Nitriding steel | 2 Types of Nitriding steel.

NITRIDING STEEL.

Nitriding steel
nitriding steel

Nitriding steel are available in round bar, flat bar and steel plate. Nitriding is a heat treatment process that introduces nitrogen in to the surface of a steel and dependant on the material and nitriding process, a nitride case depth of 0.05mm up to 0.50mm can be achieved. With a high surface hardness nitriding steel grades offer increased wear resistance. This can improve fatigue life and also improve the corrosion resistance.

TYPES OF NITRIDING STEEL.

EN45B nitriding steel:

EN40B is a chromium molybdenum steel usually supplied in the hardened and tempered ‘T’ condition, which offers high wear resistance together with good toughness and ductility. EN40B in T condition has a tensile of 850-1000 N/mm². It is characterized by its suitability for nitriding, which can give a hard wear resistant case in the range of 61-65Rc. The relatively low temperature of the nitriding process produces EN40B components with a scale free surface, with minimum distortion during the heat treatment process. EN40B may be used in its supply condition (usually ‘T’) for applications and components which require a high tensile steel strength and high creep strength at temperatures up to 600°C.

Analysis
Carbon 0.20-0.30% Chromium 2.90-3.50%
Silicon 0.10-0.35% Nickel 0.40% max.
Manganese 0.40-0.65% Phosphorous 0.05% max
Molybdenum 0.40-0.70% Sulphur 0.05% max.
Applications EN40B is suited for applications that require excellent resistance to wear and abrasion combined with high fatigue strength. Typical applications include shafts, extruders, gear wheels, drills, guides, pins, spindles and bolts. Widely used in the automotive, textile and general engineering industries.

Forging Preheat carefully, then raise temperature to 850-1200°C for forging. Do not forge below 850°C. After forging EN40B alloy steel, cool slowly in still air.

Annealing Heat slowly to 680-700°C. Cool in air.

Hardening EN40BT is supplied ready heat treated. If further heat treatment is required annealed EN40B should be heated slowly to 880-910°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 570-700°C). Soak at the temperature for 2 hours per 25mm of ruling section, then allow to cool in the air
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 steel 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 EN40B alloy steel.

EN41 nitriding steel:

EN41 is a chromium aluminium molybdenum steel specification usually supplied in the hardened and tempered ‘R’ or ‘S’ condition. EN41 ‘R’ condition has a tensile of 700-850 N/mm². EN41’S’ condition has a tensile of 775-925 N/mm². It offers high wear resistant properties together with toughness and ductility. It is defined by its suitability for nitriding from which EN41 can give a hard wear resistant case up to 68HRc, better than achievable with the similar nitriding grade .

Chemical 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%
Applications EN41 is suited for applications that required excellent resistance to wear and abrasion. Typical applications include connecting rods, small extruders, valve stems, dies. It is widely used in the automotive, textile and general engineering industries. Suitable for applications requiring a resistance to wear, it is also suitable for other applications such as brick press plates, clutch plates, gudgeon, track and shackle pins.

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.
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.