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Eternal
The 17-4PH H1150 stainless steel forged shaft produced by Jiangyin Eternal Heavy Industry Co., Ltd. is a high-strength precipitation-hardening stainless steel forged shaft specially designed for heavy marine engineering equipment. It is used in critical connection and load-bearing positions on the 1,000-ton stinger of a Global Offshore pipe-laying vessel. The material is a 17-4PH (UNS S17400 / AISI 630) forging that has undergone H1150 aging heat treatment, achieving an optimal engineering balance among strength, toughness, and stress corrosion cracking resistance.
17-4PH is a martensitic precipitation-hardening stainless steel. The main alloying elements are chromium (Cr 15.00–17.50%) and nickel (Ni 3.00–5.00%), with copper (Cu 3.00–5.00%) and niobium + tantalum (Nb + Ta 0.15–0.45%) added as precipitation strengthening elements. Its chemical composition strictly follows the ASTM A564 / AMS 5643 standard:
Element | C | Si | Mn | P | S | Cr | Ni | Cu | Nb+Ta |
wt% | ≤0.07 | ≤1.00 | ≤1.00 | ≤0.040 | ≤0.030 | 15.00–17.50 | 3.00–5.00 | 3.00–5.00 | 0.15–0.45 |
Standard | Grade |
UNS / ASTM / AMS | S17400 / A564 Gr.630 / AMS 5643 |
GB | 05Cr17Ni4Cu4Nb（S51740） |
EN / DIN | X5CrNiCuNb16-4 / 1.4542 |
JIS | SUS630 |
AFNOR | Z6CNU17-04 |
KS | STS630 |
ISO | X5CrNiCuNb16-4 |
Gost | 07Х16Н4Д4Б 或 ХН4МДБТ |
The forged parts produced by Jiangyin Eternal Heavy Industry Co., Ltd. comply with the standards ASTM A564/A564M (hot-rolled and cold-worked precipitation-hardened stainless steel bars and forgings) and AMS 5643 (aviation-grade bars, forgings and rings). For marine engineering applications, the forged parts can be certified in accordance with the specifications of ship classification societies such as DNV, ABS, and BV, and provide a 3.1 or 3.2 certificate.
The quality of 17-4PH forgings is highly dependent on precise control of the forging process parameters. Jiangyin Eternal Heavy Industry Co., Ltd. uses electroslag remelted (ESR) or vacuum arc remelted (VAR) steel ingots as raw materials to reduce gas content, minimize inclusions, and improve transverse mechanical properties.
Key forging parameters:
Forging temperature range: initial forging temperature 1180–1200°C; final forging temperature not lower than 1010°C
Soaking schedule: a thickness of 25 mm corresponds to a soaking time of approximately 1 hour, with a minimum of no less than 15 minutes
Forging ratio: combined forging ratio for upsetting + drawing ≥ 4:1, ensuring grain refinement and a dense microstructure
Cooling method: air cooling after forging to room temperature to prepare for subsequent solution treatment
The mechanical properties of 17-4PH are achieved through a two-step heat treatment: “solution treatment + aging treatment.” The H1150 condition is aged at approximately 621°C for 4 hours and air cooled; it is an engineering-preferred solution that balances strength and toughness.
Heat and hold at 1038–1040°C, then cool to below 32°C to ensure complete martensitic transformation. Parts with a cross-section less than 75 mm may be liquid quenched; for larger cross-sections, rapid air cooling is recommended. The hardness in the solution-treated condition is approximately HB 330–360 (≤38 HRC); at this stage, the material has good ductility and is easy to machine.
Hold at 621°C ± 8°C for 4 hours, then air cool. This process causes copper-rich phases and carbides to precipitate uniformly in the matrix, yielding the following typical mechanical properties (ASTM A564 / AMS 5643 minimum values):
Property | H1150 Typical Value |
|---|---|
0.2% yield strength | ≥ 725 MPa (105 ksi) |
Tensile strength | ≥ 930 MPa (135 ksi) |
Elongation (4D) | ≥ 16% |
Reduction of area | ≥ 50% |
Hardness | 28–37 HRC |
Room-temperature impact energy (Charpy V) | ≥ 75 J (55 ft-lbf) |
The “GLOBAL1200” under Global Offshore (Tianjin Global Offshore) is a 1200-tonne heavy-lift pipelay vessel equipped with an S-lay stinger, capable of operating in water depths up to 3000 m and featuring DP2–DP3 dynamic positioning capability. As the core equipment of the S-lay pipelay system, the 1000-tonne stinger performs the key functions of guiding the pipeline into the water and controlling pipeline bending stress. The stinger is subjected to alternating loads over long periods, making structural fatigue failure an issue requiring special attention.
Stinger connecting shafts and pin components face three challenges: high mechanical loads, seawater corrosion, and the risk of fatigue and stress corrosion cracking under alternating stress. 17-4PH H1150 forgings offer targeted advantages in all three areas:
Strength assurance: Yield strength ≥ 725 MPa, meeting the high load-bearing requirements of large stinger pins.
Toughness advantage: The impact energy of the H1150 condition is more than 10 times that of the H900 condition, effectively resisting dynamic loads and low-temperature impact.
Stress corrosion resistance: NACE MR0175/ISO 15156 specifies a maximum hardness of 33 HRC for 17-4PH in sour environments, and H1150D is the only condition unconditionally accepted.
Seawater corrosion resistance: 17-4PH has good corrosion resistance in marine environments and has been widely used in pump shafts, valve stems, and marine propulsion shafting.
In addition to stinger shaft components, 17-4PH H1150 forgings are also widely used in:
Offshore platform valve bodies and stems, and pump shafts
Oil and gas downhole tools and wellhead equipment
Main steam isolation valve stems for nuclear power plants
Aerospace high-strength bolts and structural components
Hydraulic system valve bodies, couplings, and wear rings
What is the difference between 17-4PH H1150 and H900? How should one choose between them?
H900 is aged at 480°C, with a tensile strength of ≥ 1310 MPa and hardness of ≥ 40 HRC, making it suitable for small cross-section parts where ultimate strength is required. H1150 is aged at 621°C, with a tensile strength of ≥ 930 MPa and hardness of 28–37 HRC, but its impact toughness is far superior to that of H900, and it meets the NACE MR0175 sulfide stress cracking resistance requirements. For offshore engineering parts subjected to alternating loads and corrosive environments, H1150 is the safer choice.
What is the difference between H1150, H1150D, and H1150M?
H1150 is single aging (621°C/4 h); H1150D is double aging (621°C/4 h + 621°C/4 h), which further reduces hardness to ≤ 255 HB and is the only 17-4PH condition unconditionally accepted by NACE MR0175; H1150M is an overaging treatment (760°C + 621°C), providing the highest toughness and stress corrosion resistance.
Can forgings be supplied with third-party certification?
Yes. According to project requirements, 3.1/3.2 certificates from classification societies such as DNV, ABS, and BV can be provided, as well as NACE MR0175 compliance statements and complete mechanical property test reports (tensile, impact, hardness).
What is the maximum supply size of 17-4PH forgings?
Peeled forged bar diameters can cover 95.2 mm to 600 mm; larger sizes can be customized according to project requirements. A forging ratio of ≥ 4:1 ensures microstructural uniformity in large cross-section forgings.
What is the service temperature range of H1150 shaft parts in a marine environment?
The conventional service temperature range is -80°C to 316°C. The H1150D double-aged condition can be extended to -196°C for cryogenic service. During design, note that when the section diameter exceeds 25 mm, an appropriate design allowance for toughness margin should be considered.
