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Stainless Steel

17-4 PH Stainless

17-4 PH is a precipitation-hardening martensitic stainless that combines high strength (1070 MPa tensile, 1000 MPa yield, 38 HRC) with good corrosion resistance (4/5). A single low-temperature aging step develops its strength, so parts can be machined soft then hardened with minimal distortion, a rare and valuable combination.

How 17-4 PH Stainless machines

Rated 2/5 and genuinely tough. It's usually machined in the solution-annealed (Condition A) state, then aged. Even soft it's strong and gummy with low thermal conductivity, so use rigid setups, sharp coated carbide, positive rake, generous coolant, and conservative speeds. Machining after aging is possible but slower and harder on tools.

Manufacturing & processing

CNC machining is the primary process. The defining step is precipitation aging: heat treatments like H900, H1025, or H1150 trade strength for toughness at increasing temperatures. Machine in Condition A, then age, accepting only slight dimensional growth. Weldable (low carbon resists cracking) with post-weld aging recommended. Holds tight tolerances through hardening.

Typical applications

Aerospace fittings and structural hardware, pump and valve shafts, turbine and compressor components, firearm parts, marine fasteners, and medical/dental instruments. Chosen anywhere high strength must coexist with corrosion resistance and dimensional stability, such as down-hole oilfield tools and high-load valve stems.

When to choose it

Choose 17-4 PH when you need both high strength and corrosion resistance with predictable, low-distortion hardening after machining. If you only need machinability in a hardenable stainless, 416 is cheaper and easier. If maximum corrosion resistance matters more than strength, use 316.

Suitable surface finishes

Common finishes for 17-4 PH Stainless: passivation, electropolishing, bead blasting, brushed. Use the finish selector →

FAQ

What do the H900 and H1150 conditions mean?
They are aging treatments named for the Fahrenheit temperature. H900 (900°F) gives maximum strength near 1300 MPa but lower toughness; H1150 (1150°F) overages to lower strength with greater ductility and toughness. You pick the condition to balance strength against toughness for your loading.
Should I machine 17-4 before or after aging?
Machine in the solution-annealed Condition A, then age. Aging causes only minor, predictable dimensional growth, so tight tolerances survive the heat treatment. Machining the fully hardened material is possible but much slower and harder on tooling; reserve it for finishing critical features.
How corrosion-resistant is 17-4 PH compared to 316?
Good but not equal. At 4/5 it resists general atmospheric and mild chemical corrosion well, but it lacks 316's molybdenum, so it pits more readily in chlorides and saltwater. When you need both high strength and severe chloride resistance, consider duplex grades or coatings.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.