Stainless Steel Grade AISI 418 | EN 1.4313

AISI 418 | EN 1.4313 | DIN X3CrNiMo13-4 is a martensitic stainless steel designed for primary forming into forged products. The alloy has a relatively high base value among wrought martensitic stainless steels. In addition, it has a fairly high tensile strength and a moderately high embodied energy.

Soft martensitic chromium stainless steel with 4% nickel added is used in fittings, pumps, compressors, turbines, reactors and naval equipment. This martensitic chromium-nickel alloy with added molybdenum is rust-resistant in the quenched and tempered condition. It is used in the temperature range from -60 °C to +300 °C due to its good toughness properties.

The metal made of this steel is well polished. It has good corrosion resistance in a moderately aggressive environment in which there are no chlorides. The surface condition plays a huge role in corrosion resistance. The resistance of this material is much better with a polished surface than the same material with a rough surface.

Welding

AISI 418 | EN 1.4313 can be easily welded by all arc welding processes. Preheating the workpiece to 150 °C is recommended, especially when welding large sections (>10 mm). After welding, the material must be hardened to restore ductility in the weld zone. Any tint or heat resulting from welding or high-temperature treatment must be either mechanically or chemically removed, followed by a suitable passivation treatment to restore corrosion resistance.

Forging

When forging AISI 418, the material should be gradually heated to a temperature of about 850 °C before being rapidly heated to a temperature of 1100 °C to 1150 °C. Forging then takes place at a temperature between 1150 °C and 950 °C.

Processing

The machinability of this grade of stainless steel is directly related to its hardness. The machining process itself is very similar to the machining process of carbon steels of the same hardness. Although it is clear that the machining parameters will vary depending on the structure / hardness of the steel.

Physical properties

Table No. 1: physical properties of stainless steel grade AISI 418 | EN 1.4313 | DIN X3CrNiMo13-4
Density g/cm³	7,7
*Specific heat capacity at +20°C, J/kgK**	430
*Thermal conductivity at +20°C, W/mK**	25
*Specific electrical resistance at +20°C, μOhmm**	0,60
Magnetic properties	magnetic

Table No. 2: physical properties of stainless steel grade AISI 418 | EN 1.4313 | DIN X3CrNiMo13-4
Temperature	+20°С	+100°С	+200°C	+300°С	+400°С	+500°С
Modulus of elasticity, GPa	200	195	185	175	170	-
Coefficient of linear expansion, 10^-6/°C	10,5	10,5	10,9	11,3	11,6	-

Table: chemical composition of steel grade AISI 418 | EN 1.4313 | DIN X3CrNiMo13-4
Chemical composition of steel grade AISI 418 \| EN 1.4313 \| DIN X3CrNiMo13-4
C	Si	Mn	P	S	Cr	Mo	Ni	N	Fe
<0,05	<0,70	<1,5	<0,040	<0,015	12,0-14,0	0,30-0,70	3,5-4,5	≥0,020	Other

Super martensitic stainless steel

AISI 418 | EN 1.4313 | DIN X3CrNiMo13-4 is also known as a type of super martensitic stainless steel. “Super martensitic stainless steel” is a steel that is improved by martensitic melting process, has a lower carbon content and adds Ni and Mo chemical elements into its composition, and its performance is superior to ordinary martensitic stainless steel.

Performance

Super martensitic stainless steel has good corrosion resistance, weldability, high strength and good low temperature toughness.

Application

It has great potential in the fields of hydroelectric power station, mining equipment, chemical equipment, food industry, transportation and high-temperature pulp equipment. It is usually often used as hydroelectric power station steel and is a good material for hydraulic turbine equipment.