HY 80 / 100 Steels

HY 80 Steel

Specs: MIL-S-21952, T9074-BD-GIB-010/0300
UNS#: K31820

HY 80 is a high yield steel with a minimum yield strength of 80 ksi. While many steels offer high yield strength, HY 80 also offers exceptionally high impact strength as well. This combination makes HY 80 unique among steels. This material is used extensively in marine defense and petrochemical applications.


Wieland Diversified is the largest stocking distributor of HY 80 and HY 100 in North America; stocking a full line of round stock, while also offering gun-drilled tubing.


Certified to the MIL-S-21952 C/D and T9074-BD-GIB-010/0300.


HY is also available in ID/OD Tubing up to 22′ length.


Heat Analysis of HY 80

  •  HY 80 is a high strength low alloy martensitic steel containing small additions of chromium and nickel to help with corrosion resistance and is supplied in the Type B condition bright finish.
  • Owing to the rigorous requirements of the end application, all material is electric arc melted and vacuumed degassed with argon. All bar stock is ultrasonically tested to MIL STD 271,(NAVSEA T9074-AS-GIB-010/271) and has full Level I Subsea traceability
  • The alloy was originally designed for use in naval applications where high strength, high toughness and impact strength is required.
  • HY80 was first used by the US, UK and Australian Navy for the construction of submarine hulls where high strength and toughness was necessary to withstand water pressure at depth, but the alloy had also to exhibit excellent fabrication properties to allow the welding of complex structures.
  • The alloy has since found wider applications in the construction of pressure vessels, armor plating, the petrochemical industry and any high integrity application requiring added strength and rigorous testing requirements. 

Welding HY 80

  • Weldments of HY-80 are noted for good ductility, notch toughness and strength. It is recommended to weld using the metal-arc process with low hydrogen electrodes of Type E-10018 or E-11018. It is important to use approved weld procedures, so that the correct heat input per inch of weld bead is introduced, which would otherwise cause degradation of notch toughness.
  • Electrodes should be warmed before use to drive off any moisture to avoid hydrogen pick-up in the weld. Preheating is not required, except for very heavy section thickness welds or heavily constrained welds. Post-heating is not required but a stress relief anneal, after welding of sections of 1-1/2″ thick or greater, is desirable. However the alloy may be used in the as-welded condition.


  • High-pressure tubing can be made from HY 100 and HY 80 bars up to 30 feet in length. Tubes can be welded together to achieve longer lengths. The material’s superior combination of ductility and fracture toughness makes it a great choice for pressures as high as 14,000 PSIG operating pressure or more depending on wall thickness. The tubes have been tested up to 21,000 PSGI.
  • Typical operating temperatures are 500o F to -20o F. The tubes can be bent up to 180 degrees with a maximum allowable thinning of 10% and flattening of 8% depending on tube OD and wall thickness and will maintain their physical properties. ID surface finishes of 64 micro or greater can be achieved. Straightness tolerances of .015″ per foot can be maintained. Bars can be ultrasonically tested in immersion and/or Mag Particle tested to ensure integrity after drilling.

Available shapes –  round


Related Products


  • Pressure vessels
  • Submarine construction
  • Naval Craft construction
  • Heavy construction equipment
  • Armor plate for vehicles
  • Bank trucks
  • Guard Booths and barriers
  • Storage tanks for liquefied hydrocarbon vapors
  • Petrochemical

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Specifications of HY 80 Steel

Tube & Pipe
Sheet & Plate Rod & Bar Forgings
UNS K31820   MIL-S-16216 Rev K
MIL-S-24645 Rev A
MIL-S-24371 Rev B
MIL-S- 21952 Rev C & D
MIL-S-22664 Rev B
MIL-S -24512
MIL-S-23009 Rev C
Naval       EB 3719 Rev C
EB 2678 Rev H
EB 3132 Rev D
ASTM       A543 Grade B&C  
United Kingdom
    DEF STAN 02-736
Part 1
DEF STAN 02-736
Part 4
DEF STAN 02-736
Part 2
Mechanical Properties

Mechanical Properties of HY 80 Steel

Ultimate Tensile Strength* 0.2% Yield Strength Elong in 2″ (Min) Reduction of Area (Min) Hardness
Ksi N/mm² Ksi N/mm² % % BHN
100-120 690-827 80-99.5 552-686 20 (L) 18 (T) 55 (L) 50 (T) 230-290
Impact Properties

Impact Properties of HY 80 Steel

Test Temperature Charpy V-notch Longitudinal Charpy V-notch Transverse**
°F °c ft lbs Joules ft lbs Joules
-120 -84 50 68 50 68
0 -18 70 95 60 81

**Transverse properties only required for 4″ (100mm) dia or greater

The properties shown below are for guidance only and are not intended for specification purposes.

Physical Properties

Physical Properties of HY 80 Steel

Physical Properties Imperial Units Metric Units
Density 0.28 lb/in³ 7.83 /cm³
Melting Range 2640-2750ºF 1450-1510ºc
Mean Liner Expansion 0-200ºc   18_m/m.ºc
Mean Liner Expansion 0-400 ºF 0.010 in/in/ ºF x10³  
Specific Heat 0.11Btu/lb/ ºF 460J/kg ºc
Poisson€s ratio 0.28 0.28
Thermal Conductivity 48.18Btu-in/sec/ft²/ ºF 25W/m. ºk
Modulus of Elasticity 10³ 29ksi 200 N/mm²
Shear Modulus 10³ 11.2ksi 77 N/mm²

The data is believed to be accurate but Diversified Metals Inc makes no representation or warranty of any kind (expressed or implied) and assumes no responsibility with respect to its accuracy and values should only be used as a guide.

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