Aerospace Plate and Sheet: Thresholds, Tempers, Tolerances and Blanks

Updated October 13, 2026

Where sheet ends and plate begins

For aluminum the break is 0.250 inch. The Aluminum Association's terms guide defines plate as a rolled product of rectangular section not less than 0.250 inch thick with sheared or sawn edges, and sheet as the same kind of product thinner than 0.250 inch but greater than 0.006 inch, with slit, sheared or sawn edges. Below that is foil, with a small overlap that is supplied to sheet specifications.

Tooling plate deserves a warning. The same guide describes it as cast or rolled product with internal stress controlled for machining stability in tool and jig applications. It is a different product from plate bought to an AMS material spec, so it should not stand in for spec plate on flight or deliverable hardware without engineering approval.

Titanium and stainless steel use their own thickness breaks, set in their product specifications such as ASTM B265 for titanium and ASTM A480 for stainless flat products. Check the break in the spec you are buying to, because a part drawn as sheet in one metal may be plate in another.

Tempers and stress relief: T651, T7351 and T7451

Heat-treatable aluminum plate is quenched after solution treatment, and the quench locks stress into the plate. The 51 in tempers like T651, T7351 and T7451 means the plate was then stretched to relieve that stress. The Aluminum Association guide defines stretching as applying a unidirectional force to impart permanent set, reducing internal stress and distortion.

• T651 is solution treated, stretched and aged to peak strength, the usual condition for 6061 and 7075 plate.
• T7351 is the stretched, overaged 7075 plate condition chosen for stress corrosion resistance.
• T7451 is the stretched 7050 plate condition bought to AMS 4050, used for thick machined structure.

What stretching does not do is make thick plate stress free. Stress is reduced, not removed, and deep pockets still move. Two buying consequences follow. First, never accept the unstretched temper for a heavily machined part because it was in stock; a 7075-T6 sheet cert does not cover a T651 plate application. Second, do not re-solution treat machined plate unless the drawing and the heat treat spec require it, since the stretch is lost and the part will distort. The aluminum alloys page covers stress corrosion ratings by temper, and the heat treatment reference covers what a processor needs on the PO.

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The specifications that govern plate and sheet

Aerospace aluminum flat products are bought to an AMS detail spec for each alloy and temper, or to the AMS-QQ-A-250 general specification and its alloy slash sheets. The table shows the status we found on SAE's site.

Material cert content and the 6061 slash sheet history are covered on our certified material page. The practical rule for flat stock is that one AMS number often covers both a sheet temper and a plate temper, so the cert must show the temper that matches the thickness you received.

Thickness and flatness tolerances

For aluminum, thickness, width, length, squareness and flatness tolerances come from ANSI H35.2 unless the material spec or your drawing sets tighter limits. The allowed values depend on alloy, thickness and width, so give the supplier the full size and let it apply the table rather than assuming one number for every plate.

• Thickness drives stock allowance. Buy plate thick enough that both faces clean up at the worst case of the thickness tolerance, plus whatever the shop needs to face off distortion after roughing.
• Flatness is measured on a baseplate. The Aluminum Association guide defines longitudinal bow as deviation from straightness measured with the product lying on a baseplate so its own weight minimizes the curvature. A plate that rocks on a surface plate may still be within tolerance by that method.
• Cut pieces inherit tolerance from the parent plate. A small blank cut from a large plate can carry more bow per inch than the full plate suggests, because tolerances are written for the mill size.
• Sheet for forming. Thickness variation affects bend allowance and springback. For formed parts our sheet metal fabrication service covers how shops handle it.

If the part needs a flatness or thickness better than the mill table, put it on the drawing as a machining requirement rather than a material requirement. Precision ground or machined plate is a different product with its own lead time.

Grain direction and short transverse properties

Rolled plate has three test directions, and strength and resistance to stress corrosion are not the same in each. The Aluminum Association guide defines them: longitudinal is the direction of rolling, long transverse runs across the width, and short transverse runs through the thickness.

Three things to put in the request when grain direction matters. Mark the grain direction on the drawing. Ask the cutter to mark the rolling direction on every blank, because once a square blank leaves the saw nobody can tell which way it was rolled. And when a part has lugs or press fits loaded through the thickness, ask your stress engineer whether the plate spec's reported properties include the short transverse direction or only L and LT, since thicker plate is where the difference shows.

