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GB/T 35840 consists of four parts under the general title Steels for plastic mould:
——Part 1: Non-alloy steels;
——Part 2: Pre-hardening steel bars;
——Part 3: Corrosion resistant steels;
——Part 4: Pre-hardening steel plates.
This is Part 1 of GB/T 35840.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part was proposed by the China Iron and Steel Association.
This part is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
Steels for plastic mould - Part 1: Non-alloy steels
1 Scope
This part of GB/T 35840 specifies the order contents, dimensions, shapes, weights, technical requirements, test methods, inspection rules, packaging, marking and certification of non-alloy steels for plastic mould.
It is applicable to hot-rolled or wrought non-alloy round steel, square steel, flat steel and steel plate (hereinafter referred to as steel) for manufacture of plastic moulds.
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 223.5 Steel and iron - Determination of acid-soluble silicon and total silicon content - Reduced molybdosilicate spectrophotometric method
GB/T 223.11 Iron, steel and alloy - Determination of chromium content - Visual titration or potentiometric titration method
GB/T 223.18 Methods for chemical analysis of iron, steel and alloy - The sodium thiosulfate separation iodimetric method for the determination of copper content
GB/T 223.23 Iron, steel and alloy - Determination of nickel content - The dimethylglyoxime spectrophotometric method
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 223.72 Iron steel and alloy - Determination of sulfur content - Gravimetric method
GB/T 223.86 Steel and iron - Determination of total carbon content - Infrared absorption method after combustion in an induction furnace
GB/T 226 Test method for macrostructure and defect of steel by etching
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method
GB/T 247 General rule of package, mark and certification for steel plates (sheets) and strips
GB/T 709 Dimension, shape, weight and tolerances for hot-rolled steel plates and sheets
GB/T 1299-2014 Tool and mould steels
GB/T 1979 Standard diagrams for macrostructure and defect of structural steels
GB/T 2101 General requirements of acceptance, packaging, marking, and certification for section steel
GB/T 2970-2016 Method for ultrasonic testing of thicker steel plates
GB/T 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing
GB/T 4336 Carbon and low-alloy steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (routine method)
GB/T 6402 Steel forgings- Method for ultrasonic testing
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 10561-2005 Steel - Determination of content of nonmetallic inclusions - Micrographic method using standards diagrams
GB/T 17505 Steel and steel products - General technical delivery requirements
GB/T 20066 Steel and iron - Sampling and preparation of samples for the determination of chemical composition
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 Order contents
The contract or order for the steel ordered according to this part shall include the following information:
a) a reference to this part;
b) product name;
c) designation (see 5.1);
d) smelting method (see 5.2);
e) product specification;
f) dimension and shape accuracy (see 4);
g) delivery state (see 5.3);
h) weight (or quantity);
i) special requirements.
4 Dimension, shape and weight
4.1 The dimension, shape and tolerance of round steel, square steel and flat steel shall be in accordance with those specified in 5.1 and 5.2 of GB/T 1299-2014.
4.2 The dimension, shape and tolerance of steel plate (sheet) shall be in accordance with GB/T 709.
4.3 Through agreement between the supplier and the purchaser and as indicated in the contract, steels of other dimension, shape, weight and tolerance may also be supplied.
4.4 The round steel, square steel and flat steel are generally delivered according to the actual weight. The steel plate (sheet) is generally delivered according to the theoretical weight, and the density shall be 7.85g/cm2 when calculating the theoretical weight.
5 Technical requirements
5.1 Designation and chemical composition
The designation and chemical composition of steel (finished product) shall be in accordance with those specified in Table 1.
Table 1 Designation and chemical composition of steel
S.N. Uniform numerical code Designation Chemical composition (mass fraction)/%
C Si Mn P S Cr Ni Cu
1 T10450 SM45 0.42~0.48 0.17~0.37 0.50~0.80 ≤0.025 ≤0.020 ≤0.20 ≤0.20 ≤0.25
2 T10500 SM50 0.47~0.53
3 T10550 SM55 0.52~0.58
Note 1: SM consists of the first capital letter of the Chinese Pinyin of “Su” and “Mu” in “Suliao Muju”.
Note 2: See Annex A for the comparison table of similar designations between this part and relevant national and international standards.
5.2 Smelting method
The steel shall be smelted by vacuum degassing or electroslag remelting, or by other smelting methods that meet the requirements of this part.
5.3 Delivery state
The steel is generally delivered in hot-rolled or hot-forging state.
5.4 Delivery hardness
The hardness of steel delivered in hot-rolled or forging state shall meet those specified in Table 2.
Table 2 Delivery hardness
Designation Brinell hardness HBW
SM45 155~215
SM50 165~225
SM55 170~230
5.5 Ultrasonic testing
5.5.1 Round steel, square steel and flat steel shall be subjected to the ultrasonic testing which shall be in accordance with those specified in GB/T 1299-2014, 6.10.
5.5.2 The steel plate (sheet) shall be subjected to ultrasonic testing. For steel plate (sheet) with a thickness up to 200mm, the qualification grade shall comply with the requirements of Grade II in GB/T 2970-2016; for steel plate (sheet) with a thickness greater than 200mm, the qualification grade shall be determined by the supplier and the purchaser through negotiation.
Foreword i
1 Scope
2 Normative references
3 Order contents
4 Dimension, shape and weight
5 Technical requirements
6 Test methods
7 Inspection rules
8 Packaging, marking and certification
Annex A (Informative) Comparison table of similar designations between this part and relevant national and international standards
