# AZ91D magnesium

Selecting AZ91D by casting route, condition, test basis, corrosion protection and machining controls.

Reviewed: 2026-11-01

Tags: materials, magnesium, casting-alloys, specialty-metals

## Identity and purchase specification

The **2015 NADCA A-3-11** table gives **230 MPa tensile**, **160 MPa 0.2%-offset yield** and **3% elongation over 51 mm**, all **typical at 20°C** for **separately die-cast, as-cast AZ91D specimens**. The table excludes specimens removed from production castings. Establish how the actual housing section will be accepted. [NADCA 2015 alloy-data table](https://www.abdiecasting.com/wp-content/uploads/2017/08/Section-03-Alloy-Data.pdf)

**AZ91D** is a magnesium-aluminum-zinc alloy designation commonly associated with die casting. The International Magnesium Society's ingot-designation table maps AZ91D to **ISO-MgAl9Zn1(A)** and **ISO-MB21120**. Such a cross-reference identifies an alloy family; it does not certify a casting, establish producer provenance or supply every composition and property requirement. [IMS: magnesium ingot designations](https://www.imsmg.org/Designation/index.aspx)

Specify the governing material/product standard and edition, casting process, condition, drawing and required inspection documentation. For example, **SAE AMS4490K**, revised **30 May 2017**, explicitly concerns **die castings in AZ91D, Temper F, as cast**. Its published scope illustrates why form and condition belong in the specification; it is not evidence that this historical revision is the current edition required by a project. [SAE: AMS4490K](https://saemobilus.sae.org/standards/ams4490k-magnesium-alloy-castings-die-90al-070zn-az91d-temper-f-cast)

Do not substitute sand-cast AZ91 variants, wrought magnesium, powder or an additively manufactured part solely because a supplier uses “AZ91” in its description. Agree chemical limits, casting quality, mechanical requirements and any coating or repair restrictions for the actual ordered product.

## Bounded mechanical data

The **2015 NADCA Product Specification Standards**, Table **A-3-11**, presents these typical AZ91D values for **as-cast, separately die-cast specimens**, explicitly excluding specimens cut from production castings:

| Property | Typical value and stated basis |
| --- | --- |
| Ultimate tensile strength | 230 MPa at 20 °C |
| Yield strength | 160 MPa, 0.2% offset, at 20 °C |
| Elongation | 3% over 51 mm, at 20 °C |
| Young's modulus | 45 GPa at 20 °C |

Source: [NADCA 2015, alloy-data section hosted by A&B Die Casting](https://www.abdiecasting.com/wp-content/uploads/2017/08/Section-03-Alloy-Data.pdf).

These typical data do not guarantee every location in a casting. Specify acceptance specimens, sampling location, orientation and section thickness; a test bar cannot rule out local defects in a housing.

## Mass and stiffness need separate checks

Meridian's material chart lists AZ91D density as **1.81 g/cm³** and elastic modulus as **45 GPa**. The accessible chart does not state a complete test/conditioning protocol, so treat it as selection guidance rather than a contractual acceptance table. [Meridian: material-property comparison](https://www.meridian-mag.com/magnesium-die-casting/magnesium-faq/datasheet.pdf)

**Illustrative mass calculation:** a nominal net material volume of 100 cm³ at 1.81 g/cm³ gives **181 g**. This excludes coatings, fasteners and volume or density variation. It does not establish an interchangeable lightweight design: changing wall thickness, ribs, mounting points or material changes stiffness, buckling and stress distribution as well as mass. Reassess those requirements when redesigning an aluminum or steel part in magnesium.

## Corrosion and assembly design

NADCA attributes AZ91D corrosion performance to strict control of **iron, copper and nickel impurities**. Preserve the applicable limits and delivered analysis; “high purity” does not establish environmental immunity. [NADCA: magnesium-alloy selection](https://www.abdiecasting.com/wp-content/uploads/2017/08/Section-03-Alloy-Data.pdf)

For the assembled component, specify humidity, salt or process-fluid exposure, dissimilar-metal contacts, crevices and cleaning chemicals. Review fasteners, inserts, electrical contacts and coating damage as an assembly, and obtain a qualified corrosion-protection system for the intended duty. Require tests representative of the contact geometry and exposure rather than extending a bare-alloy chart to a coated, bolted housing.

Record appearance criteria separately from loss of function or strength. Check coating continuity at edges and machined features, drainage and water-trapping details, and how the assembly will be inspected or repaired. A coating designation alone does not establish the life of a complete component.

## Casting, heat exposure and alternative routes

Specify acceptance limits and inspection for porosity, cold shuts and other defects in critical features.

Room-temperature as-cast data do not establish elevated-temperature creep, long-term fastener retention or a permitted coating-bake cycle. Obtain condition-specific evidence for sustained heat exposure and confirm any post-casting thermal treatment with the foundry and applicable specification. This page supplies no general heat-treatment or remelting recipe.

Aconity3D's **09.20** AZ91D sheet illustrates the importance of route: it labels its mechanical data **“as built”** and says values depend on powder, process parameters and surrounding conditions. Those results are additive-process data, not replacements for die-cast specimen properties or proof of compliance with a casting specification. [Aconity3D: AZ91D process datasheet](https://aconity3d.com/documents/materials/Data%20Sheet_AZ91D_0920.pdf)

## Machining and material handling

Luxfer MEL Technologies' **Machining Magnesium, datasheet 254**, treats tooling, machine/workpiece rigidity, chip extraction and heat generation together. Its guidance emphasizes sharp tools and adequate chip clearance; cutting recommendations depend on operation and equipment. Do not transfer a published maximum cutting speed directly to an unqualified machine, casting geometry or coolant system. [Luxfer: machining magnesium](https://www.luxfermeltechnologies.com/wp-content/uploads/2026/03/Machining-Magnesium.pdf)

The International Magnesium Association's **Safe Handling of Magnesium, February 2020**, distinguishes solid material from molten metal and finely divided forms. It identifies chips, grinding residues and powder as readily ignitable, warns about airborne-dust explosion hazards, and calls for engineered collection and housekeeping. It also warns that water contact with molten magnesium is hazardous and that water must not be used on a magnesium fire. [IMA: safe handling guidance](https://cdn.ymaws.com/www.intlmag.org/resource/resmgr/safety/Safe-Handlling-of-Mg.pdf)

Use the exact supplier's current safety information and a facility procedure appropriate to the operation, including chip storage, coolant compatibility, dust collection and suitable fire response. A solid casting's normal handling behavior cannot establish the precautions for powder, accumulated swarf or melting. Avoid uncontrolled mixtures of chips, fluids and other shop waste.

## Purchase and acceptance record

Retain:

- Full alloy designation, product specification/edition, casting route and condition.
- Producer/heat traceability and required chemical-analysis documentation.
- Sampling basis for properties and limits for casting defects or permitted rework.
- Dimensional, fastening, sealing and surface-finish requirements.
- Coating system and relevant thermal, corrosion and component tests.
- Machining, chip-handling and inspection procedures.

The cited NADCA section is explicitly **2015**, SAE entry **May 2017**, IMA guide **February 2020**, and Aconity sheet **09.20**. Meridian's chart and Luxfer's accessible machining sheet do not establish clear technical revision dates; a URL upload directory is not an edition. Confirm current controlled documents for procurement and process qualification.

## Related reference

[Grades, tempers and conditions](../grades-tempers-and-conditions.md)