What is material condition?

Material condition states which heat treatment or cold work the stock has been through when it arrives. Together with composition and size, the condition sets strength, hardness, structure and residual stress, and with them how the material machines and whether a treatment is still needed after machining. For aluminium the condition, usually called the temper, follows the alloy, as in T6 or O; for steel it follows the grade with a plus sign, as in +N, +QT or +C.

What does the standard say about the material condition?

For aluminium, EN 515 defines the tempers: F as fabricated, O annealed, H strain hardened, W and T heat treated. T6 is solution heat treated and artificially aged; T651 adds stress relief by controlled stretching between solution treatment and ageing. For steel the condition symbols are in EN 10027-1, including +A soft annealed, +N normalised, +QT quenched and tempered, +C cold drawn and, for stainless steel, +AT solution annealed. Which conditions exist for a grade is stated in that grade's product standard.

How does the material condition work in practice?

The same steel grade in two conditions can lead to two routes. If the drawing asks for 42CrMo4 at quenched and tempered strength, you can buy +A, machine it more easily and have it quenched and tempered afterwards, with stock allowance, a subcontracted heat treatment and often a finishing operation. Or you buy +QT and machine straight to size, at lower cutting data and with no quenching and tempering afterwards. In aluminium, stretched material such as T651 usually moves less than unstretched material when machined from one side. If the condition is missing from the drawing, ask the customer before the route is settled.

What is the material condition often confused with?

Material condition is not the heat treatment you have carried out: the condition is how the stock arrives, a heat treatment is a step in your route. Nor is it hardness, which is a property that follows from the condition and may appear on the drawing as a requirement. Maximum material condition in geometrical tolerancing is unrelated to any treatment: it concerns size.

How do you see the material condition in Blake?

In Blake the material from the drawing, with its condition where the drawing gives one, sits with the part as a proposal; you confirm or correct it, and who did so and when stays visible. If the part still needs quenching and tempering or hardening after machining, you add that treatment as its own subcontract line in the estimate, priced from your own subcontract library; without a price the line stays open. More on materials.