N685 Stainless Steel

N685 is a stainless martensitic chromium steel with a high carbon content, addition of molybdenum and vanadium. N685 steel is an excellent choice for those looking for a strong, durable and sharp knife. Its characteristics make it popular among both professionals and amateurs.

Characteristics

Viscosity and plasticity: good;
Wear resistance: very high;
Machinability: good;
Dimensional accuracy: good;
Suitability for polishing: good;
Corrosion resistance: high.

Chemical composition

Table: chemical composition of steel grade N685
Chemical composition of steel grade N685
C	Cr	Mo	V	Mn	Si	Fe
0,9	17,5	1,1	0,1	0,4	0,45	Other

Application

Hot runner systems;
Molds;
Food industry such as extrusion screws, can sealing rollers, etc.;

Pharmaceutical industry such as punches and dies for tablet presses;
Extrusion screws for plastic processing;
Other.

Heat treatment

Typically N685 stainless steel is supplied in annealed condition with a maximum hardness of 265 HB.

Table: heat treatment of steel grade N685
Heat treatment of steel N685
Stress relieving
Temperature	max. 650 °C	Soft annealed material: for stress relief annealing after mechanical processing, hold the material at temperature in a neutral atmosphere for 1-2 hours after complete heating, then slowly cool the furnace at 20 °C [68 °F]/hour to 200 °C [392 °F], then cool in air.
Temperature		Hardened and tempered material: the temperature for stress relief annealing should be approx. 50 °C [122 °F] below the previously selected tempering temperature. Other procedure as for stress relief annealing of soft annealed material.
Hardening and Tempering
Temperature	1,000 to 1,050 °C	For hardening, hold the material at the specified temperature for 15-30 minutes after complete heating and quench quickly. Cool the material to approx. 30 °C [86 °F]. Tempering should take place immediately.
Temperature	100 to 200 °C	Tempering treatment to the desired working hardness after hardening - see tempering diagram. Heat the material slowly and temper once for 1 hour/20mm material thickness, but at least 2 hours. After the heat treatment step, the material must be cooled to approx. 30 °C [86 °F].

Tempering chart

Tempering chart of steel N685

Hardening temperature: 1030 °C / 1886 °F;
Specimen size: square 20 mm;
Hardness up to 57 - 59 HRC.

Physical properties

Table: physical properties of steel grade N685
Temperature °C	20
Density (kg/dm³)	7.7
Thermal conductivity (W/(m.K))	15
Specific heat (kJ/kg K)	0.43
Spec. electrical resistance (Ohm.mm²/m)	0.8
Modulus of elasticity (10³N/mm²)	215

Thermal Expansions between 20°C | 68°F and ...

Table: thermal expansion of steel grade N685
Temperature °C	100	200	300	400	500
Thermal expansion (10⁻⁶ m/(m.K))	10.4	10.8	11.2	11.6	11.9

N685 is a high-quality stainless steel that is often used to produce knives and other tools that require high strength and corrosion resistance. This alloy has a number of characteristics that make it a popular choice among manufacturers.