ASTM A564/A564M — Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes
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Scope
Precipitation-hardening stainless bars and shapes: 17-4 PH (S17400, Type 630), 15-5 PH (S15500), 13-8 Mo (S13800), Custom 450/455, 17-7 PH (S17700), XM-12 etc. Defines Condition A and the aged conditions (H900–H1150, H1150M/D; RH950, TH1050) with minimum yield, tensile, elongation, reduction of area and hardness for each. Plate/sheet are in A693, forgings in A705.
Grades covered by ASTM A564
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Nearest equivalents |
|---|---|---|---|---|---|---|
| 17-4 PH | S17400 | Martensitic precipitation-hardening stainless steel | ≤ 0.07 | ≈ 760 (typ.) | ≈ 1030 (typ.) | 1.4542, SUS630, 05Cr17Ni4Cu4Nb |
Revision history and superseded standards
| Year | Change |
|---|---|
| 1965 | First issued |
| 2019 | A564/A564M-19 — current |
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Related standards
Age-hardening stainless is a different species
A564 covers hot-rolled and cold-finished age-hardening stainless bars and shapes — the precipitation-hardening family, of which 17-4 PH (UNS S17400) is the best known. These steels reach 1 000 MPa and beyond while remaining stainless, which austenitic grades cannot do without heavy cold work.
The mechanism is precipitation of copper or aluminium-bearing phases during a low-temperature ageing treatment, not the carbon martensite of an ordinary hardenable steel. That is why the treatment runs at 480–620 °C rather than above 800 °C, and why distortion is small enough that parts can be machined close to final size before ageing.
The condition code is the specification
A 17-4 PH bar is meaningless without its condition. Condition A is solution annealed — the as-supplied, machinable state. H900, H1025, H1075, H1150 name the ageing temperature in degrees Fahrenheit, and each produces a different strength and toughness combination: H900 is hardest and least tough, H1150 the reverse.
A drawing that calls for 17-4 PH without a condition has not specified a material property. The condition also has to be reachable from where the bar is: ageing is a one-way treatment, and re-solution annealing before a different ageing cycle is a separate operation with its own dimensional consequences.