Available Shapes
EN40B Nitriding Steel
EN40B (722M24) is a chromium-molybdenum based engineering steel grade from Thames Stockholders which is often delivered in the hardened and tempered condition. It benefits from good wear resistance and high fatigue strength. This can increase a tensile strength of up to 1075 N/mm². Nitriding yields a hard and wear resistant casing resulting in an engineering material which delivers good fatigue and shock resistance. The nitriding process is usually performed at a comparatively low temperature which brings about a scale-free surface with minimal distortion.
EN40B (722M24) can function in atmospheres of up to 500 °C before any loss in surface hardness is noticed. EN40B is delivered in the hardened and tempered ‘T’ condition. This nitriding steel also offers a good combination of toughness and ductility. When supplied in the ‘T’ condition, EN40B is ideal for applications necessitating high creep resistance and high tensile strength.
EN40B (722M24) has become a widely used engineering material in industries such as automotive, textiles, and aerospace. It is also widely used by billet crankshaft manufacturers.
Applications
Analysis
Annealing
Hardening
Tempering
Typical Mechanical Properties*
Heat Treatment
Applications
Typical applications include connecting rods, extruders, valve stems, dies, ring & plunger, Screw and barrel for injection moulding machines
Analysis
| Carbon | 0.35-0.45% | Manganese | 0.65% max |
| Silicon | 0.10-0.45% | Nickel | 0.40% max |
| Chromium | 1.40-1.80% | Phosphorous | 0.05% max |
| Molybdenum | 0.10-0.25% | Sulphur | 0.05% max |
| Aluminium | 0.90-1.30% |
Annealing
Heat slowly to 650-700°C. Cool in air.
Hardening
EN41 is supplied ready heat treated. If further heat treatment is required annealed EN41 should be heated slowly to 870-930°C and after adequate soaking at this temperature quench in oil/polymer or water. Temper as soon as tools reach room temperature.
Tempering
Heat carefully to a suitable temperature selected by reference to a tempering chart or table (usually between 580-700°C). Soak at the temperature for 2 hours per 25mm of ruling section, then allow to cool in the air.
Typical Mechanical Properties*
| Condition | Tensile N/mm² | Yield N/mm² | Elongation % | Izod KCV J | Hardness Brinell |
|---|---|---|---|---|---|
| R | 700-850 | 525 | 17 | 50 | 201-255 |
| S | 775-925 | 585 | 15 | 50 | 223-277 |
(*subject to ruling section)
Heat Treatment
Heat treatment temperatures, including rate of heating, cooling and soaking times will vary due to factors such as the shape and size of each component. Other considerations during the heat treatment process include the type of furnace, quenching medium and work piece transfer facilities. Please consult your heat treatment provider for full guidance on heat treatment of EN41 alloy nitriding steel.
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