17-4PH is a well-established precipitation hardening martensitic stainless steel capable of obtaining very high strength and hardness after a relatively simple heat treatment . It offers excellent corrosion resistance along with a set of mechanical property levels structured depending on the precise heat treatment applied.
The advantage of precipitation hardening steels is that they can be supplied in an easily machinable "solution treated" condition. After machining or another fabrication method, a single low temperature heat treatment can be applied to increase the strength of the steel. This is known as aging or aging. Since it is carried out at low temperature, the component does not suffer any deterioration.
Materials can be easily machined and fabricated in softer temper and then heat treated to exceptional strength and dimensional stability. 17-4PH is widely used in the chemical, petrochemical, offshore, paper and aerospace industries, making the most of its exceptional corrosion resistance, wear resistance, strength and hardness.
17- 4, PH stainless steel maintains a high precipitation hardening strength stainless steels Most applications are in the aerospace industry . It is also used in the construction of engine components, aircraft structures, gears and shafts.
Precipitation hardened stainless steels have moderate to good corrosion resistance in a variety of environments. They have a better combination of strength and corrosion resistance compared to heat- treatable 400 series martensitic alloys. Corrosion resistance is similar to those found in 304 grade stainless steel.
In hot chloride environments, 17-4 PH is susceptible to pitting and crevice corrosion. When aged at 550 ° C or higher, it is highly resistant to 17-4 PH stress corrosion cracking. Better stress corrosion cracking resistance comes with higher aging temperatures.
In the solution applied (annealed) state it has low corrosion resistance and should not be used before heat treatment.
17-4 PH has good oxidation resistance. It should not be used above the precipitation hardening temperature to prevent a reduction in mechanical properties. If the harshness of the ambient temperature is critical, prolonged exposure to 370-480 ° C should be avoided.
17-4 PH stainless steel hot work should be done at 950 ° -1200 ° C. Full heat treatment is required after hot working. This includes annealing and cooling to room temperature or below. The component must then be cured by precipitation to achieve the required mechanical properties.
In the annealed condition, 17-4 PH has good machinability similar to 304 stainless steel . After hardening heat treatment, machining side is difficult but possible.
Carbide or high speed steel tools are normally used with standard lubrication. Dimensional changes due to heat treatment should be considered when precise tolerance limits are required.
Precipitation hardening steels can be easily welded using procedures similar to those used for 300 series stainless steels.
17-4 PH grade stainless steel materials can be welded successfully without preheating. Post-weld heat treatment can be used to give the weld metal the same properties as the base metal.