AMPCO® Aluminum Bronze Grades: How to Choose the Right One

If you have already identified aluminum bronze as the right material family for your application, the next decision is which grade. The AMPCO® product line covers a structured range of aluminum bronze alloys, each engineered for a specific combination of strength, hardness, wear resistance, corrosion behavior, and process compatibility.

This guide breaks down the AMPCO® aluminum bronze range by application type and provides a decision framework for narrowing in on the right grade.

The AMPCO® aluminum bronze
range at a glance

AMPCO® aluminum bronze grades fall broadly into four families:

Each grade is detailed below with its profile, typical applications, and the standards it meets.

General-purpose grades

• AMPCO® 8
  The corrosion-and-erosion specialist. AMPCO® 8 balances hardness with ductility, delivering strong resistance to corrosion, erosion, abrasion, and cavitation pitting. Typical applications include pipes, tubes, joints, marine and process components, and bolting. Approved for food-contact applications.

• AMPCO® 18
  The most widely specified grade for general-purpose mechanical components. A compact grain structure produced by hot working during extrusion gives AMPCO® 18 a balanced property profile, making it the default choice for bushings, bearings, gears, worm wheels, valve seats, pump rods, and gibs. Also used for pipes, tubes, and joints in process and marine industries. Approved for food-contact applications.

Heat-treated high-strength grades

• AMPCO® 18.22
  A heat-treated grade that increases tensile strength, yield strength, and hardness over AMPCO® 18 while retaining good ductility. This balance of strength and flexibility suits aerospace components that must withstand high impacts and loads, including thrust bearings and bearing liners, bushings and inserts, piston parts, sliders, guides, and spindle nuts. Like the other grades in this family, it runs against stainless steel without galling and carries no risk of nickel contamination.
  
  

• AMPCO® 18.23
  A heat-treated upgrade with substantially higher physical properties than AMPCO® 18, including tensile strength, hardness, and wear resistance, combined with strong toughness and resistance to distortion under impact. The remarkable proportional limit allows designers to take full advantage of its strength. Engineered for heavy-duty worm gears and similar high-stress applications.
  

• AMPCO® 18.136
  A specialty heat-treated grade in which impact strength is increased by 40% and elastic limit in compression by 10% versus AMPCO® 18, with tensile strength preserved. Designed specifically for steel mill applications such as slipper pads and screw-down nuts that combine extreme wear pressure with significant impact loading.

Hard alloys for forming and wear

These grades are characterized by elevated aluminum and iron content, producing the hard gamma 2 phase (approximately 400 HB Brinell) distributed throughout the microstructure. They excel in metal forming, drawing, and applications where stainless steel must be shaped without nickel contamination, galling, or seizing.

• AMPCO® 21
  High wear resistance from uniformly distributed hard gamma 2 phase. Typical applications: guide bushings, die rings, inserts, forming rolls, and centerless grinding work-rest blades , particularly for machining stainless steel where galling, seizing, and scratching are concerns.
  
  

• AMPCO® 22
  A duplex-structure alloy (approximately 50% gamma 2 phase and 50% beta phase) offering unsurpassed hardness, compressive strength, wear resistance, and sliding properties. Specifically suited to stainless steel forming and drawing where tight tolerances must be held over long production runs.
  

• AMPCO® 25
  A patented extreme-hardness alloy with excellent compressive strength and frictional properties. The reference grade for deep drawing dies, forming rolls, and high-compression wear applications.
  

• AMPCO® 26
  A patented hard alloy engineered for stainless steel drawing dies and high-stress forming rolls. Combines exceptional hardness with wear resistance and durability under high pressure.

Premium high-performance grades

• AMPCO® 45
  A high-strength alloy whose mechanical properties exceed those of conventional nickel-aluminum bronzes. Compliant with AMS 4640 and ASTM B 150 for extrusions and AMS 4880 for castings. Resistant to abrasive wear, friction, deformation, and chemical erosion. Used in aircraft bearings and bushings, pump and marine shafts, wear rings, valve spindles and seats, and non-sparking safety tools for potentially explosive atmospheres.
  

