AISI H11 Tool Steel | DIN1.2343 | SKD6

H11 steel is a medium-carbon medium-chromium hot work tool steel, which belongs to the grade in the American ASTM A681 standard (corresponding to the European standard DIN 1.2343 steel, but the composition of the two is slightly different).

H11 steel is well-known for its excellent thermal fatigue resistance, good toughness and high temperature strength in the hot work tool steel family, making it one of the preferred materials for aluminum, magnesium, zinc alloy die-casting molds, as well as medium-temperature hot forging and hot extrusion molds, especially suitable for use under medium temperature (about 600°C or below) working conditions.

H11 steel performs well in mold applications that need to withstand severe thermal cycle shock. Its good hardenability (suitable for air cooling) also reduces the risk of heat treatment deformation and cracking. Choosing the right quenching and tempering process is the key to fully realizing its performance.

CHEMICAL COMPOSITION：H11 & EQUIVALENT GRADE

Standard	Grade	C	Si	Mn	P	S	Cr	V	Mo
ASTM A681	H11	0.33-0.43	0.8-1.25	0.2-0.6	0.03	0.03	4.75-5.5	0.3-0.6	1.1-1.6
DIN ISO 4957	1.2343	0.28-0.35	0.8-1.2	0.1-0.4	0.03	0.03	2.7-3.2	0.4-0.7	1.1-1.5
JIS G4404	SKD6	0.32-0.42	0.8-1.2	0.5	0.03	0.03	4.5-5.5	0.3-0.5	1.0-1.5
BS 4659	BH11	0.32-0.40	0.85-1.15	0.4	0.35	0.35	4.75-5.25	0.3-0.5	1.25-1.75

Comparison with H13 steel:

H13 is a variation of H11, the main difference being that H13 contains higher vanadium (0.80-1.20%).
Result: H13 generally has higher wear resistance, better high temperature strength and thermal stability (especially above 600°C), but is generally slightly less tough than H11 and has a slightly higher cost.
Selection: H11 is an excellent choice for cost-sensitive applications with extremely high thermal fatigue resistance, high toughness requirements, operating temperatures below 600°C. For applications with extremely high wear resistance requirements and higher operating temperatures (above 600°C), H13 may be more suitable.

H11 STEEL PHYSICAL PROPERTY

Temperature	20°C	200°C	400°C	600°C
Density,kg/m3	7800	7750	7700	7600
Modulus of elasticity,Mpa	210000	200000	180000	140000
Coefficient of thermal expansion from 20°C,per °C	—	11.6 x 10^-6	12.4 x 10^-6	13.2 x 10^-6
Thermal conductivity,W/m °C	—	30	30	31

H11 STEEL FORGING

Heating temperature: 1120-1150℃, maximum not exceeding 1180℃, to prevent overburning and grain coarsening.
Initial forging temperature: 1100-1130℃, to ensure sufficient plasticity and avoid cracking.
Final forging temperature: ≥900℃, strictly prohibited to be lower than 850℃! Low temperature forging is prone to cracks (due to the precipitation of carbides to increase deformation resistance).
Forging Ratio：above 4:1
Post-Forging Treatment:For H11 steel, Slow cooling after sand burying for 24h, then air cooling. Annealing must be performed after forging (780-800℃×4h → ≤30℃/h furnace cooling to 500℃) to eliminate stress and prepare for subsequent processing and heat treatment.

H11 STEEL HEAT TREATMENT

The heat treatment process of H11 steel is the key to its performance, especially its air-cooled hardenability and secondary hardening effect. The following introduces two common heat treatment processes of H11.

H11 Steel Annealing

Annealing of H11 steel is generally carried out after forging and before processing. Usually heated to 840-900°C, fully kept warm (about 2-4 hours/inch thickness), slowly cooled to below 500°C in the furnace, and then air-cooled to room temperature. Hardness after annealing: 192-229 HB (≈HRC 10-20).

H11 Steel Quenching

Preheating:
-First preheating: 500-550℃ (reduce thermal stress and prevent cracking)
-Second preheating: 800-850℃ (balance internal and external temperatures)
-Each stage holding time ≥ workpiece heat penetration time (usually 0.5-1 hour/inch)
Austenitizing temperature:
-Standard range: 1000-1030℃ (commonly used 1020℃)
-High temperature tendency: 1030℃↑ → dissolve more carbides → improve high temperature strength, but slightly reduce toughness.
-Low temperature tendency: 1000℃↓ → retain more undissolved carbides → wear resistance↑, toughness↑.
Holding time:
-Salt bath furnace: 5-15 minutes/inch
-Box furnace: 20-30 minutes/inch (need to prevent decarburization)
Cooling method:
–Preferred air cooling (static/forced air cooling) → small deformation, suitable for complex molds.
-Oil cooling can be used for large cross-section or high-demand parts (cracking risk↑, need to be strictly controlled).

H11 Steel Tempering

Adequate tempering is a must! Usually done in the 540-650°C temperature range, at least twice (sometimes three times), with adequate holding time each time (usually 2 hours per inch of thickness).

The tempering temperature is selected based on the required hardness (the target hardness is usually in the HRC 45-52 range). A secondary hardening peak occurs when tempering at about 540-580°C. Adequate tempering is key to achieving optimal toughness and thermal fatigue resistance.

Tempering temperature (°C)	Expected hardness(HRC)	Applicable scenarios
540-560°C	50-52	High wear resistance requirements (such as extrusion dies)
580-600°C	47-49	Balance wear resistance and toughness (die casting dies)
620-650°C	42-45	High impact toughness (hot forging dies)

Note: H11 steel should avoid tempering in the range of about 370-425°C to prevent temper brittleness.

H11 Steel Mechanical Property

Hardness,HRC	45	46.5	48.5
Tensile strength,Mpa	1450	1580	1680
Yield strength Rp 0.2,Mpa	1240	1340	1410
Elongation A5 ,%	13	13	12
Reduction in area Z,%	65	65	64

Tempering,℃	100	200	300	400	500	550	600	650	700
HRC	53	52	52	52	54	52	48	38	30
Rm,N/mm2	1845	1790	1790	1790	1910	1790	1570	1200	970

H11 STEEL MAIN APPLICATION AREAS

Die-casting molds: Especially suitable for aluminum alloy, magnesium alloy die-casting molds (such as cores, cavities, sliders, gate sleeves, etc.), and zinc alloy die-casting molds. Its excellent thermal fatigue resistance is crucial in such applications.
Hot extrusion molds: Dies used for extrusion of aluminum, copper alloys and other non-ferrous metals (such as extrusion barrel liners, extrusion pads, die supports, die sleeves, front ends of extrusion rods, etc.).
Hot forging molds: Suitable for forging dies with not particularly large forging forces and medium working temperatures (such as hammer forging dies, inserts of press forging dies, core rods, etc.).
Hot shear blades: Blades used to shear bars or billets at high temperatures.
Plastic molds (parts requiring high wear resistance and high corrosion resistance): Although it is not a mainstream plastic mold steel, it can be used to manufacture plastic mold parts that require high wear resistance, corrosion resistance or need to withstand a certain temperature (such as wear-resistant inserts of injection molds, runner systems of high-temperature plastics, etc.).
Others: core rod, hot punch, hot piercing plug, etc.