Saw cut, waterjet and other blanks

The cutting method changes the edge you receive, not the material spec, so choose it by what happens to the edge next. Our technical cutting reference covers the methods in depth; for buying blanks the short version is:

For fatigue-critical or flight parts, the drawing or process spec usually requires thermally cut or waterjet edges to be machined back. Say so in the request, and size the blank with that allowance. Large blanks bound for big machines are covered on our large part machining page.

Mill certs for flat stock

A plate or sheet cert must tie the piece you hold to the mill lot, show the temper that matches its thickness, and carry any inspection the spec or PO requires. Beyond the general cert checks on our certs and traceability page, flat stock adds a few:

• Thickness range on the cert covers the actual thickness delivered, since minimum properties change with thickness
• Ultrasonic inspection stated when the spec or PO requires it for thick plate, with the document and class
• Clad or bare stated for alloys sold both ways, such as 2024
• Lot and heat numbers transferred to every cut blank, with the rolling direction marked
• Protective film, paper interleaving or surface condition noted when appearance or anodize quality matters

Ordering checklist for plate and sheet

• Alloy, temper and specification with revision, for example 7075-T7351 plate to AMS 4078
• Thickness, width and length, with tolerance basis (ANSI H35.2, AMS 2242 or drawing)
• Cutting method and edge requirement: saw, waterjet, shear, or edges machined back
• Grain direction on the drawing and rolling direction marked on every blank
• Ultrasonic procedure and class for thick plate when required
• Mill cert for the delivered lot and the cutter's C of C
• Country of melt and DFARS clause for titanium and stainless plate on defense contracts; see DFARS specialty metals
• Surface protection and packaging that keeps sheet flat and unscratched; see crating and packaging

Counterfeit and quality risks, and how to receive plate

The usual problems are temper substitution, sheet-temper certs supplied with plate, unmarked blanks and certs from a different lot. Check temper with conductivity and hardness on 7xxx plate, because T6, T651 and T7351 look the same. Measure thickness at several points and check bow on a surface plate by the same method the tolerance uses. Reject blanks with no marking or no rolling direction when the drawing calls grain. See our receiving inspection guide and the counterfeit avoidance process for sources outside the mill channel.

How we source plate and sheet

We do not hold plate or sheet, run saws or publish prices. We source flat stock for your order from mills, service centers and distributors with lot traceability, or from certified surplus when the paperwork fully supports it, flow down the spec, temper, tolerance, cutting and grain requirements, and check the certs against the blanks before they ship.

Blanks can go straight to the machine shop or fabricator on the same purchase order as the part, through our CNC machining route. Related stock is on the raw material category, including bar and rod, extrusions and tubing.

Request plate and sheet

Send the alloy, temper, specification, blank sizes, quantities, cutting method and any grain or ultrasonic requirement through the certified material request form. Blank sizes with grain direction let us check whether a remnant or a cut from standard plate will work before quoting a full plate. A person replies within one business day, and rush requests are prioritized.

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Part, quantity and date are enough to start. Drawings and the mutual NDA follow by reply, and controlled programs never send technical data through this site.

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Related

• Aerospace Bar and Rod: Specs, Finish, Tolerances and Inspection
• Aerospace Aluminum Extrusions: Profiles, Specs, Dies and Lots
• Buying Certified Aerospace Material and Surplus Drops
• Aerospace Sheet Metal Fabrication and Welded Assemblies

Sources

• Aluminum Association GAG Guidance Document 001: Terms and Definitions
• Aluminum Association product definitions (dues reporting instructions)
• SAE AMS-QQ-A-250: Aluminum and Aluminum Alloy, Plate and Sheet, General Specification
• SAE AMS 4045: Aluminum Alloy Sheet and Plate, 7075-T6 Sheet, T651 Plate
• SAE AMS 4078: Aluminum Alloy Sheet and Plate, 7075-T73 Sheet, T7351 Plate
• SAE AMS 4050: Aluminum Alloy Plate, 7050-T7451
• SAE AMS 4027: Aluminum Alloy Sheet and Plate, 6061-T6 Sheet, T651 Plate
• SAE AMS 4911: Titanium Alloy Sheet, Strip and Plate, 6Al-4V, Annealed
• SAE AMS 2242: Tolerances, Stainless Steel Sheet and Strip
• ANSI H35.2 overview (aluminum mill product tolerances)