• AMPCO® M4
  The reference choice for aircraft landing gear bearings and bushings. Increased aluminum and iron content produces uniformly distributed hard gamma 2 phase, delivering excellent wear resistance, reduced friction, and high mechanical strength. Compliant with AMS 4590 for extrusions and AMS 4881 for casting. Also specified for tube bending mandrels, gears, and wear and guide plates. A beryllium-free alternative that avoids the industrial hygiene requirements of beryllium copper. Approved for food-contact applications.

How to choose: a decision framework

Working through these four questions will narrow your choice to one or two candidate grades.

What is the primary loading mode?

• High static or impact load , heat-treated grades (AMPCO® 18.23, AMPCO® 18.136)
• High compressive load with friction , AMPCO® 25, AMPCO® 26
• Sliding and wear load , AMPCO® 18, AMPCO® 21, AMPCO® 22, AMPCO® M4
• Fluctuating loads in corrosive media , AMPCO® 8, AMPCO® 18

What is the operating environment?

• Seawater and process fluids , AMPCO® 8, AMPCO® 18
• Elevated temperatures (up to roughly 400 °C) , AMPCO® M4, AMPCO® 45
• Explosive atmospheres (non-sparking required) , AMPCO® 45
• Food-contact , AMPCO® 8, AMPCO® 18, AMPCO® 22, AMPCO® M4
  

What material are you working with or against?

• Stainless steel forming or drawing , AMPCO® 21, AMPCO® 22, AMPCO® 25, AMPCO® 26
• Carbon steel sliding contact , AMPCO® 18, AMPCO® M4
• Soft metals or non-metallic contact , AMPCO® 8, AMPCO® 18
  

Is the part subject to a specific industry standard?

• Aerospace structures: AMPCO® 45 (AMS 4640 and ASTM B 150 for extrusions, AMS 4880 for castings), AMPCO® M4 (AMS 4590 for extrusions, AMS 4881 for castings)
• Food contact , AMPCO® 8, AMPCO® 18, AMPCO® 22, AMPCO® M4
  

Worked examples

Example 1: Steel mill slipper pad

• Loading: high impact combined with sliding wear. Environment: hot, abrasive, lubricated. Standards: none specific.

• Recommendation: AMPCO® 18.136. Heat treatment delivers the 40% impact strength uplift the application demands, and the grade is engineered for exactly this duty cycle.

Example 2: Stainless steel deep-drawing die

• Loading: very high compressive load. Material contact: 304 or 316 stainless steel sheet. Tolerance: tight, must hold over long production runs.

• Recommendation: AMPCO® 25 (or AMPCO® 22 for forming where ductility is also valued). Both control the galling and tolerance drift that plague tool steels in this application.

AMPCO setup for deep drawing stainless steel pots

Example 3: Aircraft landing gear bushing

• Loading: high cyclic, with shock loading at touchdown. Environment: elevated temperature, demanding fatigue conditions. Standards: AMS 4590 required (Extruded).

• Recommendation: AMPCO® M4. The reference material for this application. AMPCO® M4 is qualified to AMS 4590 for extrusions and AMS 4881 for castings; for an extruded bushing, AMS 4590 applies.

Example 4: Seawater pump impeller

• Loading: moderate, continuous. Environment: full seawater immersion with cavitation risk.

• Recommendation: AMPCO® 8 (or AMPCO® 18 if bushings and seats are integral). AMPCO® 8 is engineered specifically for resistance to corrosion, erosion, abrasion, and cavitation pitting.

When the standard range needs
to be adjusted

For projects with unusual requirements , extreme service conditions, specific dimensional needs, or compliance with a customer specification not covered by the standard range , AMPCO METAL also offers custom chemical compositions on request.

Where AMPCO® aluminum bronze differs
from generic aluminum bronze

The grade is only one piece of the equation. The way an aluminum bronze is melted, cast, and worked has a major impact on its real-world performance , and this is where the AMPCO® product line distinguishes itself from generic aluminum bronze.

The next post in this series, Why AMPCO® Aluminum Bronze Outperforms Standard Aluminum Bronze: The MICROCAST® Advantage, explains how AMPCO METAL's production process drives the property advantage.

Next steps

If you have narrowed the choice to a few grades and want to validate the selection, AMPCO METAL's engineering team can review your application requirements, recommend the optimal grade and form, and provide certified technical data sheets