JIS-B-1051-1991-ENG.pdf
STD-JIS B 305L-ENGL 3773 D 4733b08 0553264 T 4 3 JAPANESE INDUSTRIAL STANDARD JIS B 1051 : 1991 Mechanical properties of steel bolts and screws September, 1998 ERRATA In line 4 of 4.2.5 (21, Page 13 and in line 4 of 4.2.8 (21, Page 15 Error JIS Z 2251 Correct JIS 2 2244 Remarks : This erratum is for correcting the third edition of this Standard. Japanese Standards Association J'IS UDC 621.882.2:669.14:539.4 -JAPANESE INDUSTRIAL STANDARD Mechanical properties for steel bolts and screws Translated and Published bY Japanese Standards Association Printed in Japan 21 s J I S BULO51 91 4933b08 0083957 9 In the event of any doubt arising, the original Standard in Japanese is to be fïnal authority. -,-,- JIS BU1851 91 SS 4733608 0083958 C l = a I a 0 a UDC 621.882.2: 669.14: 539.4 JAPANESE INDUSTRIAL STANDARD J I S Mechanical properties of steel bolts and screws B 1051-1991 i. Scope This Japanese Industrial Standard specifies the mechanical properties and the testing, inspection, and marking of steel bolts and machine screws at ambient temperature( 2, which satisfy the conditions of Table i ( I ) . 4 T to 7 T shall be in accordance with the Annex. The mechanical properties of bolts and machine screws in strength classes Notes (l) External threaded fasteners shall be used as a general term for steel bolts and machine screws applicable to this standard. The term Product shall be used for completed external threaded fasteners used in their entirety in testing, to distinguish from partial test specimens. ( 2, Ambient temperature, as stipulated in JIS Z 8703, is within the range 5 to 35OC. Remarks 1. This Standard does not apply to external threaded fasteners for which weldability , corrosion resistance, heat resistance against temperature of not lower than 3OO0C, and cold resistance against temperature of not higher than -5OOC are required. 2. This Standard may be applied to external threaded fasteners with a size beyond the range of this standard (forl example, a size exceeding 39 mm in nominal diameter of the screw thread) if the requirements for the strength classes specified in this Standard are satisfied. 3. The values for mechanical properties specified in this Standard apply at ambient temperature. The values differ somewhat for temperatures above or below the range of the ambient temperature. For reference, Informative Reference Table 1, at the end of this Standard, provides examples on the decrease in the yield point between 100 to 300OC. The Standards cited in this Standard are listed in Attached Table 1. 4. 5. The body of this Standard is in accordance with IS0 898- 1: 1988 Mechanical properties of fasteners-Part 1: Bolts, screws and studs 6. In this standard, units and values given in are in accordance with the conventional units, and are provided for informative reference. (1 N/mm2= 1 MPa) -,-,- 2 B 1051-1991 Table 1. External Threaded Fasteners Applicable to this Standard Item Applicable External thread fastener Types of external threaded fastener External threaded fasteners such as bolts, studs bolts, machine screws, etc., for which minimum mechanical properties are required , whether or not there is a head, and regardless of the shape. However, set screws are excluded. Screw thread shape Range of the nominal diameter of screw threads Materials Screw thread with the standard shape, nominal diameter, and pitch of JIS B 0205 and JIS B 0207. 1.6 to 39 mm Carbon steel and alloy steel 2. Mechanical Properties 2.1 Indication o£ the Strength Class The strength class of external threaded fasteners, based on the mechanical properties, shall be indicated by a two or three digit number which contains adecimal point , as shown in Table 2. The X-axis indicates the designated tensile strength (N/mm2), and the Y-axis indicates the rupture elongation (%) . The digits before the decimal point indicate 1/100 of the designated tensile strength (N/mm2) ( 3), and the digit after the decimal point indicates ten times the ratio of the designated lower yield point (3) or the designated proof stress ( 3 ) to the designated tensile strength ) N/mm2 (See Informative designated Seld point or designated proof stress designated tensile strength ( Reference Table 1). product of the digits before the decimal point and the digits after the decimal point by 10 yields the designated yield point or the designated proof stress (N/mm2). Therefore , the value obtained by multiplying the , Note ( 3, The designated tensile strength, designated yield point, and designated proof stress have been set for convenience in the strength classes, and the minimum values of the tensile strength and yield point (or proof stress) as applied to external threaded fasteners.shal1 be equal to or larger than these designated values (see Table 3). -,-,- J I S B*l1051 91 = 4933b08 0083960 9 I 25 30 3 B 1051-1991 3.; Table 2. Strength Class System Digit after the decimal point in the strength chass . .6 .8 .9 Informative Reference Table 1. Ratio of the Yield Point (or Proof Stress) to the Tensile Strength Nominal lower yield point (or nominal proof stress). Nominal tensile stress x 100 % 1 60 1 80 1 90 2.2 Mechanical Properties for Each Strength Class The mechanical properties for each strength class of external threaded fasteners shall comply with Table 3 when subjected to the tests of Clause 4. -,-,- J I S B*lO!il 91 4933b08 0083ïbl O W Nominal Min Min.