+7 (4862) 36-90-36 ABOUT COMPANY CATALOG PRODUCTION TECHNICAL INFORMATION NEWS CONTACTS Fastener hardness Bolt hardness Hardness indicators Strength class 3.6 4.6 4.8 5.6 5.8 6.8 8.8 a 9.8 b 10.9 12.9 d £ 16 s , mm d> 16 s , mm Vickers hardness, HV, F ≥ 98 H not less 95 120 130 155 160 190 250 255 290 320 385 no more 220 d 250 320 335 360 380 435 Brinell hardness, HB, F = 30 D 2 not less 90 114 124 147 152 181 238 242 276 304 366 no more 209 d 238 304 318 342 361 414 Rockwell hardness, HRC not less - - 22 23 28 32 39 no more - - 32 34 37 39 44 a For bolts of strength class 8.8 with a diameter of d £ 16 mm, there is an increased risk of damage to the nut in the event of overtightening, leading to the fact that the generated load exceeds the proof load for the nut specified in GOST R 52628. b Applies only to products with a nominal thread diameter d £ 16 mm. c For building bolting, the limit is 12 mm. d Hardness values measured at the end of bolts, screws and studs shall not exceed 250 HV, 238 HB or 99.5 HRB. Hardness of nuts Hardness indicators Strength class five 6 8 nine ten 12 d £ 16, mm d> 16, mm d £ 16, mm d> 16, mm d £ 16, mm d> 16, mm Vickers hardness, HV not less 130 146 150 170 200 233 188 272 295 no more 302 302 302 302 302 353 302 353 353 Brinell hardness, HB not less 130 146 143 162 193 219 180 258 280 no more 286 286 286 286 286 336 286 336 336 Rockwell hardness, HRC not less eleven 19 18 26 29.2 no more thirty thirty thirty thirty thirty 36 thirty 36 36 © 2017 Parallel All rights reserved. COMPANY PRODUCTION CONTACTS TECHNICAL INFORMATION CATALOG Bolts Screws Nuts Washers and rings Hairpins Foundation bolts Rivets, axles, rollers, cotter pins Engineering details. Metalworking orders +7 (4862) 36-90-36 parallel@bolt57.ru Twitter Facebook In contact with Youtube Website development and promotion