17-4 PH is the precipitation-hardening stainless that lets you machine soft and then harden: cut it in Condition A (solution treated, around 30 HRC), then age to H900 (40 HRC, 1310 MPa tensile) or H1025 for a better toughness balance. That workflow is its main advantage — and its main trap, because the part moves during aging.
| Tensile strength | 1310 MPa (H900) |
|---|---|
| Yield strength | 1170 MPa (H900) |
| Hardness | 40 HRC (H900) |
| Density | 7.80 g/cm³ |
| Elongation | 10% (H900) |
| Thermal conductivity | 18.4 W/m·K |
| Series | Precipitation hardening |
Typical values for the standard condition (Stainless Steel 17-4 PH (Grade 630)). Heat treatment, temper and product form move these numbers — confirm against the mill certificate for your order.
Very high strength after aging (up to 1310 MPa) with stainless corrosion resistance
Machined in the soft condition, which keeps machining cost reasonable
Aging is a simple, low-distortion heat treatment compared with quenching
Well established in aerospace, medical and high-pressure applications
Starting parameters for carbide tooling. These are the shop's working numbers, not brochure values — adjust for machine rigidity, tool geometry and workholding.
| Surface speed | 60–100 m/min (Condition A) |
|---|---|
| Feed per tooth | 0.05–0.12 mm/tooth |
| Tooling | AlTiN coated carbide |
| Coolant | Flood |
Machine in Condition A, then age harden. Machining after hardening is possible with carbide but slow and hard on tooling. Plan for dimensional change during aging — leave stock on critical features and finish after heat treatment where tolerances are tight.
Material is expensive and the two-step process (machine, then age) adds handling and a heat-treat line item. The value is a part with 1310 MPa strength that still resists corrosion.
For the full cost structure — material, programming, setup, cycle time, finishing and inspection — see CNC machining cost per hour, and for how price changes with quantity see machining by production volume.
Before, in Condition A. Aging to H900 raises hardness to about 40 HRC, which makes machining slow and hard on tooling. The standard workflow is machine in Condition A, then age. The catch is that aging causes dimensional change, so tight-tolerance features need stock left on and a finishing operation after heat treatment.
Both are aging conditions. H900 (aged at 900°F) gives the highest strength, around 1310 MPa, with lower toughness. H1025 trades some strength (around 1070 MPa) for better toughness and ductility. Selection depends on whether the design is strength-limited or toughness-limited.
It is comparable to 304 in many environments, though not as resistant as 316L in chlorides. It performs well in atmospheric, fresh water and many chemical exposures. For salt water or high-chloride service, confirm the specific environment rather than assuming stainless equals immune.
Yes, and it is commonly welded in the Condition A state followed by a full heat treatment. Welding in the aged condition is possible but creates a heat-affected zone with different properties. If the part is welded, discuss the sequence before machining.
Tell us the grade and temper, the quantity and what the part has to do. You get a line-item quote within 24 hours, with DFM feedback on anything that is raising the cost.