GB/T 1222-2016Spring Steels

Foreword

The Standard is drafted according to the rules given in GB/T 1.1-2009 The Standard replaces GB/T 1222-2007 “Spring steels”. Compared with GB/T 1222-2007, the main technical changes of this Standard are as follows:

steels are extended to 120 mm. The thickness of spring flat steels is extended to 60 mm. The diameter of the spring steel wire rods is extended to 40 mm (see Clause 1);

- ADD terms and definitions (see Clause 3);

56Si2MnCr, 60CrMnMo, 52CrMnMoV, 60Si2MnCrV, 52Si2CrMnNi, and their relevant technical requirements. Among them, 40SiMnVBE is the patented grade (see 6.1.1, 6.4, Annex B and Annex C);

- ADJUST the composition range of some steel grades, and ADD the requirements for phosphorus content and sulphur content (see Table 1);

- ADD the requirements for oxygen content for alloy spring steels (see 6.1.2);

- TIGHTEN the qualification level of macro defects (see 6.6.2 of this Standard,

- GROUPE the qualification level of nonmetallic inclusions, and ADD the requirement for the DS type inclusion (see 6.7 of this Standard, 5.7 of 2007 edition);

- ADD two cross-section shapes, i.e. plane great circle spring flat steel and plane rectangular spring flat steel, and their dimension requirements; CANCEL the cross-section shape of single-sided double-groove spring flat steel and its relevant requirements (see Annex A);

- ADD the main usage of different steel grades and the comparison table of national and international steel grades (see Annex B and Annex C).

This Standard was proposed by China Iron and Steel Industry Association This Standard shall be under the jurisdiction of National Technical Committee on Steel of Standardization Administration of China (SAC/TC 183).

Main drafting organizations of this Standard: Jiangyin Xingcheng Special Steel Works Co., Ltd., China Metallurgical Information and Standardization Institute, Fangda Special Steel Science and Technology Co., Ltd., Henan Productivity Promotion Center, Jiangsu Yonggang Group Co., Ltd., Beijing Jiaotong University, Xining Special Steel Co., Ltd., Dye Special Steel Co., Ltd.

Main drafters of this Standard: Wu Ming, Yao Tiehua, Zhou Junyi, Luan Yan, Dai Qiang, Chen Ming, Chang Linchao, Hui Weijun, Han Jianzhong, Chen Lie, Du Xianfeng.

The previous released versions replaced by this Standard are as follows:

Introduction

The issuing authority of this document draws attention to the fact that, when the statement complies with this document, the relevant contents of Table 1, 6.1.2, Table 3, Table 4, D.2 and E.2 of this document relate to the use of 40SiMnVBE patented steel.

The issuing authority of this document takes no stand on the authenticity, validity and scope of patents.

The patent holder has assured the issuing authority of this document that he is willing to negotiate with any applicant on a reasonable and non-discriminatory terms and conditions regarding licensing of patents. The patent holder’s statement has been filed with the issuing authority of this document. Related information can be obtained by the following way:

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing authority of this document shall not be held responsible for identifying any or all such patent rights.

1 Scope

The Standard specifies the terms and definitions, order contents, dimension, shape, weight, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of hot-rolled, forged and cold-drawn spring steels.

The Standard is applicable to spring round steels and spring square steels with a nominal diameter or a side length of not more than 120 mm (hereinafter referred to as bars), spring flat steels with a nominal width of not more than 160 mm and a nominal thickness of not more than 60 mm, spring steel wire rods with a nominal diameter of not more than 40 mm.

The grades and chemical composition specified in this Standard are also applicable to steel ingots, billets and their products.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

Steel with elastic property and is used for manufacturing springs and elastic components.

within the specified range, the elastic deformation capability enables the steel to withstand a certain load, and no permanent deformation occurs after the load is removed.

4 Order contents

The order contract or order based on this Standard shall include following contents:

c) Steel grade or unified digital code;

e) Dimension and accuracy (see Clause 5);

f) Delivery condition or code (see 6.3);

g) Hardenability requirement (if required, see 6.5);

h) Nonmetallic inclusion group (see 6.7);

i) Decarburization layer group (see 6.8);

j) Special requirements (if required, see 6.10).

5 Dimension, shape and weight

6 Technical requirements

6.2 Smelting method

Unless otherwise specified in the contract, the smelting method is chosen by the manufacturing plant.

6.3 Delivery condition

The steel may be delivered according the to the pressure processing method, heat treatment method, and surface roughness listed in Table 1. The specific delivery condition shall be indicated in the contract. For example: hot-rolled stress-relief-annealed spring steel (code: WHR+A); hot-rolled softeningannealed spring steel with level 1 surface roughness (code: WHR+SA+FB).

