5083 aluminum plate hardness

When sourcing 5083 aluminum plate for cryogenic tanks—whether for LNG, liquid oxygen, or liquid nitrogen storage—one of the first metrics you will check is 5083 aluminum plate hardness. But a single number on a data sheet tells only part of the story. What truly matters is how that hardness relates to strength, toughness, and weldability at extreme low temperatures. This guide gives you a clear, practical overview of hardness values across different tempers, how they compare with other alloys, and which temper best suits your cryogenic application.

Core Hardness Values for 5083 Aluminum Plate

5083 is a non‑heat‑treatable Al‑Mg alloy. Its hardness and strength come from cold working and subsequent stabilisation, not from heat treatment. The Brinell hardness (HB) ranges vary notably by temper, as measured per ASTM E10 (500 kgf load, 10 mm steel ball):

> Hardness testing is performed on the original mill surface and does not involve any surface treatment or secondary processing—it is a material‑inherent property.

What Hardness Tells You – and What It Doesn't

Higher hardness generally indicates higher tensile and yield strength. For instance, the O temper (~75 HB) delivers a tensile strength of about 275–350 MPa, while H321 (~90 HB) reaches 305–385 MPa.

However, for cryogenic tanks, the most critical property is impact toughness at low temperatures. Extensive testing shows that 5083 retains excellent Charpy impact values at -196°C (liquid nitrogen temperature) and does not exhibit a ductile‑to‑brittle transition. In fact, some tempers even show improved fracture toughness as the temperature drops. Therefore, hardness serves as a quick screening tool, but your final selection must be based on a combination of strength, low‑temperature toughness, and weldability—not hardness alone.

Which Temper Should You Choose?

Different parts of a cryogenic tank demand different material states. Here are practical recommendations:

- Tank shells and inner liners (direct contact with cryogenic media) → Choose 5083‑O or H111. These tempers have the lowest hardness (~70‑80 HB) but offer the best low‑temperature toughness and reliable weld performance—they are the industry standard for these critical components.

- External supports and structures in marine environments → Consider 5083‑H321. Its higher hardness (85‑95 HB) provides greater strength, and the stabilised condition gives excellent resistance to stress‑corrosion cracking. However, its formability is more limited than O‑temper.

- If extensive cold bending or forming is required → Always select the O temper, because lower hardness means better ductility and a lower risk of cracking during fabrication.

In short, the “best” hardness depends on your specific fabrication and service conditions.

How 5083 Compares with 5052 and Other Materials

Many engineers compare 5083 with 5052—both are 5xxx series alloys, but 5083 contains more magnesium (4.0‑4.9% vs. ~2.5% in 5052), giving it significantly higher hardness and strength. The Brinell hardness of 5083‑O is roughly 70 HB, whereas 5052‑O stands at about 47 HB. That difference explains why cryogenic pressure vessel codes (such as ASME SB209) consistently specify 5083 over 5052.

When compared with 304 stainless steel (which has a much higher hardness of 150‑200 HB), 5083 is about one‑third the density, offering substantial weight savings while maintaining excellent toughness at cryogenic temperatures—a clear advantage for large‑scale tank construction.

Essential Standards and Testing Requirements

For cryogenic‑service 5083 plate, always verify that the material complies with the following specifications and request a full Mill Test Report (MTR):

- ASTM B209 – General specification for aluminium sheet and plate

- ASME SB209 – Specific to pressure‑vessel and cryogenic applications

- ASTM E10 – Brinell hardness test method

- Additional requirements often include ‑196°C Charpy V‑notch impact tests and wide plate tensile tests to confirm low‑temperature performance.

Make sure that the acceptance hardness values are clearly stated in your purchase contract, along with the sampling and testing protocol.

Practical Guidance for Material Selection

The Brinell hardness of 5083 aluminium plate ranges roughly from 65 to 95 HB, depending on the temper. For most cryogenic tank projects, O‑temper and H111 (around 70‑80 HB) are the preferred options—they trade higher hardness for superior toughness at -196°C and reliable welding behaviour. Remember that 5083 aluminum plate hardness is a useful quality‑control parameter, but a truly sound material decision must also account for low‑temperature impact resistance, fracture toughness, and fabrication requirements.

For LNG, liquid hydrogen, or liquid oxygen tank projects that demand consistent quality and full standard compliance, Mingtai Aluminum supplies 5083 plate in a wide range of thicknesses and sizes, complete with comprehensive documentation to support your engineering needs.

FAQ 

Q1: What is the Brinell hardness range for 5083 aluminium plate?  

A: It ranges from about 65 to 95 HB, depending on the temper.

Q2: Which 5083 temper is most commonly used for cryogenic tanks?  

A: O‑temper or H111 are the standard choices because they offer the best low‑temperature toughness.

Q3: Which standard governs hardness testing for 5083?  

A: ASTM E10, using a 500 kgf load and a 10 mm ball indenter.

Q4: Is 5083 harder than 5052?  

A: Yes, 5083 is significantly harder—about 70 HB vs. 47 HB for 5052‑O.

Q5: Does 5083 become brittle at cryogenic temperatures?  

A: No, it retains good toughness at -196°C and shows no ductile‑to‑brittle transition.