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Tool Steel H11

Tool Steel H11 is a chromium-based steel alloy from the “H” family of steels according to the AISI classification system. H11 is one of the most commonly used alloys from this group, thanks to the outstanding impact toughness. Other steels from this group, such as the H13 have more vanadium, which gives better wear resistance and temper resistance, but worse impact toughness.

Thanks to these properties, Tool Steel H11 is mostly used in the aerospace industry, more precisely for the landing gear. This alloy is also widely used for helicopter rotor blades and shafts, as well as die-casting dies.

Tool Steel H11 is also used for hot tooling applications thanks to its excellent resistance to cracking, including thermal fatigue cracking, gross cracking and thermal shock during water cooling. These include hot punches, die casting dies, forging dies, hot shear blades, hot gripper dies, and extrusion tooling. Like most steels with high toughness and low carbon content, Steel H11 can be used for producing hot-work steels with the water-cooling method.

Tool Steel H11 has minimal distortion during deep-hardening and air-hardening thanks to the balanced alloy content. H11 can also be hardened with an air quenching method.

Tech Steel & Materials offers Tool Steel H11 in four sub-type specifications and multiple shapes/forms:

Chemical Composition of Tool Steel H11

Element Min (%) Max (%)
Carbon, C 0.38 0.43
Manganese, Mn 0.20 0.40
Silicon, Si 0.80 1.00
Sulfur, S 0.015
Phosphorus, P 0.015
Chromium, Cr 4.75 5.25
Molybdenum, Mo 1.20 1.40
Vanadium, V 0.40 0.60
Nickel, Ni 0.25
Copper, Cu 0.35
Iron, Fe *Balance

*Not exclusively to the element mentioned, but that one predominates other elements that are used only in minimal quantities.

Fabrication and Working Instructions

Tool Steel H11 can be easily formed using conventional methods for machining and forging. For forging the preferred temperature is 2050° F (1121° C), with 1650° F (899° C) being the lowest recommended point. H11 can also be cold-worked and welded with conventional methods for steels in this group. That said, machinability of H11 is 75% to that of steels in the “W” group.

Mechanical and Physical Properties of Tool Steel H11

Property Imperial Metric
Density 0.282 lb/in³ 7.81 g/cc
Melting Point 2600°F 1427°C
Tensile Strength 260 ksi 1792 MPa
Tensile Strength, Yield 215 ksi 1482 MPa
Elongation in 4D 8 % 8 %
Reduction of Area 30 % 30 %
Hardness, Rockwell C
Air cooled from 1800°F (982°C) for 45 minutes)
52.5 52.5
Hardness, Rockwell C
Air cooled from 1850°F (1010°C) for 45 minutes)
56 56
Hardness, Rockwell C
Air cooled from 1900°F (1038°C) for 45 minutes)
57 57
Charpy impact
V-notch; air-cooled from 1850°F (1010°C) and then tempered at 535°C
10.0 ft-lb 13.6 J
Charpy impact
V-notch; air-cooled from 1850°F (1010°C) and then tempered at 1200°F (650°C)
20.0 ft-lb 27.1 J
Charpy impact
V-notch; air-cooled from 1850°F (1010°C) and then tempered at 700°F (370°C)
25.0 ft-lb 33.9 J
Poisson’s Ration 0.27 – 0.30 0.27 – 0.30
Machinability (relative rating for 1% Carbon Steel) 75-80 % 75-80 %

Transverse Tensile Properties

Property Imperial Metric
Tensile Strength 260 ksi 1792 MPa
Tensile Strength, Yield (0.2% Offset) 215 ksi 1482 MPa
Individual Value 6 % 6 %
Average Value 15 % 15 %

Thermal Properties of Tool Steel H11

Property Imperial Metric
Thermal Expansion
(at the temperature range of 68-112° F / 20-100° C)
6.63 µin/in°F 11.9 x 10-6/ºC
Thermal Conductivity(at 212° F / 100° C) 292.9 in/hr.ft².°F 42.2 W/mK

Heat Treatment of Tool Steel H11

Tool Steel H11 can be heat treated using various different schemes that give different properties. Heat treatments of this alloy usually consist of annealing, hardening/austenitizing, air and oil quenching, and single or double tempering at temperatures of 840° F (450° C), 930° F (500° C), 1020° F (550° C), 1110° F (600° C), and 1200° F (650° C).

According to some independent studies, the optimum heat treatment for a combination of hardness, toughness, yield strength, ultimate strength, and ductility include oil-quenching and double-tempering at 1020° F (550° C). Higher hardness can be achieved by oil-quenching and double tempering at 1110° F (600° C), but this can also lead to lower lead strength and very low ductility. Also, with the increase of hardness of Tool Steel H11, impact toughness decreases.

Select AMS Number:

AMS Number Alloy Type UNS Cross Ref. Spec Misc./Shape
AMS 6437 H11 Tool Steel T20811  
AMS 6437 Plate H11 Tool Steel T20811 - Plate AMS 6437 Plate
AMS 6437 Sheet H11 Tool Steel T20811 - Sheet AMS 6437 Sheet
AMS 6437 Strip H11 Tool Steel T20811 - Strip AMS 6437 Strip
AMS 6485 H11 Tool Steel T20811  
AMS 6485 Bar H11 Tool Steel T20811 QQ-T-750 Bar AMS 6485 Bar
AMS 6485 Forging H11 Tool Steel T20811 QQ-T-750 Forging AMS 6485 Forging
AMS 6487 H11 Tool Steel T20811  
AMS 6487 Bar H11 Tool Steel T20811 - Bar AMS 6487 Bar
AMS 6487 Forging H11 Tool Steel T20811 - Forging AMS 6487 Forging
AMS 6488 H11 Tool Steel T20811  
AMS 6488 Bar H11 Tool Steel T20811 - Bar AMS 6488 Bar
AMS 6488 Forging H11 Tool Steel T20811 - Forging AMS 6488 Forging