1.4542 Stainless Steel Overview

17-4PH (1.4542) is a well-known precipitation hardened martensitic stainless steel that is able to achieve very high strength and hardness levels after simple heat treatment. It offers excellent corrosion resistance and a range of mechanical properties that vary depending on the precise heat treatment conditions.

Corrosion Resistance:

Precipitation hardened stainless steels have moderate to good corrosion resistance in a wide range of environments. They combine better strength and corrosion resistance than the 400 series martensitic alloys. Their corrosion resistance is similar to that of 304 grade stainless steel.

In hot chloride environments, 1.4542 is susceptible to pitting and crevice corrosion. It is highly resistant to stress corrosion cracking when aged at 550°C or higher. Higher aging temperatures result in better stress corrosion cracking resistance.

In the annealed condition, it has low corrosion resistance and is therefore not recommended before heat treatment.

Heat resistance:

1.4542 has good oxidation resistance. To prevent degradation of mechanical properties, it should not be used above the precipitation hardening temperature. If the ambient temperature is extremely severe, prolonged exposure to 370-480°C should be avoided.

Hot working:

Hot working of 1.4542 stainless steel should be performed between 950°C and 1200°C. A complete heat treatment is required after hot working, including annealing and cooling to room temperature or lower. A precipitation treatment must then be performed to achieve the desired mechanical properties.

Machinability

In the annealed condition, the machinability of 1.4542 is similar to that of 304 stainless steel. Machining becomes more difficult after the hardening heat treatment, but is still possible.

Carbide or high-speed steel tools are usually used, and standard lubrication is used. When exact tolerance limits are required, dimensional changes caused by heat treatment should be considered.

Weldability

Precipitation hardened stainless steels can be welded easily and the welding process is similar to that of 300 series stainless steels. 1.4542 material can be welded successfully without preheating. Post-weld heat treatment can be used to give the weld metal the same properties as the base material.

Applications

1.4542 stainless steel is mainly used in the aviation industry and in the manufacture of high-strength, corrosion-resistant parts.

Chemical composition:

The typical chemical composition of 1.4542 stainless steel is as follows:

• Carbon (C): max. 0.07%

• Chromium (Cr): max. 17.5%

• Copper (Cu): max. 4.0%

• Phosphorus (P): max. 0.035%

• Manganese (Mn): max. 1.0%

• Sulphur (S): max. 0.025%

• Niobium (Nb): max. 0.45%

• Nickel (Ni): max. 4.0%

Mechanical properties:

The mechanical properties of 1.4542 stainless steel are as follows:

• Density: 7.9 g/cm³

• Specific heat capacity: 500 J/kg K

• Thermal conductivity: 15 W/m K

• Modulus of elasticity: 0.73 Ω mm²/m

• Hardness HB 30: max. HB 215

• 0.2% yield strength R ≥: 175 MPa

• Tensile strength Rm: 460-680 MPa

• Elongation A ≥: 45% (annealed) / 35% (solution)

• Elastic modulus: 200 kN/mm²