S7 Tool Steel
S7 mould steel is a high-toughness, impact-resistant chromium-molybdenum alloy tool steel, primarily employed in the manufacture of forging dies, hammers, chisels, and jig moulds.
Product Description
Xiri Tool Steel is a leading supplier of S7 tool steel in China. S7 is a type of air-cooled quenched tool steel with extremely high toughness and good wear resistance. It is hailed as the “King of Toughness” and is particularly suitable for cold and hot working molds that are subjected to extreme impacts and heavy loads.
Whether you need S7 flat bars, S7 steel plates, or forged rounds, we provide custom dimensions with machining or grinding services. Our materials are strictly tested to ensure premium metallurgical structure.
S7 mould steel is a high-toughness, impact-resistant chromium-molybdenum alloy tool steel, primarily employed in the manufacture of forging dies, hammers, chisels, and jig moulds.
Chemical Composition of AISI S7 tool steel
| C | Si | Mn | Cr | P | S | Mo | V |
| 0.45-0.55 | 0.20-1.00 | 0.20-0.90 | 3.00-3.50 | max 0.030 | max 0.030 | 1.30-1.80 | max 0.35 |
Supply Form & Size Range of AISI S7 tool steel
We supply S7 steel in various forms to meet your manufacturing needs:
Round bar: Diameter 16mm – 800mm
Steel Plate / Flat: Thickness 10mm – 400mm x Width 100mm – 800mm
Surface: Black, Peeled, Rough machined or Grinded.
Delivery Condition: Annealed (Hardness 217 HB max.)
Exceptional Performance of S7 Tool Steel
Unrivalled Toughness: S7’s most notable advantage lies in its exceptional impact resistance. Even at its maximum hardness (e.g., HRC 60), it withstands immense impact loads without chipping or fracturing. This makes it ideal for manufacturing impact-prone components such as hammer forging dies, punching dies, punches, and impact rods, significantly reducing the risk of brittle failure.
Superior Thermal Fatigue Resistance: During repeated heating and cooling cycles, conventional steels are prone to cracking due to accumulated thermal stresses (thermal fatigue cracks). S7 steel possesses excellent high-temperature strength and thermal conductivity, effectively resisting such thermal stress cycles. It maintains surface finish and dimensional stability, substantially extending tool life in hot working environments (e.g., die casting, hot extrusion).
Outstanding resistance to softening (red hardness): Moulds operating at elevated temperatures often experience surface hardness degradation (softening) due to heat exposure, leading to deformation and accelerated wear. S7 maintains considerable hardness even at high temperatures (e.g., around 500°C). This red hardness ensures the mould retains sharpness and contour precision after sustained high-temperature operation.
Outstanding wear resistance balanced with machinability: While delivering high hardness and toughness, S7 also exhibits excellent wear resistance and achieves high surface finish through precision grinding. Its annealed state offers good machinability with relatively low heat treatment distortion, facilitating mould fabrication and repair.
Core Application of S7 Tool Steel
S7 mould steel has proven its worth in numerous demanding applications through its unique combination of properties:
King of Impact Tools: Rock drill bits, pneumatic tool impact components, riveting dies, cold/hot punches, and punching/shearing dies. These components, subjected to repeated severe impacts, rely on S7’s toughness to prevent chipping and failure.
Guardian of High-Temperature Forming: Die-casting moulds (particularly cores for aluminium, zinc, and magnesium alloys demanding high toughness), hot-stamping dies, and hot-extrusion tools (extrusion cylinder liners, die inserts). S7’s thermal fatigue resistance and red hardness prove indispensable here.
Master of Heavy-Duty Shearing and Blanking: Medium-to-thick plate shearing blades, demanding cold blanking dies (e.g., cutting thick sheet metal or where punches face high impact), where S7 excels through its balanced strength and toughness.
Precision Wear Resistance Requirements: Bearings, bushings, precision guide components, etc., requiring moderate toughness alongside high wear resistance and superior surface finish.
Our advantages in Processing S7 Tool Steel
Selecting S7 tool steel ensures exceptional performance through rigorous control of every stage from raw materials to production. Premium S7 material adheres to these ironclad quality principles:
Top-tier Pure Raw Materials: Commencing with high-purity master alloys, strictly controlling harmful elements (sulphur, phosphorus) to eliminate inclusions at source.
Advanced Smelting Techniques: Extensive application of processes such as Electro-Slag Remelting (ESR) or Vacuum Arc Remelting (VAR). Notably, ESR technology effectively purifies molten steel, significantly reducing inclusions, refining grain size, and greatly enhancing the steel’s toughness, fatigue resistance, and hot workability. This is the core technology ensuring the stable performance of high-toughness S7 mould steel.
Precision Forging and Heat Treatment: High-tonnage forging thoroughly disrupts the original cast structure, enhancing density. Advanced controlled atmosphere heat treatment (vacuum heat treatment, protective atmosphere heat treatment) provides precise temperature control and guarantees oxidation-free, decarburisation-free processing, ensuring uniformity and consistency in final hardness and microstructure.
Comprehensive Non-Destructive Testing: 100% ultrasonic testing (UT) screens for minute internal defects (cracks, inclusions, porosity, etc.), strictly evaluated against international standards (e.g., ASTM A388).
Batch traceability and comprehensive documentation: Each S7 die steel billet must be accompanied by complete documentation including furnace batch number, heat treatment batch number, and relevant inspection reports (chemical composition analysis, mechanical property testing, flaw detection reports, etc.), ensuring full traceability throughout the quality assurance process.
Not sure about the best equivalent for your application?
Why Manufacturers Choose Huangshi Xiri
Huangshi Xiri combines international-standard steel grades, a complete tool steel portfolio, strict quality control and reliable global supply. We match DIN / JIS / AISI equivalents precisely, offer cutting and heat-treatment services, and control every step from smelting to inspection. With stable capacity, on-time delivery and responsive technical support, we help manufacturers reduce risk, save costs and run production with confidence.
Contact Us
Contact Huangshi Xiri today for quotations, grade selection and technical support on tool steel, mold steel and alloy steel. Whether you need samples, cutting-to-size service or long-term supply for your projects, our engineers and sales team are ready to respond quickly with professional advice and reliable solutions for your manufacturing needs.
