17-4 PH Stainless Steel
17-4 PH is a precipitation-hardening stainless steel that combines high strength with good corrosion resistance, and can be hardened by a single low-temperature ageing treatment after machining.
- Family /
- Stainless Steels
- Machinability /
- ~48%
- Condition /
- Condition A, or aged (H900 / H1075 / H1150)
- Also called /
- seventeen four
17-4 PH is a precipitation-hardening stainless steel that combines high strength with good corrosion resistance, and can be hardened by a single low-temperature ageing treatment after machining.
Machinability is approximate and rated against free-machining 1212 steel at 100%. Higher is easier to cut.
What it is
It is supplied in the solution-annealed condition (Condition A) and hardened by holding it at a relatively low temperature — H900, H1075 and H1150 refer to the ageing temperature in Fahrenheit. Lower ageing temperature gives higher strength; higher gives more toughness.
How it cuts
In Condition A it machines reasonably, roughly comparable to a tough alloy steel and better than 304. In the aged conditions it is considerably harder and needs rigid setups and appropriate tooling.
What catches people out
Because ageing happens at low temperature, distortion is small — which is exactly why the material is chosen for close-tolerance hardened parts. It is not zero, though, so critical features on tight-tolerance parts are still best finished after ageing.
17-4 PH Stainless Steel — Common Questions
What do H900 and H1150 mean on a 17-4 PH drawing?
- They are ageing treatments named for their temperature in Fahrenheit. H900 ages at 900°F and gives the highest strength and hardness; H1150 ages at 1150°F and gives lower strength with better toughness and ductility. The condition must be stated, because the same material behaves very differently in each.
Should 17-4 PH be machined before or after ageing?
- Usually rough and semi-finish in Condition A, then age, then finish critical features. Ageing happens at low temperature so movement is small, but on close-tolerance work it is not negligible.
Other stainless steels
Got a part for 17-4 PH Stainless Steel?
Send the drawing or the sample. We will tell you straight what it will take to make.