(*) Max. 4 B' 1051-1991 3.6 4.6 4.8 5.6 5.8 6.8 8.8 d616 d16 (6) 300 400 500 600 800 800 330 400 420 500 520 600 800 830 (33.7) (40.8) (42.8) (51.0) (53.0) (61.2) (81.6) (84.6) 95 120 130 155 160 190 250 255 250 320 335 Table 3. Mechanical Properties v) Mechanical properties I Strength class Min.(') Max. Tensile strength( 7, 90 114 124 147 152 181 238 242 276 304 238 304 318 342 361 N/mm2 kgf/mm2 Min. ( ' - 22 23 28 32 Max. - 32 34 37 39 I 39 44 1 Vickersydness 64Q 660 720 (65.31 (67.3) (73.4) 0.91 0.91 0.90 580 600 650 (59.1) (61.2) (66.3) 12 12 10 94Q (95.9) 0.88 830 (84.6) 9 Brinell . HB hardness Stress ratio (lfj N/mmz kgf/mm2) Min. Rockwell hardness 0.94 0.94 0.91 0.93 0.90 0.92 180 225 310 280 380 4 4 û i18.4) (22.9) (31.6) (28.6) (38.7) (4.9) 25 22 14 20 10 8 Surface hardness HV Yielii point( lo) N/mm2 kgf/mm2) Impact energy J kgf-m) Min. Proof N/mm2 kgf/mm2) stress Q (9 - - 30 30 25 20 15 25 (2.55) (3.06) (3.06) (2.55) (2.04) i1.53) Proof load stress (“1 Strength of head percussion Decarbu- Height Of non: Min. :fation decarburized threaded part E mm portion (15) . Depth of ferrite. Max. decarburized layer G mm % Elon ation after fracfure Wedge tensile strength The joint of head and body shall be free from cracks(14), - 1 2 3 3Hi THI THI - O. 015 900 1000 $ 900 104.0 12.9 - 1 200 1220 124) 385 435 366 414 640 I 640 I 720 I 900 I 1080 0.88 970 (98.9) 8 Notes ( 5, Applies to bolts and machine screws of a minimum 12 mm in d16 nominal diameter of screw thread for bolts for steel structures. ( 6 , Applies to external threaded fasteners of a maximum 16 mm in nominal diameter of screw thread. ( 7, The tensile strength applies to external threaded fastener with a minimum nominal length of 2.5 d ( d is the nominal diameter of the screw). -,-,- ( lo) The yield point shall be used where it is distinct. Where the yield point is not distinct, with the proof stress at a 0.2 % permanent elongation shali be used. For the proof load stress test , the proof load value in Attached Tables 4 and 5 apply. A permanent elongation may not occur with these values. ( li) JPS B*LBCL îL 4933608 tIR83962 2 = 5 B 1051-1991 For the minimum tensile strength of the product, the .minimum tensile load in Attached Table 2 or 3 applies. The minimum values for hardness apply when the nominal length is less than 2.5 ci and , for some reason such as special shape, the tensile test could not be performed. For products of strength classes 8.8 to 12.9, the surface hardness shall be such that the value of the Vickers hardness is a maximum of 30 greater than the internal hardness (test load, O. 3 kgf) . Further, the surface hardness of products of strength class 10.9 may not exceed HV 390. (') ( ') ( 12) Ratio of the proof load stress and the minimum yield point (or the minimum proof stress) (13) For the minimum wedge tensile strength, the minimum tensile loads in Attached Tables 2 and 3 apply, The tensile rupture shall be produced at the threaded portion or the body, but it shall not be produced at the joint of the head and body. Cracks of complete screw threads which are produced at the free threaded portion may develop into a rupture after enlarging into the underhead fillet or into the head. (I4) Cracks of complete screw threads may be produced at the first thread ridge of the head side, as long as the head is not wrested away. (I5) See Fig. 1. -,-,- 'JIS B*LOSL 91 W 4933608 0083963 LI E 4 6 B 1051-1991 Fig. 1. Decarburization of the Threaded Portion Ferrite decarburized layer( 16) Partial decarburized layer( 17) 1 I I i Nondecarburized part (base metal) H, and -E Unit: mm (minimum) Values Notes ( 16) The layer of ferrite that has been decarburized from the surface of the thread ridge. G is the depth of the ferrite decarburized layer from the surface of the pitch line. ( 17) The martensite. is slightly visible and, due. to the loss of carbon, the hardness is clearly lower than that of the base metal. (I“) Height of the thread ridge in maximum part of the body. 3. Materials and Heat Treatment The materials and heat treatment for the different strength classes of external threaded fasteners shall be as specified in Table 4. The minimum tempering temperatures of this table shall apply to materials in strength classes 8.8 to 12.9, and the limit of chemical components shali apply to materials for which the tension test can not be performed due to short length. -,-,- J I S B*LOSL 91 M 4933608 0083964 b 7 B 1051-1991 Table 4. Materials and Heat Treatment Tempering tempera- ture( 6, O C Chemical components (check analysis) % Strength class Material and heat treatment C P Max. S Min. Min. Max. Max. O . 