LT – B3 hot rolled steel billet for skew rolling mill

LT – B3 hot rolled round steel technical agreement

grinding steel ball bar

grinding steel ball bar


The provisions of this standard: The size, shape, weight and allowable deviation, technical requirements, test method, inspection rules, packing,

mark and quality certificate of grinding steel ball billet.

This standard applies the diameter and thickness ∮65-110mm hot rolled round steel.

Quoted standard

GB/T222 Style sampling method for steel chemical composition analysis of the chemical components and finished products allow deviation

GB/T226 Steel macrostructure and defect of acid corrosion test method

GB/T702 Hot rolled round steel and square steel size, shape, quality and allowable deviation

GB/T1979 Macrostructure defect is just the rating figure

GB/T2101 Sections of the acceptance certificate, packing, marking and quality general provisions

GB/T4336 Carbon steel and low alloy steel photoelectric emission spectrum analysis method

ASTM E45 The determination method of non-metallic inclusion content in steel

GB/T13299 The steel microstructure evaluation methods

GB/T17505 General technical conditions of delivery of steel and steel products

GB/T3077 structural alloy steel

Size, Shape, Weight

-3.1The size, shape, weight and allowable deviation of hot rolled round steel should match stipulation of GB/T702 the second group.

-3.2 Steel scale 6 meter,

Technical requirements

4.1Grades and chemical component

4.1.1 The grades and chemical component of steel should match the stipulation of table 1

Table 1 Steel chemical component(The percentage of weight %)



4.1.2 The chemical component allowable deviation of round steel(billet) is executed according to GB/T222 table 2

4.2 Smelting process electric furnace/converter+Outdoor vacuum refining to gas

4.3Delivery condition

Delivery at hot rolled condition, cold hole process, the compression ratio of steel billet≥14

4.4 macro

4.4.1 The cross section of steel pickling macrostructure specimens can’t have visual visible contraction cavity, bubble, flaw, entrainment,skull patch,fish eye,intercrystalline crack

4.4.2 The qualified level of pickling macrostructure should match stipulation of table 2

Table 2

center porosity(Grade)General porosity(Grade)Ingot shape segregation(Grade)


4.5 nonmetallic inclusion

Round steel should inspect according to ASTM E45, Its qualified grade should match the stipulation of table 3 parameter requirement.

Table 3

Thin deparmentThich departmentThin deparmentThich departmentThin deparmentThich departmentThin deparmentThich department


4.6 metallographic structure

Hot rolled state organizations are not allowed to bainite or martensite exists.

4.7 Products of billet required compression ratio shall not be less than 14

4.8 Hot upsetting qualified

4.9 Surface quality: According to GB/T3077-1999 Article 6.6.1 to execute, Sampling pickling ensure

experimental method

Each batch of steel test method should be executed according to table 4

Table 4

S.N.Inspection itemSample numberSampling locationExperimental method
1Chemical component1GB/T222GB/T223、GB/T4336
2Macro2Different billet or steelGB/T226、GB/T1979
3nonmetallic inclusion2Different billet or steelASTM E45
4metallographic structure1Any steel rodGB/T13299
5SizeOne by oneAny steel rodcallipers、micrometer
6Surface qualityOne by oneWhole steel rodvisual
7Hot upsetting2Different steel rodGB/T233


6、Inspection stipulation

6.1 check and accept

6.1.1 Steel factory inspection and acceptance conducted by the supplier quality and technical supervision department

6.1.2 The supplier must ensure that delivery of steel in accordance with this agreement or contract

6.2 Organization Rule

Steel should be according to the number of inspection and acceptance, Each batch should be composed of the same grade, the same furnace number,

the same processing method, the same size, the same delivery condition, the same heat treatment system(melt)

6.3 Sample quantity and sampling location.

The sample quantity and sampling location of each batch steel should accord with the stipulation of table 4.

6.4 The reinspection decision rules

6.4.1 The reinspection decision rules of steel is executed according to GB/T17505

Packing, Mark and quality certificate.

The packing, mark and quality certificate of steel should accord with the stipulation of GB/T2101


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