GB/T 13304.2-2008Steels classification -- Part 2: Classification of according to main quality classes and main property or application characteristics (English PDF)

5.1.2.2 in edition 1991);

-- Adjust the "sulphur or phosphorus content maximum" in definitions of

"common-quality non-alloy steel" and "common-quality low-alloy steel" from

0.045% to 0.040% (3.1.1.1c) and 4.1.1.1c) in edition 1991; 4.1.1.2c) and

5.1.1.2c) in this edition);

Steels Classification - Part 2. Classification of according to

Main Quality Classes and Main Property or Application

Characteristics

4.1 Classification according to main quality class

Non-alloy steels are classified according to the main quality class as follows.

4.2.1 The main property or application characteristic stated in this Part refer to the

characteristics considered in priority under some conditions like in formulation system

or steel classification.

4.2.2 The classification of non-alloy steels listed in Table 1 according to main property

or application characteristic is as follows.

A) Non-alloy steel with principal characteristic of required strength (or hardness)

maximum, e.g., sheet steel for cold forming;

B) Non-alloy steel with principal characteristic of required strength minimum, e.g.

structural steels for ship, pressure vessel and tube/pipe;

C) Non-alloy steel with major characteristic of required carbon content (except

steels specified in item d and e below), e.g. wire rod and quenched and

tempered steels;

D) Unalloyed free cutting steel with sulfur content minimum and smelting assay

value not less than 0.070% and (or) added with elements like Pb, Bi, Te, Se, Sn,

Ca or P;

E) Non-alloy tool steel;

F) Non-alloy steel with specially required magnetic property or electric property, e.g.

electromagnetic pure iron;

G) Other non-alloy steels, e.g. pure iron for raw material.

5.1 Classification according to main quality class

The main quality class of low-alloy steel is divided into.

A) Common-quality low-alloy steel;

B) Good-quality low-alloy steel;

C) Special-quality low-alloy steel.

(see 6.2).

6.1 Classification according to main quality class

The main quality class of alloy-steel is divided into.

A) Good-quality alloy-steel (see 6.1.1);

B) Special-quality alloy-steel (see 6.1.2).

6.1.1 Good-quality alloy-steel

6.1.1.1 Brief

Good-quality alloy-steel refers to the steel that the quality and property (like grain

fineness number or formability) shall be specially controlled in the manufacturing

process. But the production control of such steel is not stricter than the one for

special-quality alloy-steel.

6.1.1.2 Definition

Good-quality alloy-steels are as follows.

A) Alloy-steel for general engineering structures, like alloy-steel for steel sheet pile

(Q420bz in GB/T 20933) and alloy-steel for mine (all designations, except

20Mn2A , 20MnV and 25MnV, in GB/T 10560);

B) Alloy concrete steel, like alloy-steel in GB/T 20065;

C) Electrical alloy-steel, mainly containing silicon or silicon/ aluminum, not required

in magnetic permeability;

D) Alloy-steel for rail, like 30CuCr in GB 11264;

E) Steel for rock and exploratory drilling, like alloy-steel in GB/T 1301;

F) Wear-resistant steel with sulphur/phosphorus content higher than 0.035%, like

high manganese cast steel in GB/T 5680.

6.1.2 Special-quality alloy-steel

6.1.2.1 Brief

Special-quality alloy-steel refers to the steel that the chemical component and specific

manufacturing/ technological conditions shall be controlled strictly, to ensure the

overall performance improved within the required limit.

6.1.2.2 Definition

Alloy steels, expect good-quality alloy-steel defined in 6.1.1.2, are special-quality

alloy-steels.

6.1.2.3 General classification and example of special-quality alloy-steel

The general classification and example of special-quality alloy-steel is detailed in

column 2~8 in Table 3.

6.2 Classification according to main property and application characteristic

6.2.1 The brief for main property or application characteristic of non-alloy steel

stated in 4.2.1 is also applicable to alloy-steel.

6.2.2 The classification of alloy-steel (Table 3) according to main property or

application characteristic is as follows.

A) Alloy-steels for engineering structures, including alloy-steel for general

engineering structures, alloy-steels for hot-rolled or cold-rolled product (for cold

forming) (steels for pressure vessel, automobile and delivery line), pre-stressing

alloy-steel, alloy-steel for mine, high manganese wear-resistant steel, etc.;

B) Alloy-steels for mechanical structure, including quenched and tempered alloy

constructional steel, surface-hardening alloy constructional steel, alloy

constructional steel for cold shaping (upsetting and cold extruding), alloy spring

steel, except stainless, corrosion-resisting, heat resisting steels and bearing

steel;

C) Stainless, corrosion-resisting and heat resisting steels, including corrosion

resisting steel, acid-proof steel, oxidation resisting steel and refractory steel,

which microstructure comes with Martensite shaped steel, ferrite shaped steel,

austenite shaped steel, austenite-ferrite shaped steel, precipitation hardening

shaped steel, etc.;

D) Tool steels, including alloy tool steel and rapid tool steel. alloy tool steel comes

with steel for measurin...

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