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GB/T 34484 consists of two parts, under the general title Heat-treatable Steels:
— Part 1: Non-alloy Steels;
— Part 2: Alloy Steels for Quenching and Tempering.
This part is Part 2 of GB/T 34484.
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
This part has been redrafted and modified adoption of International Standard ISO 683-2:2016 Heat-treatable Steels, Alloy Steels and Free-cutting Steels — Part 2: Alloy Steels for Quenching and Tempering.
This part has been changed largely from ISO 683-2:2016 in terms of structure; a list of the clauses in this part and the equivalent clauses in the International Standard ISO 683-2:2016 is given in the informative Annex A.
There are technical deviations between this part and the International Standard ISO 683-2:2016, and such deviations have been marked by perpendicular single line (|) in the outer side page margin of the corresponding clauses. A complete list of technical deviations, together with their justifications, is given in Annex B.
For the purposes of this part, the following editorial changes have also been made:
— the standard name is changed from Heat-treatable Steels, Alloy Steels and Free-cutting Steels — Part 2: Alloy Steels for Quenching and Tempering to Heat-treatable Steels — Part 2: Alloy Steels for Quenching and Tempering;
— the informative Annex D and Bibliography in ISO 683-2:2016 are deleted;
This part was proposed by China Iron and Steel Industry Association.
This part is under the jurisdiction of National Technical Committee 183 on Iron and Steel of Standardization Administration of China (SAC/TC 183).
Heat-treatable Steels — Part 2: Alloy Steels for Quenching and Tempering
1 Scope
This part of GB/T 34484 specifies the ordering information, dimensions, shape, weight, technical requirements, test methods, inspection rules, packaging, marking and certification of alloy steels for quenching and tempering.
This part is applicable to rolled round steels with nominal diameter no more than 310 mm and rolled square steels with nominal side length no more than 280 mm (hereinafter referred to as steels).
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.
GB/T 222 Permissible Tolerances for Chemical Composition of Steel Products
GB/T 223.9 Iron, Steel and Alloy — Determination of Aluminium Content — Chrom Azurol S Photometric Method
GB/T 223.11 Iron, Steel and Alloy — Determination of Chromium Content — Visual Titration or Potentiometric Titration Method (GB/T 223.11-2008, ISO 4937:1986, MOD)
GB/T 223.13 Methods for Chemical Analysis of Iron, Steel and Alloy — The ammonium Ferrous Sulfate Titration Method for the Determination of Vanadium Content
GB/T 223.17 Methods for Chemical Analysis of Iron, Steel and Alloy — The Diantipyrylmethane Photometric Method for the Determination of Titanium Content
GB/T 223.23 Iron, Steel and Alloy — Determination of Nickel Content — The Dimethylglyoxime Spectrophotometric Method
GB/T 223.26 Iron, Steel and Alloy — Determination of Molybdenum Content — The Thiocyanate Spectrophotometric Method
GB/T 223.53 Methods for Chemical Analysis of Iron, Steel and Alloy — Flame Atomic Absorption Spectrometric Method for the Determination of Copper Content
GB/T 223.60 Methods for Chemical Analysis of Iron, Steel and Alloy — The Perchloric Acid Dehydration Gravimetric Method for the Determination of Silicon Content
GB/T 223.62 Methods for Chemical Analysis of Iron, Steel and Alloy — The Butyl Acetate Extraction Photometric Method for the Determination of Phosphorus Content
GB/T 223.64 Iron, Steel and Alloy — Determination of Manganese Content - Flame Atomic Absorption Spectrometric Method (GB/T 223.64-2008, ISO 10700:1994, IDT)
GB/T 223.69 Iron, Steel and Alloy — Determination of Carbon Contents — Gas-volumetric Method after Combustion in the Pipe Furnace
GB/T 223.72 Iron, Steel and Alloy — Determination of Sulfur Content — Gravimetric Method
GB/T 223.75 Iron, Steel and Alloy — Determination of Boron Content — Methanol Distillation-curcumin Photometric Method
