AISI 4317H Alloy Steel

Introduce:

4317 is a 1.8% chromium – nickel – molybdenum high hardenability, case hardening (carburizing) steel, generally supplied in the annealed condition with a maximum brinell hardness of 229 (Rc22). Characterised by high core strength and toughness in medium to large sections with case hardness up to Rc62 when carburized, hardened and tempered. 4317 can also be used (uncarburised) as a high tensile steel, which when suitably hardened and tempered can be utilized for various applications requiring good tensile strength and toughness. Pre hardened and tempered (uncarburized) 4317 can be further surface hardened by nitriding but will not respond satisfactorily to flame or induction hardening due to its low carbon content. 4317 (carburized) is used extensively by all industry sectors for components and shafts requiring high surface wear resistance, high core strength and impact properties.

Application:

Typical uses are: Heavy Duty Bushings and Bearings, Cam Followers, Clutch Dogs, Compressor Bolts, Extractors, Fan Shafts, Heavy Duty Gears, Pump Shafts, Sprockets, Tappets, Wear Pins, Wire Guides etc.

Supplying Size:

Rolled: Diameter 50-200mm

Forged: Diameter 80-600mm

*accepted special shape

Grade Compare:

Chemical Composition:

Mechanical Properties:

Forging:

Heat to 1150℃ and hold until temperature is uniform throughout the section. Soaking time at forging temperature should be as short as possible to avoid heavy scaling and excessive grain growth. This will vary depending on furnace conditions but 15 minutes per 25 mm of section may be used as a guide. Do not forge below 850 ℃. Following completion of forging operation, work piece should be cooled as slowly as possible in sand or dry lime etc. Note: Case hardening steels due to their low carbon content are less susceptable to cracking than medium or high carbon steels, and may therefore be heated and cooled more rapidly.

Heat Treatment:

1 Annealing: Heat to 830℃ – 850℃, hold until temperature is uniform throughout the section and cool in furnace.

2 Caburizing: Pack, salt or gas carburize at 900℃ – 930℃, holding for sufficient time to develop the required case depth and carbon content, followed by a suitable hardening and tempering cycle to optimise case and core properties.

3 Nitriding: Not suitable for nitriding.

4 Normalizing: Heat to 860℃ – 900℃, hold until temperature is uniform throughout the section. Soak for 10 – 15 minutes and cool in still air.

Refining & Hardening:

1 Core Refine: Slow cool from carburizing temperature and re-heat to 840℃ – 870℃, hold until temperature is uniform throughout the section, quench as required in warm water, oil or air cool. Alternatively quench in salt bath held at 150℃ – 250℃ followed by air cool.

2 Case Refining:Following core refining, re-heat to 780℃ – 820℃, hold until temperature is uniform throughout the section, and quench in oil.

Temper immediately while still hand warm.

3 Single Refine: Direct Quench: Cool from carburizing temperature to 820 ℃- 840 ℃, hold until temperature is uniform throughout the section. Quench in oil.Temper immediately while still hand warm. Or: Cool from carburizing temperature to room temperature, re-heat to 820 ℃ – 840 ℃ and hold until temperature is uniform throughout the section and quench in oil.

Temper immediately.

4 Stress Relieving: Heat to 630℃ – 650℃, hold until temperature is uniform throughout the section, soak for 1 hour per 25 mm section, and cool in still air.

5 Tempering: Heat to 150℃ – 200℃ as required, hold until temperature is uniform throughout the section, soak for 1 – 2 hours per 25 mm of section, and cool in still air. N.B. Tempering will improve the toughness of both case and core, with only a slight reduction in core strength and case hardness. It will also reduce the susceptibility of the case to grinding cracks.

Other Property:

Machining: 4317 in the annealed as supplied condition has very good machinability and all operations such as turning, drilling,milling and tapping etc. can be carried out satisfactorily as per machine manufacturers recommendations for suitable tool type – feeds and speeds.

Welding: 4317 is readily weldable in the annealed as supplied condition. Following welding, the work piece immediately upon cooling to hand warm should be stress relieved at 630℃ – 650℃ if possible. N.B. Welding in the carburized and heat treated condition is not recommended.

Welding: Welding of 4317 should always be carried out using low hydrogen electrodes – please consult your welding consumables supplier.