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Technical requirement for sets of torshear type high strength bolt hexagon nut and plain washer for steel structures
This standard is applicable to GB 3632-83 Type and dimension for sets of torshear type high strength bolt hexagon nut and plain washer for steel structures.
1 Technical requirements
1.1 Materials
Materials and property grades of bolts, nuts and washers shall meet the requirements of Table 1.
Table 1
Category Property grade Recommended material Material standard No.
Bolt 10.9S 20MnTiB GB 3077-82
Nut 10S 35# GB 699-65
15MnVB GB 3077-82
Washer Hardness 45# GB 699-65
1.2 Mechanical properties
1.2.1 Mechanical properties of bolt raw materials
The manufacturer shall conduct tensile test on raw materials, and make standard specimens after heat treatment. The mechanical properties shall meet the requirements in Table 2. According to the requirements of users, the impact toughness test of materials at room temperature may be carried out, and the results shall also meet the requirements of Table 2.
Table 2
Tensile strength σb Yield strength σ0.2 Elongation Shrinkage rate Impact value αk
N/mm2 (kgf/mm2) N/mm2 (kgf/mm2) δ5% Ψ% J/cm2 (kgf?m/cm2)
Minimum Maximum Minimum Maximum Minimum Minimum Minimum Minimum Minimum Minimum
1,040 1,240 106 126 940 95 10 42 59 6
1.2.2 Mechanical properties of bolts
The mechanical properties of bolts shall meet the requirements of Table 3.
Table 3
Property grade Mechanical properties σb Hardness Minimum tempering temperature shall meet the requirements of GB 3098.1-82, Table 2
N/mm2 (kgf/mm2) Rockwell HRC Vickers HV0.3
Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum
10.9S 1,040 1240 106 126 33 39 312 367
1.2.3 The tensile load of bolts shall meet the requirements of Table 4.
Table 4
Bolt diameter
d
mm Pitch
p
mm Nominal stress section area
As
mm2 Property grade 10.9S
Tensile load (As×σb)N Tensile load (As×σb)(kgf)
Minimum Maximum Minimum Maximum
16 2 157 163,000 195,000 16,600 19,800
20 2.5 245 255,000 304,000 26,000 31,000
22 2.5 303 315,000 376,000 32,100 38,300
24 3 353 367,000 438,000 37,400 44,600
1.2.4 Mechanical properties of nuts
The mechanical properties of nuts shall meet the requirements of Table 5.
Table 5
Property grade Proof stress Hardness
Sp N/mm2 Sp (kgf/mm2) Rockwell HRB Rockwell HRC Vickers HV0.3
Minimum Minimum Minimum Maximum Minimum Maximum
10S 1,040 106 98 28 221 274
1.2.5 The proof load of nuts shall meet the requirements of Table 6.
Table 6
Bolt diameter
d
mm Pitch
p
mm Nominal stress section area
As
mm Property grade 10S
Minimum proof load (As×Sp) N Minimum proof load (As×Sp)(kgf)
16 2 157 163,000 16,600
20 2.5 245 255,000 26,000
22 2.5 303 315,000 32,100
24 3 353 367,000 37,400
1.2.6 Mechanical properties of washers
Mechanical properties of washers are based on hardness values. The hardness values include Vickers hardness and Rockwell hardness. Vickers hardness HV 329 to 436 and Rockwell hardness HRC 35 to 45.
1.3 The decarburized layer of bolts shall meet the requirements for Grade 10.9 specified in Table 3 of GB 3098.1-82 Mechanical properties of fasteners - Bolts, screws and studs.
1.4 The fastening axial force of the hexagon nut and plain washer shall meet the requirements of Table 7.
Table 7
d 16 20 22 24
Average value of fastening axial force of each batch, t Nominal 11.1 17.3 21.5 25
Maximum 12.2 19 23.6 27.5
Minimum 10.1 15.7 19.5 22.7
Coefficient of variation of fastening axial force λ ≤10%
where,
Note: Each batch of products shall meet the requirements in Table 7. The maximum quantity of products in each batch is 5,000 pieces. And axial force test shall be carried out in products with the same specification, property grade, furnace number, molding process, heat treatment process and surface treatment process.
1.5 Bolt, nut and thread
1.5.1 The basic dimensions of threads shall meet the requirements for coarse pitch threads specified in GB 196-81 General purpose screw threads - Basic dimensions for diameter from 1 to 600mm.
The tolerance zone of bolt threads shall be Grade 6g specified in GB 197-81 General purpose screw threads - Basic dimensions for diameter from 1 to 600mm. Bolt thread shall be processed by rolling.
The tolerance zone of nut thread shall be Grade 6H specified in GB 197-81.
1.5.2 The smoothness of the thread side shall not be lower than .
1.6 The surface defects of bolts, nuts and washers shall meet the requirements of relevant standards for fastener.
1.7 Other dimensions and geometric tolerances of bolts, nuts and washers shall meet the requirements for Grade C products specified in GB 3103.1-82 Tolerance for fasteners, bolts, screws and nuts.