06 O . 06 3.6( l9) o. 20 O . 05 Carbon steel 4.6( 19) Carbon steel O . 55 O . 05 4.8( 19) 0.55 0.05 0.06 5.6 Carbon steel 0.15 5.8( l9) 0.06 Carbon steel 0.55 0.05 6.8( 19) 8.8( 20) Carbon steel con- taining additives (B , Mn, or Cr) , Quenching and tempering Carbon steel, quenched and temp enxl. ( 25) O . 15 O . 40 O . 035 O . 035 425 O. 25 o. 55 O . 035 O. 035 9.8 Carbon steel con- taining additives (B, Mn, or Cr), quenched and tempered Carbon steel, quenched and tempered ( 25) O. 15 O . 35 O . 035 O. 035 425 O. 25 O . 55 O . 035 D. 035 10.9( 21) Carbon steel con- taining additives (B, Mn, or Cr), quenched and tempered (25) D. 15 o. 35 0.035 O . 035 340 -,-,- JIS B*l05l 91 = 4933608 01383965 8 8 B 1051-1991 Table 4 (Continued) I Strength Material and heat class treatment 10.9( 22) Carbon. steel, quenched and tempered Carbon steel con- taining additives (B, M n or Cr), quenched and tempered Alloy steel( 24), quenched and tempered 12.9 Alloy steel( 24), ( 22) ( 23) quenched and tempered Chemical components (check analysis) % C lp Min. Max, Max 44- 0.25 I 0.55 1 0.035 I I 0.20 I 0.50 I 0.035 s Max. O. 035 O. 035 O. 035 O. 035 Tempering tempera- ture( 6, O C Min 425 380 Notes ( 19) Free-cutting steel may be used for these strength classes + The maximum contents of S, P, and Pb shall be as follows: S: 0.34 % P: 0.11 % Pb: 0.35 % Where sufficient hardenability is required for external threaded fasteners of more than 20 mm in nominal diameter, the material for strength class 10.9 should be used. External threaded fasteners of this strength class shall be identified by underlining the strength class (Refer to 6.1). For the materials of these property classes, it is intended that there should be a sufficient hardenability to ensure a structure consisting of approximately 90 % martensite in the core of threaded sections for the fasteners in the IIas-hardenedII condition before tempering. For external threaded fasteners of the strength class, there shall be no build-up of white phosphorus detectable by a optical microscope on the surface subjected to tensile stress. This alloy shall include at least one of the following elements: Chromium nickel, molybdenum, and vanadium. For boron alloys where the carbon content is 0.25 % or less (ladle analysis value), the manganese content shall be a minimum of 0.6 % for class 8.8, and a minimum of 0.7 % for classes 9.8 and 10.9. JIS B*LOSL 91 W 4933608 00839bb T Permanent elongation due to proof load stress Hardness, difference between the surface hardness and the core hardness Whether cracks appear at the joint of the head and body or not. Impact energy 9 B 1051-1991 4.2.4 4.2.5 4.2.6 4.2.7 ( 26) When external threaded fasteners of strength class 8.8 to 12.9 are tested in accordance with 4.3 y the difference in average values of hardness shall be less than a Vickers hardness of 20. 4. Testing. 4.1 Tests to be Performed The tests to determine the mechanical properties of external threaded fasteners shall be as given in Table 5. Test Tensile test of a test piece Tensile test of a product Wedge tensile test Proof load test Hardness test Head percussion test Impact test Decarburized layer test Retempering test Table 5. Tests Section describing the test method Mechanical properties tested 4.2.1 Tensile strength, yield point or proof stress y rupture elongation Maximum tensile load y rupture location Maximum tensile load, rupture location 4.2.2 4.2.3 Height of the nondecarburized part at the threaded portion, depth of the ferrite decarburized layer at the threaded portion 4.2.8 Hardness before and after retempering 4.3 4.2 Testing of Mechanical Properties 4.2.1 Tensile Test of a Test Piece Prepare a test piece (see Fig. 2) in accordance with No. 14 A of JIS Z 2201 perform the tensile test in accordance with JIS Z 2241, and examine the tensile strength, yield point (or proof stress), and rupture elongation. The diameter of the parallel part of a test piece taken from an external threaded fastener of more than 16 mm in nominal diameter which has been heat treated shall not be less than the original diameter by 25 % oil more( 27), J ï S B*I05I 91 m Y9336148 0083969 I m 10 B 1051-1991 Note ( 27) If the diameter is reduced by 25 %, the sectional area of the parallel part becomes approx. 44 % of the sectional area of the original diameter. Fig, 2. Tencile Test Piece d : nominal diameter of the screw thread do : b : diameter of the parallel part (make smaller than the minor diameter of the screw thread) length of the threaded portion ( b 2 d ) length of the p
