655M13 – 3.25% Ni – Cr Case Hardening Steel

655M13 is a 3.25% Nickel – Chromium high hardenability case hardening steel, characterised by high core strength, excellent toughness and fatigue resistance, with case hardnesses up to 62HRC when carburised, hardened and tempered.
Material is usually supplied in the Annealed condition upto 255HB
Material can be used in the un-carburised condition as a high tensile steel, which, when suitably hardened & tempered can be used for various applications requiring good tensile strength and toughness.
General applications include all industry sectors for applications requiring high surface wear resistance, high core strength & impact properties. Typical uses include Gears, King Pins, Sprockets and Shafts.

RELATED SPECIFICATIONS 655M13 – 3.25% Ni – Cr Case Hardening Steel
BS970-1955 EN36B
UNS G93106
W.Nr. 1.5752
DIN 14NiCr4
TYPICAL CHEMICAL COMPOSITION
Carbon 0.15%
Silicon 0.25%
Manganese 0.50%
Phosphorous <0.040%
Sulphur <0.040%
Chromium 0.90%
Nickel 3.50%
MECHANICAL PROPERTY REQUIREMENTS – Annealed condition
Yield Tensile Strength Elongation Hardness
540 Mpa 770/770 Mpa 25% 255 HB Max
MECHANICAL PROPERTY REQUIREMENTS – On Blank Carburised Test Piece – As required by BS970 Part 3 1991
Test Bar Diameter Tensile Strength Elongation Charpy Impact J Izod Impact Ftlbs Hardness HB
19mm 1000 9 40 35 255 Max
TYPICAL CORE PROPERTIES – Carburised and Oil Hardened at 830C
Section Size Yield Strength Mpa Tensile Strength Mpa Elongation % Charpy Impact J Hardness HB
11mm 1030/1320 835 9 55 300-385
30mm 930/1230 785 10 55 275-360
63mm 880/1180 735 10 - 260-350
NOTE: This material can be used in the hardened and tempered (Un-carburised) condition for heavy duty shock resisting shafts and parts requiring tensile strengths in excess of 1000Mpa in sections upto 200mm
FORGING
Forging temperature for this material should be 850 – 1150oC.
Soaking times should be kept to a minimum to avoid heavy scale and excessive grain growth, suggest 15minutes per inch (25mm) of ruling section.
HEAT TREATMENT
Annealing – Heat to 830 – 850oC ensuring sufficient time is allowed for the centre to achieve furnace temperature and hold for a time commensurate with the ruling section, followed by a slow furnace cool.
Carburizing – Pack, salt or gas carburizing at 900 – 950oC, hold for time commensurate with required case depth, followed by suitable hardening and tempering to optimise core properties.
Hardening – Heat to 830 – 880oC and hold for time commensurate with ruling section, quench as required in Water, Oil or Air. Salt bath quench held at 150 – 200oC followed by Air cooling could be used as an alternative
Note: This treatment is used for core refinement and should be followed by Tempering
Case Hardening – Following core refining above, re-heat to 760 – 800oC, hold for time commensurate with ruling section and quench in oil.
Note: Material should be tempered immediately whilst still hand warm.
Tempering – Heat to 150 – 200oC for sufficient time to allow centre to achieve furnace temperature, and hold for 2hrs minimum, cool in still air.
MACHINING
Material in the annealed condition is readily machinable by milling, drilling, turning, tapping etc as required.
WELDING
In the annealed condition the material is readily weldable using low hydrogen electrodes, however following cooling the material should be stress relieved at 600-650oC
Note: Welding in the carburized or Heat Treated condition is not recommended.