17-4 PH Heat Treatment Process
The heat treatment of 17-4 PH stainless steel pipe generally involves three main steps: solution treatment, quenching, and aging.
1.Solution Treatment:
Temperature: The s31700 material is heated to a temperature range of 1025-1050°C (1877-1922°F).
Purpose: This step dissolves the copper-rich phases, homogenizing the alloy and preparing it for precipitation hardening.
Duration: The 1.4542 AISI 630 material is held at this temperature for about 0.5 to 1 hour.
Cooling: Rapid cooling (quenching) in air or oil to room temperature to retain the solution-treated structure.
2. Aging (Precipitation Hardening):
Temperature: The aged temperature varies depending on the desired mechanical properties. Common aging temperatures are:
H900: 482°C (900°F)
H1025: 552°C (1025°F)
H1075: 580°C (1075°F)
H1150: 620°C (1150°F)
Purpose: The aging process precipitates fine particles (mainly copper) that strengthen the steel.
Duration: Typically held at the aging temperature for 1 to 4 hours, depending on the desired properties.
Cooling: Air cooling to room temperature.
Mechanical Properties by Condition
The aging temperature selected determines the final mechanical properties of the 17-4 PH stainless steel:
17 4PH H900 (482°C/900°F):
- Highest strength and hardness.
- Moderate toughness.
- Tensile Strength: Approximately 190 ksi (1310 MPa)
- Yield Strength: Approximately 170 ksi (1170 MPa)
- Hardness: Approximately Rockwell C 44
17 4PH H1025 (552°C/1025°F):
- Balanced strength and toughness.
- Suitable for general applications.
- Tensile Strength: Approximately 155 ksi (1070 MPa)
- Yield Strength: Approximately 145 ksi (1000 MPa)
- Hardness: Approximately Rockwell C 38
17 4PH H1075 (580°C/1075°F):
- Increased toughness.
- Slightly reduced strength compared to H900.
- Tensile Strength: Approximately 145 ksi (1000 MPa)
- Yield Strength: Approximately 135 ksi (930 MPa)
- Hardness: Approximately Rockwell C 32
17 4PH H1150 (620°C/1150°F):
- Maximum toughness and ductility.
- Lower strength compared to other conditions.
- Tensile Strength: Approximately 135 ksi (930 MPa)
- Yield Strength: Approximately 105 ksi (725 MPa)
- Hardness: Approximately Rockwell C 28
