PH 13-8MO Stainless Steel

Typical Applications

Fasteners

Valves

Fittings

Petrochemical Components

Aircraft Structural parts

AMS 5629, AMS 5864 Suppliers and Stockholders

Dynamic Metals is a specialist supplier and stockholder of PH 13-8 Mo stainless steel, supplying aerospace and high-performance industries with certified material to AMS 5629 and AMS 5864 since 1997. No minimum order quantities.

PH 13-8 Mo is a martensitic precipitation hardening stainless steel with specification AMS 5629 and AMS 5864. This material boasts an excellent combination of strength, toughness and outstanding resistance to stress corrosion cracking; hence being one of the most efficient types within the precipitation hardening stainless steels group.

Strength is imparted to the material through ageing process and the tensile strength varies from 931 MPa in H1150 condition up to 1517 MPa in H950 — some of the highest figures in wrought stainless steels group. These characteristics are retained at both room and elevated temperatures; therefore, PH 13-8 Mo is applicable for numerous engineering uses.

High resistance to stress corrosion cracking becomes particularly important when it comes to application in corrosive environment under mechanical loads – these features are common in such areas as aerospace structural fittings, petrochemical parts and fasteners. The alloy is manufactured through Vacuum Induction Melting (VIM) and Vacuum Arc Remelting (VAR); these processes ensure high level of purity of the material.

The alloy should be machined with proper equipment and cutting conditions; PH 13-8 Mo should be used in solution annealed state and afterwards aged in order to obtain correct dimensions of the parts.

Related Products

Key Features and Benefits

Fracture toughness (KIC) ~110 MPa√m

Superior stress corrosion cracking resistance due to high nickel (7.50-8.50%) and molybdenum (2.00-2.50%) content

Tensile strength 931-1517 MPa across H950 to H1150 conditions

Mandatory VIM/VAR production ensures material cleanliness critical for safety-critical aerospace applications

Excellent transverse mechanical properties due to vacuum melting — important for structural fittings and fasteners

Technical specification

Related Specifications

AMS 5629
AMS 5864
UNS S13800
W.Nr 1.4534

Specific Gravity

7.76 g/cm3

Chemical Composition (WT %)

 
Min  
Max  
C  
-  
0.05  
Si  
-  
0.10  
Mn  
-  
0.10  
P  
-  
0.01  
S  
-  
0.008  
Cr  
12.24  
13.25  
Mo  
2.00  
2.50  
Ni  
7.50  
8.50  
AI  
0.90  
1.35  
N  
-  
0.010  
Fe  
Bal  
-  

Typical Mechanical Properties in the Annealed condition

 
 
 
H950  
H1000  
H1025  
H1050  
H1100  
H1150  
0.2% Proof Stress  
MPA  
Min  
1413  
1310  
1207  
1138  
931  
621  
Tensile Strength  
MPA  
Min  
1517  
1413  
1276  
1207  
1034  
931  
Elongation  
%  
Min  
10  
10  
11  
12  
14  
14  
Reduction of area  
%  
Min  
45  
60  
50  
50  
50  
50  
Reduction of area  
%  
Min  
35  
40  
45  
45  
50  
50  
Hardness  
HRC  
Min  
45  
43  
41  
40  
34  
30  

Applications

This material excels in demanding environments, particularly in:

  • Aircraft structural fittings where fracture toughness is as critical as yield strength
  • Aerospace fasteners in safety-critical assemblies requiring SCC resistance
  • Petrochemical valves and fittings operating under sustained load in corrosive media
  • Landing gear components requiring high strength with crack tolerance
  • Helicopter rotor hubs and rotating structural components
  • Defence structural fittings requiring maximum toughness at high strength

Performance Characteristics

  • Tensile strength up to 1517 MPa (H950) — among the highest available in any wrought stainless steel
  • Fracture toughness KIC ~110 MPa√m — significantly superior to 17-4 PH at equivalent strength
  • Hardness range 30 HRC (H1150) to 45 HRC (H950) — selectable through ageing condition
  • Properties retained at elevated temperatures and down to cryogenic conditions
  • Elongation minimum 10% maintained even in highest strength H950 condition
  • Reduction of area minimum 45% in H950 — confirms genuine toughness at maximum strength

Corrosion Resistance

  • Outstanding stress corrosion cracking resistance 
  • Higher molybdenum content (2.00-2.50%) provides improved pitting resistance in chloride environments
  • Suitable for marine, coastal aerospace, and chemical processing environments
  • Performs reliably under combined mechanical loading and corrosive exposure
  • Forms stable passive oxide layer resistant to a broad range of corrosive media

Melting and Material Quality

  • Produced exclusively by Vacuum Induction Melting (VIM) followed by Vacuum Arc Remelting (VAR)
  • VIM/VAR process eliminates non-metallic inclusions that would reduce toughness
  • Consistent chemistry and microstructure across the full bar cross-section
  • Superior transverse mechanical properties versus conventionally melted grades
  • Full material certification traceable to original melt heat
  • Complies with AMS 5629 and AMS 5864 chemistry and property requirements

Machining and Processing

  • Machine in solution annealed condition before final age hardening
  • Lower work hardening rate than austenitic stainless steels — more predictable machining behaviour
  • Age harden after machining to final dimensions — typically H950 to H1150 depending on application
  • Welding possible but requires care — strain age cracking risk in aged condition
  • Weld in solution annealed condition, re-solution treat and age after welding for critical joints
  • Dimensional change during ageing is minimal — allows tight tolerances to be maintained

Available Forms

  • Bar — AMS 5629 (primary bar specification)
  • Available in a range of round bar diameters for machined components
  • Supplied in solution annealed condition ready for customer age hardening
  • No minimum order quantities on stock items
  • Suitable for both prototype development and production volumes

Advantages of PH 13-8 Mo

  • Combines maximum strength with fracture toughness rarely achieved in stainless steels — making it suitable for the most demanding safety-critical applications
  • Superior stress corrosion cracking resistance compared to 17-4 PH and 15-5 PH — extends component life in aggressive environments
  • VIM/VAR production provides consistency and cleanliness that conventional melting cannot match
  • Engineer selectable strength — H950 to H1150 ageing conditions allow tailoring of properties to specific application requirements
  • Excellent transverse properties make it suitable for components loaded in multiple directions — unlike many high strength steels
  • Machines in soft annealed condition before hardening — complex geometries achievable before final ageing
  • Minimal distortion during age hardening — tight dimensional tolerances maintained through heat treatment
  • One of the few stainless steels combining high strength, toughness and corrosion resistance in a single alloy

Why Choose Dynamic Metals?

  • Specialist supplier of PH 13-8 Mo since 1997
  • AS9100 certified — full quality management system in place
  • Complete material certification with traceability to original VIM/VAR heat
  • No minimum order quantities on stock items
  • Materials engineering team available to advise on heat treatment and application
  • Fast UK delivery on standard stock sizes

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