Magnesium Zinc Alloy

AZ91 Magnesium Alloy: The Ultimate FAQ Guide

Before die casting AZ91 magnesium alloy, read this guide.

It has all information you have been looking for about AZ91 magnesium alloy.

Take a look.

What Is AZ91 Magnesium Alloy?

This refers to a material among the magnesium alloy, popularly used in die-casting, and is known for its excellent properties when it comes to strength, cast-ability, and corrosion resistance.

Plastic forming is one of the methods employed to improve the mechanical properties of the AZ91 magnesium alloy.

Magnesium alloy

Magnesium alloy

Where Is AZ91 Magnesium Alloy Used?

The AZ91 magnesium alloy is used in the die-casting process.

Also, the process involves making a mold cavity from molten metal under very high pressure.

The magnesium alloy is useful in several ways.

This includes; Housing, covers, sporting tools, computer parts, household equipment, handheld tools, mobiles & telephones, etc.

How Is AZ91 Magnesium Alloy Tested?

Testing of the AZ91 material is done through the Indentation process.

The process involves testing both the α-Mg matrix and eutectic β-Mg17Al12 phase.

It is carried out at elevated and room temperature and mechanical properties of both phases are observed.

What Elements Are Used In AZ91 Magnesium Alloy?

To improve the physical properties of the lightweight AZ91 magnesium alloy, it is mixed with other metal elements.

These elements constitute Aluminium, Zinc, Manganese, Copper, Silicon, Zirconium, and rare earth metals.

What Is The Specific Strength Of AZ91 Magnesium Alloy?

The strength of the alloy is summed up by a composition of tensile and yield strengths.

The tensile strength is quite high amounting to 199 MPa whereas the yield strength is slightly lower at 135 MPa.

How Is The Chemical Composition Of AZ91 Magnesium Alloy?

The AZ91 magnesium alloy has a chemical composition of Aluminium, Zinc, and Manganese.

Each is quantified as 9.0%, 0.8%, and 0.25% respectively as used in the current work systems.

How Are The Microstructure And Mechanical Properties For AZ91 Magnesium Alloy?

Magnesium die cast part

Magnesium die cast part

The structure of AZ91 is made up of an α-phase where precipitation of aluminum-rich β-phase

(Mg17Al12) takes place constantly with the grain boundaries.

The size of grains is said to be about 150 μm and the SZ is typically brought about by recrystallization of the grains.

Recrystallization of the grains does not tamper with the density, therefore, it is maintained at a constant value.

Below is a table exhibiting the mechanical properties of the AZ91 magnesium alloy.

Properties                          Metric                  Imperial

Tensile strength                240-250 MPa     35-36 ksi

Yield strength                    160 MPa              23.20 ksi

Elastic modulus                 45 GPa                 6526 ksi

Elongation                         3-7 %                    3-7 %

Hardness                            63                          63

What Is The Cost For AZ91 Magnesium Alloy?

Prices for the alloy may vary for different manufacturers.

The rough estimation for pricing is 9 dollars or more per piece.

Which Characteristics Do AZ91 Magnesium Alloy Have?

They have excellent mechanical properties

  • They are corrosion-resistant
  • Exceptional cast-ability properties
  • Strong and durable.
  • They are eco-friendly
  • They are lightweight.

How Much Magnesium Would You Find In AZ91?

About 90% of the total composition of the AZ91 alloy is made up of magnesium.

It is preceded by aluminum which ranges from 8.3-9.7%.

Then the rest of the metal constituents cover the remaining percentage which differs from one another.

This implies that only traces of these elements are present.

These metals comprise Manganese, Zinc, Silicon, copper, Iron, Nickel, and other earth metals.

The content in percentage is 0.15- 0.50, 0.35- 1, 0.1, 0.03, 0.005, 0.002, and 0.02 respectively.

Can You Die Cast AZ91 Magnesium Alloy?

Yes, die-casting of the AZ91 alloy is possible.

The metal alloy has excellent properties that make the process a success.

Here, a mold cavity is generated from a metal that is in a molten state with the effect of very high pressure and temperature.

The process is done in four different steps as follows

First, you are required to prepare the mold.

This is done by applying a lubricant on the inner walls of the mold so that temperature can be regulated.

The lubricant also creates a film between the mold and the molten metal thereby making cast removal easier and faster.

The second step involves the injection of the die mold with molten metal.

After preparation, the complete mold is closed and sealed in preparation for the highly pressurized molten metal.

The limit for pressure ranges from 1500 to 25000 pounds.

This varies depending on the application.

It is therefore maintained at a constant by the mold until the molten metal cools and solidifies.

Next, we have solid cavity ejection which happens to be the third step.

The resulting cavity from the previous step is hereby ejected from the mold aided by the ejector pins found on the mold.

Lastly, your fourth and final step involves the shakeout of existing scrap metals from the resulting cavity.

This comprises the metal traces stuck inside the mold since some molten metals do not form the casting.

To avoid the mold from being reused, the scrap metal is therefore removed.

What Are The Cons And Pros For AZ91 Magnesium Alloy?

The AZ91 magnesium alloy has more pros outweighing the number of cons, one of the reasons behind its popularity.

Magnesium AZ91 pros include;

  • The alloy is lightweight and therefore easy to work with.
  • Magnificent when it comes to cast-ability.
  • The strength to weight ratio is usually high.
  • Machining of the alloy can be done with ease.
  • The alloy is resistant to corrosion.
  • The alloy is cost-friendly.
  • Exceptional stiffness to weight ratio.
  • Easy disposal since they are eco-friendly.

Cons of the AZ91 are as follows;

They are highly prone to brittleness

Formability is only possible under high pressure and not at room temperature.

Is AZ91 Magnesium Alloy Corrosion Resistant?

Yes, the alloy is resistant to corrosion.

This resistance is brought about by strictly enforcing limits to the metal impurities.

These are Copper, Iron, and Nickel, there is use is minimized making Magnesium the key element in production.

Is AZ91 Magnesium Alloy Environmentally Friendly?

Environmental preservation concerns have been voiced progressively by the WHO.

Any product or manufacturing process has an environmental impact on the environment.

For this reason, coming up with an environmentally friendly perspective should be considered.

Among the magnesium alloys, AZ91 has the lowest environmental impact.

This, therefore, qualifies it as an eco-friendly alloy.

For any questions or inquiry about AZ91 magnesium alloy, contact us now.

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