17-4PH / UNS S17400 Precipitation-Hardening Stainless Steel Plate (Grade 630)

Core Identity & Advantage

• Engineered for Performance: A martensitic precipitation-hardening (PH) stainless steel specifically designed to deliver exceptional strength-to-weight ratios and maintainable mechanical properties after fabrication.

• Key Value Proposition: Achieves high strength & hardness (exceeding many austenitic grades) while retaining superior corrosion resistance compared to conventional martensitic steels, all through controlled heat treatment.

Material Specifications & Standards

• Common Names: 17-4PH, Stainless 630, SUS 630 (JIS)

• Primary Standards:

  • UNS: S17400

  • EN (Euronorm): 1.4542 (X5CrNiCuNb16-4)

  • Key Product Standards: ASTM A693 (PH Forgings), ASTM A564 (PH Bar/Shapes), AMS 5604/5643, ISO 4954

  • Plate Specific: Often supplied to ASTM A240 (General Requirements) or customer-specific dimensional specs.

Defining Characteristics

1. Tailorable Strength: Mechanical properties are primarily defined by the final aging heat treatment. Choose from a spectrum:

   • Peak Strength (H900): ~1310 MPa UTS, ~40-45 HRC - For maximum load-bearing.

   • Balanced Performance (H1025/H1075): ~1000-1200 MPa UTS - Optimal blend of strength, toughness, and corrosion resistance.

   • Enhanced Toughness/Ductility (H1150/H1150M): ~795-860 MPa UTS, ~24-30 HRC - For improved impact resistance and stress corrosion cracking (SCC) resistance.

2. Robust Corrosion Performance: Offers resistance significantly better than 410/420 series, often comparable to Type 304 in:

   • Atmospheric exposure

   • Fresh & mildly brackish water

   • Dilute acids/alkalis

   • Food, petrochemical, and general industrial environments.

   • Note: SCC susceptibility increases with strength level; H1150/M is preferred for chloride-rich environments.

3. Fabrication Flexibility: Excellent machinability and good formability in the Solution Annealed (Condition A - ~1035 MPa UTS, ~32 HRC) state. Final properties are developed after forming/machining via aging.

4. Magnetic: Exhibits magnetic properties in all conditions.

Critical Processing: Heat Treatment

• Mandatory First Step: Solution Annealing (Condition A)

  • Process: Heat to 1025-1050°C (1875-1920°F), hold, cool rapidly (air or faster).

  • Purpose: Dissolves precipitates, creates a soft, uniform martensitic structure ready for aging.

• Property-Defining Step: Precipitation Hardening (Aging)

  • Process: Heat to specific temperature (482-621°C / 900-1150°F), hold 1-4 hours, air cool.

  • Condition Selection Guide:

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

    • H1025: 552°C (1025°F) - High Strength

    • H1075: 579°C (1075°F) - Intermediate Strength

    • H1100: 593°C (1100°F) - Moderate Strength/Ductility

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

    • H1150M: 621°C (1150°F) w/ modified time - Optimized Toughness for thick sections/SCC resistance.

Fabrication Considerations - Key Points

• Machining: Perform before final aging. Condition A offers good machinability (~80% of B1112 steel). Use sharp tools, positive rake angles, adequate coolant, and avoid work hardening. Hardness increases dramatically after aging.

• Forming: Best done in Condition A. Requires more force than austenitics. Anneal if severe cold work (>~15%) is performed prior to aging.

• Welding:

  • Recommended Processes: GTAW (TIG), GMAW (MIG), SMAW (Stick) with low heat input.

  • Filler Metals: Matching (e.g., ER630, E630) or austenitic (e.g., ER308L, ER309L) for crack resistance.

  • Crucial Post-Weld Protocol:

    1. Solution Anneal the entire welded assembly.

    2. Perform the final aging heat treatment.

  • Preheating (100-150°C / 212-300°F) and strict interpass temperature control (<150°C / 300°F) are recommended.

Why Choose 17-4PH Plate? Target Applications

• Aerospace: Structural brackets, engine mounts, landing gear components, fasteners (high strength/weight).

• Oil & Gas: Valve stems & bodies, pump shafts, wellhead equipment, downhole tools (corrosion + strength).

• Chemical Processing: Shafts, impellers, gears, valve trim (resistance to process fluids).

• Power Generation: Turbine blades (LP stages), fasteners, compressor parts.

• Industrial Machinery: High-stress shafts, gears, couplings, hydraulic components (wear resistance).

• Medical & Dental: Surgical instruments, implantable device components (biocompatibility + strength).

• Defense: Firearm components, missile parts.

• Additive Manufacturing (AM): Widely used metal powder for high-strength AM parts.

Supply Details (Plate)

• Thickness Range: 0.5mm (0.020") to 150mm (6")+ (Availability subject to mill).

• Widths: Standard mill widths (e.g., 1000mm, 1500mm, 2000mm / 39", 60", 78"), custom widths possible.

• Lengths: Standard (2000mm, 3000mm, 6000mm / 78", 118", 236"), custom lengths available.

• Surface Finishes: Hot Rolled Annealed & Pickled (HRAP), Cold Rolled Annealed & Pickled (CRAP), Ground, Polished (e.g., #4, BA, Mirror).

Quality & Compliance

• Mandatory Certification: Supplied with Mill Test Certificate (MTC) conforming to EN 10204 3.1 or 3.2, verifying chemistry, mechanical properties (per condition), and traceability.

• Dimensional Tolerance: Compliant with ASTM A480 or customer drawing.

• Non-Destructive Testing (NDT): Ultrasonic Testing (UT) available per ASTM A578 or customer spec for critical applications.

• Traceability: Full heat/lot traceability maintained.

Critical Ordering Information

• Specify Condition: Essential! Clearly state required heat treatment (e.g., "Solution Annealed (Condition A)", "Aged to H1025", "Solution Annealed for subsequent aging by customer").

• Specify Dimensions: Thickness, Width, Length, Tolerances.

• Specify Surface Finish.

• Specify Certification & Testing Requirements (e.g., EN 10204 3.2, UT Level).