Raw Material Purchase Technical Requirements of High Strength Anchor Bolt Products

1 SCOPE

This technical requirements specifies dimensions, shape, weight, tolerances, technical requirements, test methods, inspection regulations, packaging, marking and supplier quality assuance, of the hot-rolled round bars – LT anchor bolt products’ raw materials.

This technical requirements apply to Φ20mm~ 80mm hot-rolled round bars.

2 NORMATIVE REFERENCES

The folowing standards contain provisions which,through reference in this text, constitute provisions of this technical requirements. For dated references, all subsequent amendments(not including errata content) or revisions, do not apply to this standard,  and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.For undated references, the latest edition of the normative document referred to applies.

GB/T 222-2006    Permissible tolerances for chemical composition of steelproducts 钢的成品化学成分允许偏差

GB/T 223         Methods for chemical analysis of iron,steel and alloy钢铁及合金化学分析方法

GB/T 224-2008    Determination of depth of decarburization of steels 钢的脱碳层深度测定方法     

GB/T 226-1991    Test method for macrostructure and defect pf steel by etching钢的低倍组织及缺陷酸蚀检验法

GB/T 228.1-2010  Metallic materials Part 1: Method of test at room temperature 金属材料室温拉伸试验方法

GB/T 229-2007    Metallic materials-Charpy pendulum impact test method 金属夏比缺口冲击试验方法

GB/T 231.1-2009  Metallic materials-Brinell hardness test-Part 1: Test method 金属布氏硬度试验 第1部分：试验方法

GB/T 702-2008    热轧圆钢和方钢尺寸、外形、重量及允许偏差Hot-rolled steel bars-Dimensions,shape,weight and tolerances

GB/T 1979-2001   Standard diagrams for macrostructure and defect of structural steels 结构钢低倍组织缺陷评级图

GB/T 2101-2008   General requirement of acceptance, packaging, marking, and certification for section steel 型钢验收、包装、标志及质量证明书的一般规定

GB/T 2975-1998   Steel and steel products-Location and preparation of test pieces for menchanical testing 钢及钢产品力学性能试验取样位置和试样制备

GB/T 3077-2015   Alloy structure steels合金结构钢

GB/T 6394-2002   Metal-methods for estimating the average grain size 金属平均晶粒度测定法

GB/T 10561-2005  Steel-Determination of content of nonmetallic inclusions 钢中非金属夹杂物显微评定法

GB/T 13299-1991  Steel-Determination of microstructure 钢的显微组织评定法

GB/T 17505-1998  Steel and steel products-General technical delivery requirements 钢及钢产品交货一般技术条件

GB/T 20066-2006  Steel amd iron-Sampling and preparation of samples for the determination of chemical composition钢和铁 化学成分测定用试样的取样和制样方法

3 HOT-ROLLED STEEL ROUND BARS-DIMENSIONS,SHAPE,WEIGHT AND TOLERANCES

3.1 Tolerance on length shall be 0～+50mm

3.2 Tolerance on size shall be 0~+0.6mm

3.3 The permissible ovality for all diameters of round bars, measured as the difference between the maximum and minimum diamters of the same cross section, shall be ≤0.4mm

3.4 The straightness tolerance shall be ≤2mm/m, shall be less than 0.2% of the total bar length

3.5 Other dimensions, shape, weight and tolerances that are not specified here, shall compliance with relevant regulations of GB/T 702.

4 TECHNICAL REQUIREMENTS

4.1.1 Grades and chemical composition

Steel grade and chemical composition(heat analysis)shall be as specified in table 1

             TABLE 1  chemical composition(heat analysis,wt%)

4.1.2 Permissible tolerances for chemical composition of steel round bars according to GB/T 222

4.2 Smelting process

 Converter/Elevtric Furnace+LF+VOD+Continuous Casting

4.3 Delivery Condition

Hot-rolled

4.4 Mechanical Properties

    Mechanical properties according to GB/T3077-2015, table 3 regulations for 35CrMo and 42CrMo.

4.5 MACROSTRUCTURE

After etching specimens for macrostructure, its surface shall not have visible residual holes, bubbles, cracks, inclusions, skull patch, white spot, axi-cored intergranular cracks(according to 6.6.1 of GB/T3077-2015).   

Macrostructure etching according to table 4 in GB/T3077-2015 regulations: General looseness,center looseness, ingot segregation shall not more than 2.0 grade. General point segregation and edge point segregation are not allowed(according to GB/T3077-2015 regulations-Grade A(Advanced high performance steel).

4.6 ULTRASONIC DETECTION 

Manufacturer shall take ultrasonic detection to 100% steel round bars according to GB/T4162-2008.Round bars which satisfy grade A,should company with supplier quality assurance with clear statement.   

4.7 DECARBURIZED LAYER 

Hot-rolled round bar complete decarburization depth (ferrite+transition layer)shall not more than 1.5% nominal diameter of round bar. (accodging to GB/T3077-2015-6.9 regulations)

4.8 NONMETALLIC INCLUSION 

    According to GB/T 10561 determination, nonmetallic inclusion of steel round bars shall  qualify as table 2 regulations. 

                                                    TABLE 2 

4.9  GRAIN SIZE 

   Test austenite grain size of steel round bars according to GB/T 6394, qualified number ≥6  

4.10 SURFACE 

    Surface of hot-rolled steel round bars shall not have visible crack, Scab, folding or inclusions. In case of any above defects， clearing depth according to GB/T 3077-2015-table 6 regulations.  

5 TEST METHOD 

Steel specimens taking and test method shall according to table 3 regulations. 

TABLE3 sampling and test method

6 TEST AND ACCEPTANCE INSPECTION 

6.1 Supplier’s quality supervision department shall perform test and acceptance check. Supplier shall assure hot-rolled steel round bars in accordiance with this technique requirement. Purchaser have right to inspect every item in this technical requirements in random.

6.2 Round bars shall be test as per patch.Each batch shall be composed of the same grade,the same heat, the same production methods, the same dimension, the same delivery condition, the same heat treatment (heat).

6.3  Retests and determinations 

Retests and determinations of hot-rolled steel round bars shall be according to GB/T 17505 regulations.

7 PACKAGING, MARKING AND SUPPLIER QUALITY ASSURANCE 

7.1 Every delivery of steel round bars shall be accompanied by supplier quality assurance , to prove these products meet certain standard and purchase order requirements.  

7.2 Supplier quality assurance shall assure legibly note:

a) Supplier’s name or brand ；

b) Purchaser’s name；

c) Date of delivery；

d) Standard ；

e) Grade ；

f) Heat（batch）number,deliver condition，applications,weight,pieces;

g) commodity,dimension(modle) and grade；

h) standard and every test result in the contract；

i) Stamps of suppliers’quality supervision department

Except above regulations, steel packaging, marking, and supplier quality assurance shall be according to GB/T 2101 regulations.