17-4PH stainless steel is a magnetic precipitation hardening--martensitic stainless steel with special metallic elements copper and niobium.17-4PH stainless steel is the most widely used material of all the precipitation-hardening stainless steels. After heat treatment, the mechanical properties will be more perfect, and the tensile strength can reach the compressive strength of 1100-1300 Mpa (160-190 ksi). This grade cannot be used above 300C (572F) or very low temperature . 

Corrosion resistance

The corrosion resistance of the 17-4 PH alloy is superior to any other standard hardenable stainless steel. In most cases, its corrosion resistance is no less than 304. If there is a risk of stress corrosion cracking, the higher curing temperature must be above 550oC (1022oF), preferably 590oC (1094oF). The optimum tempering temperature in the chloride medium is 550oC-1022oF. The optimum tempering temperature in H2S media is 590oC-1094oF. This alloy is susceptible to corrosion or crack corrosion in static seawater. It has the same corrosion resistance as the 304L grade in the petrochemical, food processing and paper industries. 

Machining

We can machine the 17-4 PH alloy in a solution treated or quenched and hardened state. The processing conditions vary with the hardness of the material. We usually use high speed tools or lubricated carbonizing knives for machining. If the customer has very stringent tolerance requirements, we should also consider the dimensional changes that may occur during heat treatment.

Processing

Hot forming

Hot forming should be performed at a temperature range of 950-1200oC (1742-2192oF). Complete heat treatments include solid solution annealing, cooling (less than 25oC), and aging (at a given temperature). 

Cutting

Thermal cutting (plasma, saw, etc.): This grade of cutting procedure should be appropriate in consideration of the hot metamorphic part. After cutting, it is ground to remove the oxide layer. Mechanical cutting: shearing, stamping, cold sawing, etc.

Welding

17-4 PH alloys can be soldered as follows: SMAW, GTAW, PAW and GMAW. SAW welding can only be carried out after preliminary tests (check for cracks and toughness of weld metal). Due to the solidification of the ferrite, the possibility of hot cracking and thermal deterioration of the weld metal is reduced. In general, no preheating is required and the intermediate temperature is controlled at 120 .