440c / S44004 / 1.4125
Technical Data

Heat Treatment

Technical data:
Hot forming temperature °C 1100 – 900

Annealing temperature °C 780 – 840

Hardening temperature °C 1000 – 1050
Quenchant Oil

Tempering temperature °C 100 – 300
Structure after Heat treatment Condition Product Size mm Hardness (average values) HB/HV
Ferrite + Carbide ≤ max. 285
Martensite + Carbide ca. 61 HRC
Martensite + Carbide hardened & tempered
for obtaining high hardness		 57 – 60 HRC
Physical properties at ambient temperature (average values):
Modulus of elasticity
103 N/mm2, at...°C 		Density kg/dm3
 Electric resistivity
Ohm.mm2/m 		Thermal conductivity
W/(m.K)
20°C 100°C 200°C 300°C 400°C      
215 212 205 200 190 7,70 0,80 15
Physical properties:
Specific heat
capacity
at 20°C 		Mean coefficient of thermal expansion between 20°C and ...°C, 10 (m/(m.K)
 Magnetic properties
  100°C 200°C 300°C 400°C 500°C  
430 J/(kg.K) 10,4 10,8 11,2 11,6 11,9 Magnetic
Chemical Composition
Chemical composition (%)    
C Si Mn P S Cr Mo
0,95-1,20 ≤ 1,00 ≤ 1,00 ≤ 0,040 ≤ 0,030 16,00-18,00 ≤ 0,75

Download - BÖHLER N695 - EXTRA Technical Data sheet in pdf format

Additional Technical Information for 1.4125 / 440c:

Mechanical Properties above ambient temperature:
Condition: Hardened & Tempered
Coeffecient of Thermal Expansion between 20ºC and...
Temperature ºC Coefficient (10-6 K-1)
100 10.5
200 11.0
300 11.0
400 11.5
500 12.0
Physical properties at 20°C
Density Specific Heat Heat Conduction Electrical Resistance Modulus of Elasticity Magnetic Polishable Weldable
  J
––––––
g.K 		W
––––––
K.m 		'Ω.mm2
––––––
m 		103N/mm2      
7.70 0.46 29.0 0.65 230 Yes Yes No

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440c Martensitic Stainless Steel

Characteristics

This material will achieve the highest hardness of the available hardenable stainless steels. It possesses good corrosion resistance, particularly in the hardened and tempered condition. The material is magnetic in all conditions.

Heat Treatment Practice

In order to achieve the optimum properties for this material, it is imperative that the correct heat treatment is carried out in accordance with the following recommendations:

Normalising

Normalising is not recommended

Annealing

Annealing may be required on material in the as forged condition in order to aid machining prior to hardening and tempering. Annealing should be carried out under vacuum conditions to avoid surface decarburisation.

Hardening

Hardening should be carried out under vacuum conditions to avoid surface decarburisation and to maintain a clean bright product.

Preheat 760ºC - 800ºC

Austenitise 1010ºC - 1065ºC

Nitrogen gas quench 2 - 6 bar overpressure

As quenched hardness 60/62 HRc

The upper end of the temperature range should be used for larger sections or when maximum corrosion resistance and strength are required. Similarly the greater quench pressure should be used in order to maximise these properties.

Sub Zero treatment

For minimum retained austinite and maximum dimensional stability, parts should be sub-zero treated between -70º / -80ºC.

This should be carried out immediately after hardening once the parts have reached ambient temperature.

Tempering

Tempering should be carried out depending on properties required, in all cases double tempering is recommended.

165ºC for maximum hardness 60 HRc

190ºC - 230ºC for a combination of hardness & toughness 56/58 HRc

350ºC for maximum toughness 52/54 HRc

Nitriding

To further enhance surface characteristics, post heat treatment nitriding may be carried out on this material. Typical depth achieved being 0.008/0.010"

Please note the above specification has been provided by and is the responsibility of the TTI Group Limited. This information is provided to further the possibilities to our customers. You must satisfy yourselves that this specification meets the criteria for your products.

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