Vacuum Heat Treatment Process for 17-4PH Stainless Steel

I. Material Characteristics of 17-4PH H900

17-4PH (UNS S17400; Chinese National Standard: 05Cr17Ni4Cu4Nb; commonly known as “630”) is a martensitic precipitation-hardening stainless steel.

H900 refers to a specific aging condition of this alloy, characterized by high strength and high hardness.

II. Primary Applications (H900 is predominantly used in high-strength scenarios)

• Aerospace: Landing gear components, high-strength engine bolts, airframe connectors, satellite structural components.
• Precision Molds: High-load plastic injection molds, die-casting molds, mold cores, mold inserts.
• Energy: Pump shafts, valves, fan shafts, high-strength fasteners.
• Medical: Orthopedic implants, high-end surgical instruments.
• General Machinery: High-strength shafts, gears, cams, high-pressure valves, offshore platform components.

III. Vacuum Heat Treatment Process

1) Solution Treatment

• Purpose: To dissolve precipitated phases, obtain a soft martensitic structure, and facilitate subsequent machining.
• Temperature: 1040–1050°C
• Holding Time: 1 hour per 25 mm of effective thickness.
• Vacuum Level: 1–10 Pa
• Cooling: Vacuum oil quenching (or rapid cooling with high-purity nitrogen); remove from furnace only when temperature drops to ≤100°C.
• Hardness: HRC 28–34

2) Vacuum Aging (H900 Condition)

• Purpose: To precipitate copper (Cu) nanoscale phases, thereby significantly increasing strength and hardness while inducing minimal dimensional distortion. Temperature: 480 ±5℃
• Holding Time: 250–270 min (4 h ±10 min)
• Vacuum Level: 1–10 Pa
• Heating Rate: ≤10℃/min
• Cooling: Vacuum / Protective atmosphere air cooling to room temperature
• Final Hardness: HRC 40–45

3) Practical Vacuum Furnace Process Profile

• Room Temp → 850℃ (Preheating), hold for 30–40 min
• 850℃ → 1045℃, hold
• Vacuum oil quench to below 80℃
• Cleaning → Aging (in furnace):
• Room Temp → 480℃, hold for 4 h → Air cool (out of furnace)

4) Key Considerations

The H900 condition exhibits relatively low toughness and sensitivity to stress corrosion cracking; for applications involving high stress combined with corrosive environments, the H1150 condition (620℃ × 4h) is the preferred choice.

The aging temperature is best controlled at approximately 490℃.

Vacuum heat treatment prevents oxidation, decarburization, and surface discoloration, allowing for dimensional precision reaching the 0.005 mm level.

IV. Selection of Heat Treatment Equipment

The VQGQ series vacuum oil quenching furnaces manufactured by SIMUWU are high-quality products designed for the vacuum heat treatment of materials such as carbon steel, tool steel, mold steel, high-speed steel, and ultra-high-strength steel. Their excellent temperature control precision and uniformity ensure the effective execution of the vacuum quenching process. The heating elements in SIMUWU vacuum oil quenching furnaces are constructed from high-purity graphite; this material possesses superior quality, exhibits excellent high-temperature resistance and electrical conductivity, and offers greater energy efficiency compared to standard graphite. Key electrical components within SIMUWU vacuum oil quenching furnaces are sourced from internationally renowned brands, ensuring high quality while facilitating convenient future maintenance, replacement, and rapid component matching.

SIMUWU focuses on the manufacturing of vacuum furnaces and has more than ten years of relevant experience, enjoying a good reputation in the field of vacuum furnace manufacturing. The product line includes vacuum gas quenching furnaces, vacuum oil quenching furnaces, and vacuum brazing furnaces, which are widely sold to developed and developing countries.

If you would like to learn more about vacuum furnace equipment, please send your requirements to kevin.liu@vacfurnace.com, and our company will provide you with a satisfactory solution.