SS · stainless
Stainless Steel 15-5 PH
The same family as 17-4 PH with better toughness and fewer large-section problems. Annealed it machines like a tough stainless; aged it needs CBN or ceramic to finish.
Quoting this material
- Typical lead time
- 12–18 working days
- Condition
- Condition A (annealed) or aged H925 / H1025 / H1075 / H1150
- Achievable finish
- Ra 1.6 µm annealed typical · Ra 0.4 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
The same family as 17-4 PH with better toughness and fewer large-section problems. Annealed it machines like a tough stainless; aged it needs CBN or ceramic to finish.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength (H1025) | 1,170 | MPa |
| Yield strength (H1025) | 1,070 | MPa |
| Elongation (H1025) | 12 | % |
| Hardness (H1025) | 40 | HRC |
| Thermal conductivity | 17.9 | W/m·K |
| Modulus of elasticity | 196 | GPa |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Condition A (annealed) or aged H925 / H1025 / H1075 / H1150
Heat treatment
Precipitation hardening like 17-4, but with lower delta-ferrite, which matters on heavy sections where 17-4 can show property variation through the thickness. Age between roughly 480 °C and 620 °C depending on the strength/toughness balance required.
Achievable surface finish
Ra 1.6 µm annealed
Ra 0.4 µm
Finished after ageing; passivated afterwards for corrosion-critical work.
Tooling and cutting parameters
Cutting speed
- 120–200 m/min annealed (carbide) · 60–90 m/min aged
Feed
- 0.10–0.25 mm/rev turning · 0.06–0.15 mm/tooth milling
Tooling
- Coated carbide annealed, CBN for the aged condition
Coolant
- Flood
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Aerospace structural components
- High-pressure valve bodies
- Pump and compressor shafts
- Nuclear and power generation hardware
- Defence mechanical components
DFM notes for this grade
- On a section thicker than about 75 mm, 15-5 is the safer choice over 17-4 - the ferrite content in 17-4 makes the properties vary through heavy sections
- Rough before ageing, finish after: the same rule as 17-4, and for the same reason
- Toughness is the difference it sells: H1025 gives 40 HRC with noticeably better impact behaviour than 17-4 at the same hardness
Questions buyers ask
- 15-5 or 17-4 - how do I choose?
- Look at the section thickness and the loading. Thin sections and ordinary structural loads: 17-4 is cheaper and more widely available. Heavy sections, impact loading or a fatigue-critical part: 15-5 is more consistent through the thickness and tougher at the same strength.
- Can 15-5 PH be welded?
- Better than 17-4, generally yes in the annealed condition followed by a full age, which is what the specification will call out. It is not a “weld and forget” grade like 304L.
Grades we would quote instead
17-4 PH
4/10In the annealed condition it machines like a tough 304; in H900 it is hard enough that finishing has to be done by grinding or hard turning.
316L
3/10Harder to machine than 304 and it galls more, but it is the grade for chlorides, medical and marine.
420
4/10Martensitic and hardenable to about 50 HRC, which is the point of it.