ENGINEERING STEELS + ALLOYS
EN39B Case Hardening Steel |
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| EN39B is a 4 1/4% Nickel Chromium Molybdenum carburising steel, generally supplied annealed to HB 277 max. Carburised and heat treated it develops a hard wear resistant case of about Rc 6-63 and a tough strong core with a typical tensile strength range 1000-1400MPa, in small to quite large sections. |
| Colour Code | Stocked Sizes | ||
| Green & Orange (Bar End)
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Rounds | 50mm to 205 mm Diameter | |
| Related Specifications | |
| Australia | AS X9315 / EN39B |
| Germany | DIN: 15NiCrMo16-5 |
| Great Britain | 835M15 or 835H15 |
| Japan | SNCM 815, JIS G 4103 |
| USA | EN: 39B |
| Chemical Composition | ||
| Min. % | Max. % | |
| Carbon | 0.12 | 0.18 |
| Silicon | 0.10 | 0.35 |
| Manganese | 0.25 | 0.50 |
| Nickel | 3.90 | 4.30 |
| Chromium | 1.00 | 1.40 |
| Molybdenum | 0.15 | 0.3 |
| Mechanical Test Requirements - If supplied to BS 970 - 1 - 1996 835M15 | |||||||||||||||||||||||||||||
Check test certificate if critical for end use. |
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| Typical Mechanical Properties - Quenched at 830oC and tempered at 200°C | |||||||||||||||||||||||||||||
| Section Size mm | 25 | 50 | 100 | ||||||||||||||||||||||||||
| Tensile Strength | 1350 | 1300 | 1180 | ||||||||||||||||||||||||||
| Yield Strength Mpa | 1150 | 1100 | 920 | ||||||||||||||||||||||||||
| Elongation % | 13 | 15 | 17 | ||||||||||||||||||||||||||
| Impact Izod J | 50 | 72 | 82 | ||||||||||||||||||||||||||
| Hardness HB | 400 | 380 | 350 | ||||||||||||||||||||||||||
| Forging | ||||
| Heat to 1150°C and hold until uniform. Minimum forging temperature 900°C. Cool in ashes, warm dry lime or sand.Note: Soaking time at forging temperature should be as short as possible to avoid heavy scaling and excessive grain growth. | ||||
| Heat Treatment | ||||
| Annealing | ||||
| Heat to 830oC - 850oC, hold until temperature is uniform throughout the section and cool in furnace. | ||||
| Normalising | ||||
| Heat to 900°C - 930°C, Cool in still air
Temper at 640°C - 660°C Cool in still air For optimum machinability |
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| Stress Relieving | ||||
| Heat to 600°C - 650°CCool in furnace to 450°C and air cool | ||||
| Carburizing |
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| Pack, salt or gas carburize at 900oC - 950oC, 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. | ||||
| Refining & Hardening | ||||
| Core Refine | ||||
| Slow cool from carburizing temperature and re-heat to 850oC - 880oC, hold until temperature is uniform throughout the section, quench as required in water, oil or air cool. Alternatively quench in salt bath held at 150oC - 250oC, followed by air cool. | ||||
| Case Hardening | ||||
| Following core refining, re-heat to 760oC - 800oC, hold until temperature is uniform throughout the section, and quench in oil.Temper immediately while still hand warm. | ||||
| Single Refine* | ||||
| Direct Quench: Cool from carburizing temperature to 810 oC - 830 oC, hold until temperature is uniform throughout the section. Quench as required in water, oil or air cool. Alternatively quench in salt bath held at 150 oC - 250 oC, followed by air cool and temper immediately.
Or: Cool from carburizing temperature to room temperature, re-heat to 810 oC - 830 oC and hold until temperature is uniform throughout the section and quench or air cool as previous. Temper immediately.
Note: When air cooling large sections a uniform fan cooling is recommended, especially when direct cooling from carburizing temperature.
*Suitable for fine grained steels only.
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| Tempering | ||||
| Heat to 150oC - 200oC 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. | ||||
| Welding | ||||
| EN39B is readily weldable in the annealed condition with correct procedure, but welding in the case hardened or through condition is not recommended. | ||||
| Welding Procedure | ||||
| Low hydrogen electrodes recommended. Pre-heat at 250°C - 350°C and maintain during welding. Cool slowly in ashes, warm dry lime or sand etc, followed when possible with a stress relieve. |
