Steel Warehouse has been a trusted supplier of carbon steel grades for more than 75 years, serving the industries that build and move the world. We offer a complete range of materials, from high strength and abrasion resistant grades to cold rolled strip, floor plate, and PVQ, processed to meet your exact requirements. Whether you need formability, durability, or lightweight strength, our team helps match the right grade to your production goals. With the experience, inventory, and technical support to back every order, we deliver steel that performs exactly as your application demands.
What Is a Steel Grade
A steel grade refers to a classification that defines the specific chemical composition and mechanical properties of steel, which are essential for determining its suitability for various applications. Each steel grade is designated by a unique identifier that often includes elements such as carbon content, alloying materials like chromium or nickel, and specific heat treatment processes that influence characteristics like strength, ductility, and corrosion resistance. For instance, a grade might specify whether it is carbon steel or alloy steel; each type serves distinct purposes based on its inherent qualities.
Unified Numbering System
The Unified Numbering System was developed by SAE and ASTM to classify steel grades using a 4-digit series of numbers. The first two digits specify the type of steel, and the second two digits specify the percentage of carbon in the grade.
First Two Digits:
10xx Plain carbon steel – no alloys
11xx Free-machining steels (S. Mn, P)
13xx Intermediate Mn steels
15xx High Mn steels
4xxx Molybdenum steels
5xxx Chromium steels
6xxx Chromium-vanadium steels
8xxx Triple alloy (Ni, Cr, Mo)
92xx Silicon-manganese steels
Second Two Digits:
Example:
1010 is 0.08% – 0.13%
1018 is 0.15% – 0.20%
Exceptions:
1008 is 0.10% max C
1006 is 0.08% max C
Why Choose Steel Warehouse
Trusted by industry leaders worldwide for reliable steel solutions and unmatched service excellence
16 Locations
Family-owned & Operated
75+ Years of Experience
Technical Experts
16 Locations
Strategically positioned to support your production wherever you operate.
Family-owned & Operated
A legacy of trust, built on quality and service.
75+ Years of Experience
Where generations of steel knowledge meet modern capabilities.
Technical Experts
Hands-on support from people who know your process.
