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Eternal
A8 die steel (AISI A8 / ASTM A681 Type A8) is a medium-carbon air-hardening cold-work die steel under US standard ASTM A681. Jiangyin Eternal Heavy Industry Co., Ltd. uses good electric furnace melting + refining process, and forges by large forging equipment to give you A8 die steel forgings with dense structure and good performance.
A8 is known for its great toughness, good hardenability, and excellent size stability during heat treatment. It holds a special place among cold-work die steels — its toughness is better than D2/SKD11 (high-carbon high-chromium steels), and its wear resistance is better than S7 (impact-resistant steels).
Element | Content(wt%) | Description |
C | 0.50-0.60 | Ensure high hardness and wear resistance after quenching |
Si | 0.75-1.10 | Decarburizing agent, enhances hardenability |
Mn | 0.20-0.50 | Improve hardenability to enhance strength and hardenability |
P | ≤ 0.030 | Harmful elements, strictly controlled |
S | ≤ 0.030 | Harmful elements, strictly controlled |
Cr | 4.75-5.50 | Improve hardenability, wear resistance and corrosion resistance |
Mo | 1.15-1.65 | Refine the grains and enhance the toughness |
V | 1.00-1.50 | Refine the crystal grains to enhance the wear resistance and toughness |
W | 1.00-1.50 | Improve the wear resistance and hardenability of steel |
 | Standard | Grade |
ISO | - | |
GB | 5Cr5WMoSi | |
JIS | SKD12（similar） | |
DIN | 1.2631 | |
EN | 1.2363 | |
AISI | A8 |
Supply condition hardness
Condition | Hardness | Standard |
Soft Annealed(+A) | ≤229HB | ASTM A681-24 |
Heat Treatment
Process | Parameter |
Annealing | 870-890℃，≤30℃/h slow cold to 500℃，Out-of-oven air cooling；annealled hardness≤229HB |
Quenching (Austenitization) | 1000-1050℃，air cooling、oil cooling or wind cooling |
Quenching hardness | 59-62 HRC |
Tempering | 300-600°F（about150-315℃）；Above 900°F Recommend double tempering |
Electric arc furnace (EAF) + LF refining + VD vacuum degassing. For high-end requirements, electroslag remelting (ESR) can be adopted to enhance purity.
The initial forging temperature is 1100℃, and the final forging temperature is 900℃.
The annealing process is generally spherical annealing. Usually, the steel is heated to 820-870℃ and then slowly cooled to obtain a uniform spherical pearlite structure.
Our company can provide complete quality documents such as ultrasonic testing reports, material certificates, and mechanical performance reports according to customer requirements.
Each heat of steel is analyzed before pouring to make sure the chemical composition meets ASTM A681-24 Table 1. Product analysis reports can be provided if the customer asks for them.
The product is checked in the annealed condition using macroscopic examination (according to Practice A561). This ensures there are no harmful defects like too much porosity, segregation, non‑metallic inclusions, pipe, cracks, etc.
Annealed hardness: not more than 229 HB
Hardness after quenching and tempering: not less than 59 HRC
Ultrasonic inspection (Supplementary Requirement S1)
Inclusion rating (according to Test Methods E45, Supplementary Requirement S2)
Froduct form | Size | surface state |
forged round bar | Diameter 200-1500mm | as-forged condition or rough manchined |
Forged billet | within 20 tons | as-forged condition or rough manchined |
Forged step shaft | Customized according to OEM requirements | as-forged condition or rough manchined |
Forged disk | Diameter 200-1500mm | as-forged condition or rough manchined |
Forged tube | Max OD 1500mm | as-forged condition or rough manchined |
Forging special-shaped parts | Customized according to OEM requirements | as-forged condition or rough manchined |
A8 die steel forgings are widely used in:
Cold work dies: precision stamping dies, drawing dies, blanking dies with complex shapes.
Cold forging dies: cold forging dies, cold extrusion dies (hardness 55–60 HRC).
Punches: high-speed heading punches, precision punches.
Shearing tools: cold and hot shearing blades and knives.
Thread rolling dies: thread rolling dies for screws, forming rolls.
Deep drawing dies: stainless steel stamping dies, deep drawing forming dies.
Woodworking tools: long-life wear-resistant woodworking tools.
Problem 1: Mold chipping and cracking happen often.
A8 solution: A8 has twice the toughness of SKD11 cold-work steel. For complex or precision stamping and drawing dies, it resists cracking and chipping much better. For cold forging dies and punches under high impact load, A8 is a good choice.
Problem 2: Mold cracks after wire cutting (EDM).
A8 solution: After tempering at 520–530°C, A8 still has hardness 61–63 HRC. This lowers the risk of cracking from residual stress during wire cutting. For molds that need EDM after heat treatment, A8's size stability and low stress are very important.
Problem 3: Big heat treatment distortion and unstable size.
A8 solution: A8 is air-hardening steel. It gives uniform hardness and structure even in large sections. During heat treatment, size change is very small. This is good for precision mold making.
Problem 4: Short mold life and frequent replacement.
A8 solution: A8 works well with surface hardening like gas nitriding or soft nitriding. This can increase mold life. After gas nitriding at 525°C, surface hardness can reach about 1250 HV.
Bulk export price (FOB): about $900–$2,100/ton, depending on order quantity, size, and machining precision.
Domestic retail spot price: about $13,300–$14,600/ton, tax included, suitable for small-quantity purchases.
Forgings / custom-machined parts: usually 20–50% above the above prices; exact price depends on drawings and requires a quotation.
