ThePipingMart Blog Grades A9 Tool Steel (UNS T30109) – Composition, Properties and Uses

A9 Tool Steel (UNS T30109) – Composition, Properties and Uses

Tool Steel A9

Tool Steel A9 is a high-carbon, air-hardened steel that is commonly used in the manufacture of tools. This type of tool steel has excellent wear resistance, making it ideal for applications where edge retention is important. In addition to its wear resistance, Tool Steel A9 also offers good toughness and machinability, as well as excellent heat treatment and corrosion resistance. A9 Tool Steel (UNS T30109) is a high-performance tool steel known for its exceptional strength, hardness, and toughness. It is commonly used in various industrial applications where extreme conditions are a concern. The composition of A9 Tool Steel includes high levels of chromium, molybdenum, and vanadium, allowing it to resist wear and deformation even at elevated temperatures. It also has excellent resistance to corrosion and fatigue, making it a popular choice for demanding industries such as aerospace, automotive, and cutting tool manufacturing. With its impressive combination of strength, hardness, and toughness, A9 Tool Steel is a reliable choice for any application requiring the highest performance level. Let’s take a look at some of the uses, properties, and machining of this valuable tool steel.

What Forms of A9 Tool Steel is Available at Piping Mart?

  • Nut
  • Bar
  • Bolt
  • Pipe
  • Screw
  • Tubing
  • Valves
  • Washers
  • Flanges
  • Fasteners
  • Electrodes
  • Stud Bolts
  • Sheet Plates
  • Pipe Fittings
  • Forged Fitting
  • Instrumentation Fittings

A9 Tool Steel Composition

Element Content (%)
C 0.45-0.55
Mn 0.5
Si 0.95-1.15
Cr 4.75-5.50
Ni 1.25-1.75
Mo 1.30-1.80
V 0.80-1.40
Cu 0.25
P 0.03
S 0.03

A9 Tool Steel Physical Properties

Properties Metric Imperial
Density 7.78 g/cm3 0.281 lb/in3

A9 Tool Steel Mechanical Properties

Properties Metric Imperial
Hardness, Knoop (converted from Rockwell C hardness) 662 662
Hardness, Rockwell C (tempered at 500°C) 57 57
Hardness, vickers 641 641
Tensile strength, ultimate (tempered at 500°C) 2200 MPa 319000 psi
Tensile strength, yield (tempered at 500°C) 1780 MPa 258000 psi
Elongation at break (in 50 mm; tempered at 500°C) 5.00% 5.00%
Izod impact (smooth bar; tempered at 500°C) 18.0 J 13.3 ft-lb
Poisson’s ratio 0.27-0.30 0.27-0.30
Elastic modulus 190-210 GPa 27557-30457 ksi

A9 Tool Steel Thermal Properties

Properties Conditions
T (°C) Treatment
Thermal expansion 12 x 10-6/ºC 20-425

A9 Tool Steel Equivalents

  • ASTM A681
  • FED QQ-T-570
  • UNS T30104

A9 Tool Steel Uses

Tool Steel A9 is often used in the manufacture of cutting tools such as knives, punches, shears, chisels and drill bits due to its superior edge retention. It can also be used for various other applications, including dies and forming tools such as heading dies, thread rolling dies and extrusion mandrels.

A9 Tool Steel Uses in Industries

Automotive Industry

A9 tool steel is commonly used in the automotive industry for its high strength and durability. It is often used to make engine components, such as crankshafts, gears, and suspension and steering parts. The use of A9 tool steel in the automotive industry helps to improve the overall performance and reliability of vehicles.

Aerospace Industry

The aerospace industry also utilizes A9 tool steel for its high strength and resistance to wear and corrosion. It is commonly used to make critical components for aircraft engines, landing gear, and other structural parts. A9 tool steel’s ability to withstand extreme temperatures makes it an ideal material for this industry.

Manufacturing Industry

A9 tool steel makes a wide range of tools and machinery parts in the manufacturing industry due to its high hardness, toughness, and wear resistance. It is commonly used to produce molds, dies, cutting tools, and machine components. Its versatility makes it a popular choice among manufacturers.

Medical Industry

In the medical field, A9 tool steel is often used to make surgical instruments due to its high hardness and resistance to wear. Due to its biocompatibility with human tissue, it is also used to produce medical implants, such as hip replacements.

Construction Industry

The construction industry also relies on A9 tool steel for various applications, such as making heavy-duty equipment like cranes and bulldozers. Its toughness makes it suitable for construction tools like hammers, chisels, saw blades, etc., requiring frequent impact or heavy loads.

A9 Tool Steel Corrosion Resistance

Tool Steel A9 has good corrosion resistance due to its high chromium content, which helps prevent rusting and pitting. However, it should be noted that the alloy does not have full stainless steel-like corrosion resistance since it does not contain molybdenum or nickel, which are essential for stainless steel corrosion resistance.

A9 Tool Steel Heat Resistance

Tool Steel A9 has excellent heat resistance due to its high chromium content, which helps protect the alloy from oxidation at high temperatures. The alloy can be used at temperatures up to 1250°F (675°C) without any significant loss in strength or hardness.

A9 Tool Steel Heat Treatment

Tool Steel A9 can be hardened by heat treatment processes such as quenching and tempering. Quenching involves heating the alloy until austenite forms, followed by rapid cooling in oil or water to form martensite, which gives the alloy its strength and hardness properties. Tempering involves reheating the quenched material at lower temperatures in order to reduce brittleness while maintaining strength and hardness properties.

A9 Tool Steel Machining

Tool Steel A9 can be machined with conventional methods such as turning, drilling and milling, but it should be noted that it does require more power than softer steels such as mild steel or aluminium alloys due to their higher hardness level. High-speed steel (HSS) tools are recommended when machining this tool steel because they can better withstand the higher cutting forces required when machining harder materials like Tool Steel A9. The material should also be cooled with lubricants during machining operations to reduce friction between the cutting tool and workpiece, which will help improve tool life and surface finish quality on the finished part.


Tool Steel A9 is a versatile material with many uses ranging from cutting tools such as knives and punches to forming tools like heading dies and extrusion mandrels due to its good wear resistance combined with excellent heat treatment properties, machinability and corrosion resistance. In addition, it has good toughness making it suitable for use in applications where impact loading may occur. With proper care during fabrication, this type of tool steel can provide reliable performance for many years. With all these features, Tool Steel A9 is an ideal choice for many different types of tooling applications.

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