What do “CRES,” “CRSS” and “CRS” mean on a drawing?

You’ll often find CRES, CRSS or CRS in the material block or notes of a drawing, especially on older aerospace and military prints. CRES and CRSS tell you the part is made from stainless steel; CRS usually means carbon steel. None of them, on its own, tells you which alloy or temper the part needs.

What the abbreviations stand for

CRES — corrosion-resistant steel

CRES is a broad term. It can describe any stainless steel, from 300 series grades such as 301, 304 and 316 to 400 series grades such as 410 and 430, along with precipitation-hardening grades like 17-7PH®. Those alloys differ widely in strength, corrosion resistance, formability and magnetic properties, so “CRES” alone isn’t enough to choose one.

CRSS — cold rolled stainless steel

CRSS describes how the material was made, not what it is. Nearly all thin-gauge stainless strip is cold rolled, so CRSS adds little beyond “stainless.” It also doesn’t mean the material is hard: cold rolled stainless is supplied in every temper from Annealed to Full Hard.

CRS — cold rolled steel

CRS usually means cold rolled carbon steel, not stainless. Like CRSS, it describes how the material was made, so it doesn’t say which grade (for example 1008, 1010 or another carbon steel) or which temper. Cold rolled carbon steel strip comes in tempers from #1 (Hard) to #5 (Dead Soft) under ASTM A109, and the right one depends on how the part is formed.

Don't mix up CRS with CRES or CRSS. The letters are close, but the materials aren't. Carbon steel doesn't have the corrosion resistance of stainless and will rust without plating or coating, while stainless costs more and behaves differently in forming. If a drawing says CRS, the part most likely calls for a carbon steel such as 1008 / 1010 — confirm before you order.

Why we can’t choose the alloy for you

Picking an alloy and temper is an engineering decision. The right choice depends on how the part is formed, the strength it needs, the environment it works in and whether it is welded or heat treated. Only the design owner, usually your engineering department or your customer, can make that call. Guessing could mean the part fails in service or your material certifications don’t match what the drawing intended.

What to look for instead

Before you request a quote, check these places for the missing details:

• The drawing notes or material block. Many drawings list the abbreviation along with a grade or specification, such as “CRES 302,” “CRES per AMS 5516” or “CRS 1010, #5 temper.”
• Your purchase order or your customer’s purchase order. The governing specification is often listed there rather than on the drawing.
• The parts list or bill of materials.
• Your engineering department or the drawing’s design authority.

An AMS specification is the most complete answer, because each one covers a single alloy and temper. For example, AMS 5516 is 302 Annealed and AMS 5519 is 301 Full Hard. You can look up specifications in our Specification Cross Reference.

An ASTM specification alone isn’t enough. ASTM specs cover many alloys and tempers at once (ASTM A666, for example, covers a range of stainless grades from Annealed through Full Hard), so if your drawing calls out an ASTM spec, we still need the alloy and temper along with it. The same goes for CRS: ASTM A109 covers carbon steel strip in several tempers, so we need the grade and the temper.

Ready to request a quote?

Once you know the alloy and temper (or, for stainless, the AMS specification), add the thickness, width and quantity, and send it through our Request a Quote form or call (800) 992-5015. If you’re not sure what your drawing is calling for, send it along with your request and we’ll help you work out which questions to ask.

This article is educational information only. Always order to the alloy, temper and specification called for by your drawing or purchase order.