GB/T 226 Test Method for Macrostructure and Defect of Steel by Etching
GB/T 228.1 Metallic Materials — Tensile Testing — Part 1: Method of Test at Room Temperature (GB/T 228.1-2010, ISO 6892-1:2009, MOD)
GB/T 229 Metallic Materials — Charpy Pendulum Impact Test Method (GB/T 229-2007, ISO 148-1:2006, MOD)
GB/T 230.1 Metallic Materials — Rockwell Hardness Test — Part 1: Test Method (GB/T 230.1-2018, ISO 6508-1:2016, MOD)
GB/T 231.1 Metallic Materials — Brinell Hardness Test — Part 1: Test Method (GB/T 231.1-2009, ISO 6506-1:2014, MOD)
GB/T 702-2017 Hot-rolled Steel Bars — Dimensions, Shape, Weight and Tolerances
GB/T 1979 Standard Diagrams for Macrostructure and Defect of Structural Steels
GB/T 2101 General Requirement of Acceptance, Packaging, Marking, and Certification for Section Steel
GB/T 4162 Forged and Rolled Steel Bars — Method for Ultrasonic Testing
GB/T 4336 Carbon and Low-alloy Steel — Determination of Multi-element Contents — Spark Discharge Atomic Emission Spectrometric Method (Routine Method)
GB/T 6394 Determination of Estimating the Average Grain Size of Metal
GB/T 10561-2005 Steel — Determination of Content of Nonmetallic Inclusions — Micrographic Method Using Standards Diagrams (ISO 4967:1998, IDT)
GB/T 17505 Steel and Steel Products — General Technical Delivery Requirements (GB/T 17505-2016, ISO 404:2013, MOD)
GB/T 20066 Steel and Iron — Sampling and Preparation of Samples for the Determination of Chemical Composition (GB/T 20066-2006, ISO 14284:1996, IDT)
GB/T 20123 Steel and Iron — Determination of Total Carbon and Sulfur Content Infrared Absorption Method after Combustion in an Induction Furnace (Routine Method)
3 Ordering Information
Contracts or orders made based on this part shall cover the following information:
a) the number of this part;
b) product name;
c) designation;
d) smelting method (see 5.2);
e) surface hardness (see 5.4);
f) grain size (see 5.7)
g) non-destructive tests (see 5.8);
h) remanence (see 5.9);
i) weight (or quantity);
j) dimensions and shape (see Clause 4);
k) special requirements.
4 Dimension, Shape and Weight
4.1 The dimensions and tolerances of steels shall comply with the requirements of GB/T 702-2006, Group 2.
4.2 The shape and tolerances of steels shall comply with the requirements of GB/T 702-2006, and the curvature shall comply with the requirements of Group 2.
4.3 The dimensions, shape and tolerances of steel bars in other dimensions shall comply with the requirements of corresponding standards. The specific requirements shall be indicated in the contract through negotiation between the supplier and the purchaser.
4.4 Deliver the steels according to actual weight.
5 Technical Requirements
5.1 Designation and chemical composition
5.1.1 The designation and chemical composition (smelting analysis) of steel shall comply with the values in Table 1.
Table 1 Designation and chemical composition
Table 1 (continued)
5.1.2 Allowable deviation of chemical composition of finished steel products shall comply with the requirements of GB/T 222.
5.2 Smelting process
Unless otherwise specified in contract, the smelting process shall be selected by the supplier.
5.3 Delivery condition
Steels shall be delivered in quenched and tempered condition. See Table 2 for the recommended heat treatment system for delivery.
Table 2 Recommended heat treatment system for steels
Table 2 (continued)
5.4 Mechanical properties
5.4.1 The longitudinal mechanical properties test results of steels treated according to the heat treatment system recommended in Table 2 shall comply with the requirements specified in Table 3.
5.4.2 As required by the purchaser and indicated in the contract through negotiation between the supplier and the purchaser, the range of surface hardness of steel can be specified. The surface hardness range of delivered steels shall not be less than 40 HBW or 5 HRC. Mechanical property test results are not required for steels delivered according to surface hardness.
