Steel Standard Comparison, CNS, JIS, AISI, ASTM, DIN

The key to precise metal processing is knowing the characteristics of alloy steel or other material. Before commencing mass production of any OEM/ODM metal part, the Tien-I team focuses on understanding the customer's need. We make the recommendation for alloy steel after considering cost efficiency of alloy steel processing.

That's why the international standards for alloy steel form the foundation of this business. We provide a general introduction below.

1. Chinese National Standard (CNS)

Coding of steel material for Chinese National Standard (CNS) is mainly based on CNS 109 G1001 (published March 1947; edited March 1996).

In principle, this is composed of three parts.

(1) The first part refers to the material. Stainless material is usually signified by S (Steel) or F (Ferrum).

(2) The second part comprises two elements:

a) Standard name or product use. Common usage: P = Plate; T = Tube; U = Use; W = Wire; F = Forging; C = Casting. Example: S P CC denotes plate, steel plate (cold); SUP denotes Use Spring, Spring Steel.

b) Stainless material used for structure (including structural carbon steel or alloy steel) mainly represented as alloy element or carbon content (structural carbon steel). When indicating carbon content, figures usually represent 100 multiple of carbon content. Example: SCM42 = Cr-Mo steel, 420 type; S25C = carbon steel, carbon content 0.25%

(3) The third part denotes type number—the lowest resistance strength or yield strength for that material, usually shown as a three-digit number. For example: SCM 420 means material of type number 420 for CR-MO steel.

2. Japanese Industrial Standard (JIS)

Japanese Industrial Standard (JIS) is mainly divided into two types for the steel material number:

(1) General Mechanical structure carbon steel. The material number is the same as with CNS. Example: S30C means carbon content 0.30% of mechanical structure carbon steel.

(2) Other use of carbon steel and alloy steel. This kind of material code divided into three parts.

a) The first part denotes material. Example: S = steel; F = iron means F. For other non-steel materials, please refer to Table 11.

b) The second part denotes steel specification or use. Example: K = tool steel; TB = boiler pipe; PC2 = cold-rolled steel.

c) The third part denotes type of steel material, represented as 1; 2; 3. When needed, the material processing method (eg. heat treatment) is added at the end. Example: D = Drawing; G = Grinding; T = Turning; Ex = Extruded. Usually, heat treatment is notated after the metal symbol or inserted between two items.

Example: SK2 = Second type of Carbon Tool Steel; SKS11 = 11th type of cutting tool steel; SUH301 = 301st type of heat-resistant steel; SUS301-1/2H = 301st type of stainless steel, 1/2 hard material.

3. American Iron and Steel Institute - The Society of Automotive Engineers (AISI-SAE)

In 1941, the American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE) established a classification of steel material. Types are represented as four- or five-digit numbers.

(1) The first digit denotes the type of steel. Example: 2 = nickel steel;  7 = tungsten steel.

(2) The second digit denotes the main alloy percentile. (When no other alloy element is present, this is signified by 0.)

(3) The third and fourth digits refers to the carbon content.

Example: SAE1045 = carbon steel, carbon content 0.45 (same as CNS S45C); SAE4140 = CR-MO steel, carbon content 0.40 (same as JIS SCM440).

4. American Society for Testing and Materials / American Society of Mechanical Engineers ASTM (ASME)

ASTM is a very widely used material specification, and its characters focus primarily on product feature and performance. ATSM notation is formulated as letter + symbol, followed by year. ASME uses many ASTM specifications

Example: ASTM A36-77a = (Steel) (Structural use) (1977) (first edit). In addition: ASTM E8 means tensile test specification .

5. Deutsches Institut fur Normung e.V (DIN)

Historically, DIN stood for Deutsch Industrienorm (German industry norm); today it stands for Deutsches Institut für Normung. The Chinese Steel specification falls under DIN 17006 (additional information is found in DIN 17007). In 1974, this was revised by the International Organization for Standardization in Euronorm 27-74. Classification is formed of letters and digits. The letters specify the type of steel, smelting method, alloy materials, processing condition; the digits specify steel material, carbon content, tensile strength, and main alloy's element fixed-point number.

a) 1st part: carbon content

b) 2nd part: alloy element type

c) 3rd part: alloy element content

(1) Carbon steel is generally notated as carbon element and its carbon content. Example: C60 = 0.6% carbon steel content. Figures also denote tensile strength. Example: St50 = structural carbon steel, tensile strength 50kg/mm2; CK40 = carbon steel with low content phosphorus and sulfur, tensile strength 40kg/mm2.

(2) Superior steel and low alloy steel mainly use alloy element and content as notation. In order not to use a decimal point, the value is already multiplied by a fixed-point number and shown as an integer, so when calculating the actual amount, it must be divided by the fixed-point number.

Example: Carbon content 0.34% chromium content 1% steel, show as 34Cr4. Therefore, 13CrV53 means carbon content 0.13%, chromium content 5/4=1.25%, vanadium content 3/10=0.3%.

(3) High-alloy steel. If X is added at the front of the notation, since the alloy element content is high, it will be directly represented instead of multiplied. (As previously stated, high-alloy steel usually denotes material with over 8% alloy content.)

Example: Stainless steel with carbon content 0.12% stainless steel, chromium content 18%, nickel content 8% is shown as X12CrNi18-8. Similarly, X10CrNi1810 means high alloy steel with carbon content 0.10% high alloy steel, chromium 18%, nickel 10. If its qualities require further notation, letters can be added at the beginning or at the end of the notation to denote smelting method, product features,performance category, heat treatment, and so on. 

(4) Cast iron. G denotes general cast iron, and other letters are added to indicate its type. The rest of the notation is the same as with steel. Example: GS-C30 = cast steel, carbon content 0.30% G-X120Mn12 means carbon content 1.20% cast iron, manganese content 12%.