after long-term use in this temperature range, the ductility values ​​​​are greatly reduced. The steel should not be put into service in this temperature range if mechanical stresses exist.