6.5 End hardenability

6.5.1 55SiMnVB and 28SiMnB steel shall be subjected to the end hardenability test. The minimum Rockwell hardness value at 9 mm from the quenching end shall comply with the specification of Table 5. If the supply party can assure that the hardenability is qualified, this inspection may be exempted.

6.5.2 As required by the demand party and indicated in the contract, the end hardenability of other spring steels (excluding 55SiMnVB and 28SiMnB) may also be determined by the end hardenability test method or the DI value calculation method specified in Annex A of GB/T 5216-2014. The ordering method of hardenability band shall be implemented according to 6.6 of GB/T 5216-2014, and the specific requirement shall be indicated in the contract.

6.6 Low power

a It is only applicable to continuous casting steels. As required by the demand party, the wire rod may be evaluated according to YB/T 4413, and the qualification level is agreed upon between the c The recommended heat treatment system for 70Mn is: normalizing 790 °C, the allowable adjustment range is d See Annex D for the typical mechanical property parameters. […]

7 Test methods

8 Inspection rules

8.1 Checking and acceptance

8.1. […]

8.2 Batching rules

The steel products shall be checked and accepted in batches. Each batch consists of steel products of the same steel grade, the same furnace number, the same dimension, the same delivery condition, and the same heat treatment furnace (or system).

8.3 Sampling quantity and sampling positions

The sampling quantity and sampling positions of each batch of steel products shall comply with the specifications of Table 10.

9 Packaging, marking and quality certificate

9.2 Agreed upon between the supply and demand parties and indicated in the contract, it may also use other special packaging, marking and protection measures.

Annex A Cross-section shape, nominal

A.1.1 Cross-section shape of hot-rolled flat steels

According to the cross-section shape, hot-rolled flat steels are divided into plane semicircle flat steel (see Figure A.1), plane great circle flat steel (see Figure A.2), plane rectangle flat steel (see Figure A.3). The specific crosssection shape shall be indicated in the contract. If not indicated, it shall supply according to Figure A.1. […]

A.1.4 Length and tolerance of hot-rolled flat steels

A.1.4.1 The normal length of hot-rolled flat steels is 30000 mm ~ 6000 mm; the short size of not less than 2000 mm may also be delivered but its weight shall not be more than 10 % of the total delivery weight. Agreed upon between the supply and demand parties, it may supply flat steels with a length of more than 6000 mm.

indicated in the contract and the tolerance is +50

A.2 Shape and tolerance of hot-rolled flat steels

A.2.1 Hot-rolled flat steels shall be free from the lateral bending and flat bending which affects the usage. The curvature per meter shall comply with the specifications of Table A.5. The specific group shall be indicated in the contract. If not indicated, regard it as Group 2.

Annex B Main features and usage of each steel grade

The main usage of each steel grade in this Standard is shown in Table B.1. The usage is very wide, while it is normally used for small size springs with low operating temperature, or unimportant big size springs and general mechanical springs It is used to manufacture different kinds of small cross-section flat springs, coil springs, clockwork springs, etc. It may also be used to manufacture ring springs, valve springs, absorbers, clutch springs, brake springs, etc. 28SiMnB It is used to manufacture automobile leaf-springs 40SiMnVBE It is used to manufacture heavy truck, mid-sized automobile and compact car leaf springs. It may also be used to manufacture leaf springs and spiral springs of mid- sized section. 55SiMnVB 38Si2 It is used to manufacture elastic strips used on the track fastening The usage is wide, while it is normally used to manufacture various springs such as leaf springs of automobile, haulage motor and tractor, spiral springs, automobile stabilizer bars with general requirements, truck bogie springs with low stress, and elastic strips used on the track fastening 55CrMn It is used to manufacture automobile stabilizer bars; it may also be used to manufacture big-size leaf springs and spiral springs 60CrMn 60CrMnB It is suitable to be used to manufacture of thick plate springs, automobile leading arms, etc. 60CrMnMo It is used to manufacture ultra-large springs used in large scale civil construction, heavy vehicle, machinery, etc. 60Si2Cr It is used to manufacture important springs, engineering machinery springs, etc. […]

Annex C Comparison table of steel grades in this Standard and steel grades in national

The comparison table of steel grades in this Standard and steel grades in national and international standards is shown in Table C.1 No. A Key: A - Steel grades in this Standard.

Annex D Main technical parameters of 28SiMnB and 40SiMnVBE steels

D.1 Main parameters of 28SiMnB steel

D.2 Main parameters of 40SiMnVBE steel

The mechanical property reference values of 40SiMnVBE steel with different dimensions and under different heat treatment conditions are shown in Table D.4.

Annex E End hardenability band of some steel grades

Bibliography