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Eternal
13-8PH is a martensitic precipitation-hardening stainless steel. Its commercial names are 13-8PH or XM-13, and its UNS number is S13800. This material is produced by a double vacuum melting process (VIM + VAR), which gives it high purity.
13-8PH forgings achieve ultra-high strength through aluminum (Al) precipitation hardening. It also offers excellent fracture toughness, good transverse mechanical properties, and outstanding resistance to stress corrosion cracking. It is one of the best-performing grades in the precipitation-hardening stainless steel family. It is especially suitable for applications that require high tensile strength, toughness, and resistance to seawater or marine atmosphere corrosion. Its service temperature ranges from -196°C to 540°C, and it maintains good toughness at low temperatures.
Jiangyin Eternal Heavy Industry Co., Ltd. can produce forged bars, square bars, ring forgings, and custom-shaped forgings. These are shaped by open-die forging or closed-die forging. We can deliver the products in the solution-annealed condition (Condition A) or after aging treatment (e.g., H950, H1000), according to customer requirements.
Element | % | Remark |
C | ≤0.05 | Reduce the tendency of intergranular carbide precipitation |
Si | ≤0.10 | |
Mn | ≤0.20 | |
P | ≤0.010 | Extremely low phosphorus content ensures purity |
S | ≤0.008 | Extremely low sulfur content ensures purity |
Cr | 12.25~13.25 | Ensure corrosion resistance |
Ni | 7.5~8.5 | Forming a precipitation strengthening phase with Al |
Mo | 2.0~2.5 | Improve the resistance to pitting corrosion |
Al | 0.90~1.35 | Mainly concentrated and strengthened elements |
N | ≤0.01 | |
Fe | Bal. | — |
Melting process:
First, vacuum induction melting (VIM) is used for primary melting. Then, vacuum arc remelting (VAR) is used for secondary refining. This effectively removes gases (oxygen, hydrogen, nitrogen) and non-metallic inclusions from the steel, which improves purity. For high-end batches, the process can also be VIM + ESR (electroslag remelting).
Sulfur content is controlled to ≤0.005%. Inclusion ratings are evaluated according to ASTM E45 standard. Fine inclusions are ≤1.5, and coarse inclusions are ≤1.0.
Country | Standard | Grade |
America | UNS | S13800 |
America | AISI/ASTM | XM-13 |
America | commercial | 13-8MoPH、13-8PH |
China GB | new | 04Cr13Ni8Mo2Al |
China GB | old | 0Cr13Ni8Mo2Al |
Germany | WNr | 1.4534 |
PH13-8Mo has the standard steel code XM-13 (UNS S13800) in the American standard system, and the same steel code in China is 04Cr13Ni8Mo2Al. This grade has largely replaced 17-4PH abroad and is widely used in aerospace, nuclear industry and petrochemical fields.
aged condition | tensile strength （MPa） | yield strength （MPa） | elongation （%） | hardness（HRC） |
Condition A（solution） | — | — | — | ≤38 |
H950 | ≥1517 | ≥1413 | — | 45~47 |
H1000 | — | — | — | 43 |
H1050 | ≥1310 | ≥1240 | ≥15 | 40 |
Note: Under H1050 condition, the elongation is ≥ 15% (with a 50mm gauge length), and the Charpy impact energy is ≥ 81J.
The initial smelting is carried out by vacuum induction melting (VIM), followed by secondary refining through vacuum self-dissolution remelting (VAR). Alternatively, the VIM + ESR (electroslag remelting) process can also be adopted..
Optimal forging temperature range: 1170 - 1205℃
Final forging temperature: ≥ 954℃ (1750℉)
Temperature: 925 ± 15℃ (927℃ ± 8℃)
Heating time: 15 to 30 minutes (adjustable according to the cross-sectional size)
Cooling method: Air cooling or oil cooling to room temperature
Aged condition:H950、H1000、H1050、H1150M
Time :4H
Cooling :air
Condition | Description |
圆钢 | Φ12～Φ400mm L2000～6000mm |
方钢 | 20×20mm ～ 300×300mm |
环形 | Φ200～1500mm Height:20～300mm |
Condition A（固溶退火态） | 925±15℃→ Air cooling / Oil cooling，Hardness≤HRC 38 |
Solution condition | H950/H1000/H1025/H1050/H1100/H1150 |
as-forged delivery | The original surface after forging |
Rough machining | roughness Ra1.6-3.2μm，dimension accuracy ±0.5mm |
Polish | Outer surface grinding / peeling grinding, without decarburization layer, without cracks，Ra≤1.6μm |
Thanks to its ultra-high strength, excellent fracture toughness, good transverse properties, and outstanding stress corrosion resistance in marine environments, 13-8MoPH forgings are widely used in many industries. In aerospace, they are used for critical structural parts such as angle boxes, brackets, lugs, connecting plates, spring plates, load-bearing frames, wing beams, landing gear components, main load-bearing frame forgings, cold-headed fasteners, and missile structures. In the nuclear industry, they are applied to reactor containment and structural parts. In petrochemicals, they serve in high-pressure pumps, valves, bodies, seats, and other equipment. For marine engineering, they are used in offshore platform structures and corrosion-resistant components. Other applications include precision instruments, high-end molds, and injection molding equipment.
Q1: What are the advantages of PH13-8Mo forgings compared to 17-4PH?
A: PH13-8Mo has better overall performance than 17-4PH. It has better transverse mechanical properties (higher transverse reduction of area), better resistance to stress corrosion cracking, and better pitting resistance because of the molybdenum addition. So 13-8MoPH has largely replaced 17-4PH in many foreign applications.
Q2: How is the corrosion resistance of 13-8MoPH?
A: 13-8MoPH has better corrosion resistance than 1Cr13 and 1Cr17Ni2 (431) martensitic stainless steels. Compared with 17-4PH and 15-5PH, it has better pitting resistance due to molybdenum. Like other precipitation-hardening stainless steels, it has the best corrosion resistance in the fully hardened condition.
Q3: Does 13-8MoPH have hydrogen embrittlement problems?
A: Under severe test conditions, 13-8MoPH aged at temperatures below 565°C is somewhat sensitive to hydrogen embrittlement. But in actual service, hydrogen embrittlement failures are very rare. When aged at temperatures above 595°C, it is immune to hydrogen-induced cracking.
Q4: Why is double vacuum melting recommended for 13-8MoPH forgings?
A: Using VIM+VAR (vacuum induction melting + vacuum arc remelting) helps to precisely control the chemical composition, reduce gas content, and improve purity. This is important for ensuring good transverse mechanical properties and fracture toughness.
Q5: What if 13-8MoPH forgings are difficult to machine?
A: After solution treatment + cold treatment + artificial aging, the hardness can reach up to 45 HRC, making machining difficult and causing severe tool wear. It is recommended to do rough machining in the H1150M overaged condition, then solution treat and age before finish machining. Alternatively, most machining can be done in the softer Condition A (solution-treated state).
Q6: What is the delivery time for 13-8MoPH forgings?
A: Forgings are custom products. The production time depends on the size, complexity, and order quantity. It is best to discuss technical requirements (delivery condition, dimensions, quality standards, inspection levels, etc.) with the supplier in advance.
Q7: How is the quality of 13-8MoPH forgings ensured?
A: Each batch should include: ① spectrochemical analysis report (chemical composition); ② mechanical property test report; ③ ultrasonic inspection report; ④ dimensional inspection report. For high-end applications, it is recommended to ask a third-party inspection agency (TUV/SGS/BV) to issue test certificates.
