1、HEAT TREATMENT PROCEDURE INSPECTION
1.1 Heat-treatment procedure inspection refers to tests on steel round bars, in the duration of heat treatment production line, which, mechanical properties, hardness, impact absorb energy at low temperature tests are the mainly part.
3.2 Sampling: according to Table 3
Table 3 Heat-treatment procedure inspection
| Grade | Rm/Mpa | Rp0.2/Mpa | A% | Z% | -40℃Akv2/J | Hardness | Height of partial-decarburization on threads | Depth of complete decarburization on threads | Decarburization of roots mm | Grain size晶粒度级别 | Metallographic structure金相组织 |
| 10.9 | ≥1040 | ≥940 | ≥9 | ≥48 | ≥50 | HRC 32-39 | 2/3H1 | ≤0.015mm | Shall be free of complete decarburization, depth of partial decarburization≤0.050mm | ≥9.5 | Tempered sorbite回火索氏体 |
| 8.8 | ≥830 | ≥660 | ≥12 | ≥52 | ≥70 | HRC 23-34 | 1/2H1 | ≤0.015mm | Shall be free of complete decarburization, depth of partial decarburization≤0.050mm | ≥9.5 | tempered sorbite+few ferrit 回火索氏体+少量铁素体 |
| sampling | 1/bundle | 1/bundle | 1/bundle | 1/bundle | 1/bundle | 2/shift | 1/shift | 1/shift | 1/shift | 1个/heat炉 | 1个/heat炉 |
If heat-treatment procedure inspection fail during production, main control program must be adjusted according to Table 3 requirements, after which, production continues.
3.3 Table 3 above is only apply to high-strength anchor bolt of grade 8.8 and 10.9. If other grade specified, inspection requirements accotding to “Production notification”
3.4 Relative documents: “Test records of products”, “Test records of impact energy”, “Heat-treated materials——Test records of hardness”, “Heat-treated materials——Test records of decarburization on threads”, “Heat-treated materials——Test records of grain size”, “Disposal records of unqualified materials”
3.5 Measuring instruments: : hydraulic servo tensile testing machine, semi-automatic impact tester, low temperature instrument, rockwell hardness tester, metalloscope.
3.6 Reference standard：GB/T3098.1、GB/T228.1 、Q/GW-206066-2016 、GB/T229 、GB/T230.1 、GB/T6394
Post time: Jun-17-2020