PRODUCT INFORMATION: 17-4PH (630) STAINLESS STEEL PLATE

1. Material Designation

• Common Names: 17-4PH, 630 Stainless Steel

• UNS: S17400

• EN / Euronorm: 1.4542

• AMS: 5604 (Bar), 5643 (Forgings), 5345 (Investment Castings)

• ASTM: A564 (Age-Hardened SS), A693 (Precipitation Hardening SS)

• Other: X5CrNiCuNb16-4

2. Material Type

• Class: Precipitation-Hardening (PH) Stainless Steel

• Structure: Martensitic (after heat treatment)

3. Key Characteristics

• High Strength: Achieves very high strength and hardness through precipitation hardening heat treatment (aging).

• Good Corrosion Resistance: Superior to standard martensitic stainless steels (e.g., 410, 420); comparable to Type 304 in many environments. Resists mild acids, salt spray, and fresh water.

• Good Toughness & Ductility: Maintains reasonable toughness and ductility at high strength levels.

• Excellent Fabricability: Can be readily machined and formed in the solution annealed (Condition A) state. Welding requires care and post-weld heat treatment (PWHT).

• Dimensional Stability: Minimal distortion during heat treatment compared to quench-hardened steels.

• Magnetic: Magnetic in all conditions.

4. Chemical Composition (Typical Weight % - ASTM A564)

5. Mechanical Properties (Typical - Plate)

Properties vary significantly based on heat treatment condition (see section 7).

6. Physical Properties

• Density: 7.78 g/cm³ (0.282 lb/in³)

• Melting Range: ~1400-1440 °C (2550-2625 °F)

• Electrical Resistivity: 81 µΩ·cm (at 20°C)

• Thermal Conductivity: 18.4 W/m·K (at 100°C)

• Coefficient of Thermal Expansion: 10.8 µm/m·°C (20-100°C)

7. Heat Treatment

• Solution Annealing (Condition A): 1038°C ±14°C (1900°F ±25°F), hold for sufficient time, air cool or rapid cool. Required before aging.

• Precipitation Hardening (Aging): Heat to specific temperature, hold for 4 hours (minimum), air cool. Common aging temperatures:

  • H900: 482°C (900°F) - Highest Strength/Hardness

  • H925: 496°C (925°F)

  • H1025: 552°C (1025°F)

  • H1075: 579°C (1075°F)

  • H1100: 593°C (1100°F)

  • H1150: 621°C (1150°F) - Higher Toughness/Ductility

  • H1150M: 621°C (1150°F) - Modified hold time for improved toughness.

8. Fabrication

• Machining: Best performed in the Solution Annealed (A) condition. Becomes significantly harder and more difficult after aging. Use rigid setups and positive rake tools.

• Forming: Good formability in Condition A. Requires greater force than austenitics. Anneal if severe cold work is done before aging.

• Welding: Weldable using common methods (TIG, MIG, SMAW). Use matching or austenitic filler metals (e.g., ER630, ER308L, ER309L). Crucial: Must be solution annealed after welding and before final aging to restore corrosion resistance and achieve full properties. Preheat usually not required. Control interpass temp.

• Grinding/Finishing: Responds well to standard grinding and polishing techniques.

9. Corrosion Resistance

• Resists corrosion in:

  • Mild atmospheric environments

  • Freshwater

  • Seawater (with care regarding crevices/stagnation)

  • Mild acids and alkalis

  • Food processing environments

  • Moderately oxidizing environments.

• Not suitable for highly reducing acids (e.g., sulfuric, hydrochloric) or severe marine/salt exposures without protection. Resistance generally better than 410/420, similar to 304 in many applications. Susceptible to stress corrosion cracking (SCC) at higher strength levels (e.g., H900) in chloride environments; H1150/H1150M offer better SCC resistance.

10. Typical Applications

• Aerospace components (fittings, fasteners, engine parts, landing gear)

• Oil & Gas Industry (valve parts, pump shafts, wellhead components, downhole tools)

• Chemical Processing Equipment (shafts, gears, valves)

• Power Generation (turbine blades, fasteners)

• Food Processing Equipment (cutting blades, mixing shafts)

• Medical Instruments & Surgical Tools

• High-Strength Structural Components

• Nuclear Waste Containers

11. Available Forms & Sizes (Plate)

• Thickness: Typically ranges from 0.5mm (0.020") up to 150mm (6") or more (subject to mill capability).

• Width: Commonly 1000mm, 1219mm, 1500mm, 2000mm (39", 48", 60", 78") or custom.

• Length: Typically 2000mm, 2438mm, 3000mm, 6000mm (78", 96", 118", 236") or custom.

• Surface Finish: Hot Rolled (HR), Hot Rolled Annealed & Pickled (HRAP), Cold Rolled (CR), Cold Rolled Annealed & Pickled (CRAP), ground, polished

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