HEAT-TREATMENT SELECTION
Select the 17-4 PH condition from required properties—not temperature alone.
H900 gives the highest common strength direction; higher aging conditions generally trade strength for toughness and stress-corrosion resistance.
Starting condition
Confirm Condition A and the governing product specification before choosing an aging schedule.
Final acceptance
Order by minimum mechanical properties, impact requirements, hardness, dimensions and inspection—not only “H900” or “H1150.”
Engineering caution: Do not apply a workshop heat-treatment recipe without confirming section size, furnace control, product form and specification.
Quick selection: 17-4 PH stainless steel (Type 630, UNS S17400) is normally solution treated to Condition A and then aged to the condition required by the purchase specification. H900 provides the highest common strength; progressively higher aging temperatures generally trade strength for greater toughness and stress-corrosion resistance. Do not choose an aging condition from temperature alone—product form, section size, governing standard, impact requirement, corrosion environment and dimensional change all matter.
| Condition | Common aging schedule from Condition A | Typical selection direction |
|---|---|---|
| H900 | 900°F (482°C), 1 hour, air cool | Highest common strength/hardness; lower toughness and SCC margin |
| H1025 | 1025°F (552°C), 4 hours, air cool | Strength-toughness balance |
| H1075 | 1075°F (580°C), 4 hours, air cool | More toughness, lower strength than H900/H1025 |
| H1150 | 1150°F (621°C), 4 hours, air cool | Greater toughness and stress-corrosion resistance; lower strength |
| H1150M | Two-step treatment defined by the applicable material procedure | Overaged condition for particular toughness/SCC or processing objectives |
Important: these are common reference schedules reported for wrought 17-4 PH material. The purchase standard, mill data and approved heat-treatment procedure control actual furnace tolerance, soak time, loading, section-size adjustment and cooling. Powder, cast, welded or additively manufactured parts may require different procedures.
Solution treatment dissolves the strengthening constituents and prepares the alloy for precipitation hardening. After cooling below the transformation range, the structure becomes predominantly martensitic. Condition A is machinable and can be supplied under relevant standards, but many service applications require subsequent aging.
A generic instruction to heat every part to 1900°F for “30 minutes minimum” is incomplete. Qualified solution treatment depends on product form, section size, furnace uniformity, load arrangement and cooling method. Carpenter’s wrought-material guidance, for example, distinguishes rapid air cooling and suitable liquid quenching by section size. Follow the applicable material specification and mill procedure rather than applying a single workshop recipe.
Copper-rich precipitation during aging increases strength and hardness. Aging at the lower end of the range produces a high-strength condition; higher-temperature aging produces an overaged structure with reduced strength but improved ductility, toughness and resistance to stress-corrosion cracking in many environments.
| Requirement | Condition-selection question |
|---|---|
| Maximum room-temperature strength | Does H900 meet impact, corrosion and cracking requirements? |
| Impact toughness | Which higher aging condition and test temperature are specified? |
| Stress-corrosion resistance | Does the service specification require H1025, H1150 or another qualified condition? |
| Dimensional stability | Has aging contraction and machining allowance been included? |
| Elevated-temperature service | Are code allowables and time-at-temperature data available for the selected condition? |
ASTM A564/A564M covers age-hardening stainless steel bars and shapes and permits Type 630 in solution-treated or age-hardened conditions. Other product forms use different standards. A plate, forging, wire, fastener or aerospace bar should not be accepted using a heat-treatment table copied from another product form.
When purchasing 17-4 PH stainless steel bar or related sheet and plate, specify the governing standard, final condition and required tests. If the buyer will perform aging after machining, confirm whether the supplied Condition A material and certificate are suitable for that route.
Define whether the order requires tensile testing, yield strength, elongation, reduction of area, hardness, impact testing, corrosion or stress-corrosion qualification, ultrasonic examination, PMI and dimensional inspection. The Mill Test Certificate should identify the heat/lot, grade, standard, supplied condition and reported test results.
Hardness can support process control but should not be used as the only proof of complete heat treatment when the purchase specification requires tensile or impact properties.
H900 normally provides the highest common strength and hardness, but it is not automatically the best condition because toughness and stress-corrosion requirements may control.
Some standards permit supply in Condition A, but end-use suitability must be assessed. Material guidance warns that the solution-treated condition may have lower stress-corrosion resistance than appropriately aged conditions.
Higher aging temperatures generally improve stress-corrosion resistance compared with peak-aged H900, but general corrosion, pitting and service performance still depend on environment, surface condition and design.
Hardness is useful but may overlap between conditions or miss local nonuniformity. Use the tests and traceability required by the governing specification.
Request 17-4 PH in a defined condition
Send the product form, standard, Condition A/H900/H1025/H1075/H1150 requirement, dimensions, quantity, tests, certificate and destination to sales@sakysteel.com.
Technical RFQ
Turn the article into a usable purchase specification.
Send the product form, dimensions, required condition and standard to sales@sakysteel.com.