Table 3 Mechanical properties
No. Designation Nominal diameter (d) or side length (t)
mm
20 ≤ d ≤ 40
10 ≤ t ≤ 20 40 < d ≤ 100
20 ≤ t ≤ 60 100 < d ≤ 160
60 ≤ t ≤ 100 160 < d ≤ 310
100 ≤ t ≤ 280
Specified plastic elongation strength
Rp0.2
MPa Tensile strength
Rm
MPa Elongation after fracture,
A
% Percentage reduction of area, Z% Impact energy absorptiona
KV2
J Specified plastic elongation strength
Rp0.2
MPa Tensile strength
Rm
MPa Elongation after fracture,
A
% Percentage reduction of sectional area, Z
% Impact energy absorptiona
KV2
J Specified plastic elongation
strength
Rp0.2
MPa Tensile strength
Rm
MPa Elongation after fracture,
A
% Percentage reduction of sectional area, Z
% Impact energy absorptiona
KV2
J Specified plastic elongation strength
Rp0.2
MPa Tensile
strength
Rm
MPa Elongation after fracture,
A
% Percentage reduction of sectional area Z
% Impact energy absorptiona
KV2
J
≥ ≥ ≥ ≥ ≥ ≥ ≥ ≥
1 35Cr, 35CrS 590 800 to 950 14 40 40 460 700 to 850 15 45 40 Measured Measured Measured Measured Measured Measured Measured Measured Measured Measured
2 40Cr and 40CrS 660 900 to 1100 12 35 35 560 800 to 950 14 40 35 Measured Measured Measured Measured Measured Measured Measured Measured Measured Measured
3 50CrVA 800 1000 to 1200 10 45 30 700 900 to 1100 12 50 30 650 850 to 1000 13 50 30 600 800 to 950 13 50 30
4 25CrMo, 25CrMoS 600 800 to 950 14 55 50 450 700 to 850 15 60 50 400 650 to 800 16 40 45 Measured Measured Measured Measured Measured
16 40MnB 850 1050 to 1250 12 50 40 800 1000 to 1200 12 50 40 Measured Measured Measured Measured Measured Measured Measured Measured Measured Measured
a Indicating the minimum of the average impact absorbed energy of three impact samples; the single value of one sample is permitted to be below the specified minimum, but not below the 70% of the specified minimum.
5.5 Macrostructure
5.5.1 The acid leached macrostructure test piece of steel cross section shall be free from visible defects such as shrinkage cavity, bubbles, cracks, inclusions, skull patches and white points.
5.5.2 The acceptable class of acid leached macrostructure of steels shall comply with the requirements specified in Table 4.
Table 4 Macrostructure defects and acceptable class
Pattern segregation Central segregationa Center porosity General porosity General spot segregationc Edge spot segregationd
Class ≤
2 2 2b 2 Not allowed
a Only for continuous casting billet rolled steels.
b For steels with a nominal size greater than 200 mm, the acceptable class shall not be greater than 2.5.
c 38CrMoAl steel shall not be greater than class 2.5.
d 38CrMoAl steel shall not be greater than class 1.5.
5.6 Nonmetallic inclusions
Nonmetallic inclusions shall be graded in accordance with GB/T 10561-2005, Method A, and the test result shall be in accordance with the acceptable classes specified in Table 4.
Foreword II
1 Scope
2 Normative References
3 Ordering Information
4 Dimension, Shape and Weight
5 Technical Requirements
5.1 Designation and chemical composition
5.2 Smelting process
5.3 Delivery condition
5.4 Mechanical properties
5.5 Macrostructure
5.6 Nonmetallic inclusions
5.7 Grain size
5.8 Ultrasonic testing
5.9 Remanence
5.10 Surface quality
6 Test Methods
7 Inspection Rules
7.1 Inspection and acceptance
7.2 Batching rules
7.3 Sampling quantity and sampling position
7.4 Reinspection and judgment rules
8 Packaging, Marking and Quality Certificate
Annex A (Informative) Structural Changes of This Part with Respect to ISO 683-2:
Annex B (Informative) Technical Deviations between This Part and ISO 683-2:2016 and Their Justifications
Annex C (Informative) Designation of Steels Given in This Part and of Comparable Grades Covered in Foreign Standards
Annex D (Normative) Sampling Location for Mechanical Property Test
