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螺栓强度等级（4.6–12.9）
根据 ISO 898-1 标准查找任何螺栓性能等级的机械性能——抗拉强度、屈服强度、验证应力、硬度——并计算任何公制螺纹尺寸的验证载荷。
本计算器由 Vibromera 工程团队开发并验证，该团队也是 Balanset 便携式平衡仪器的制造商。
成果
| 班级 | Rm（MPa） | Rp0.2（MPa） | 验证应力 Sp（MPa） | 延伸率 % | 洛氏硬度 C 标尺 | 材料 |
|---|
解读性能等级标识
两位数系统（例如，8.8）对螺栓的关键机械性能进行了编码：
对于等级 8.8：Rm = 8 × 100 = 800 兆帕，Rp0.2 = 8 × 8 × 10 = 640 MPa。
验证载荷计算
验证载荷是指螺栓在不发生永久变形的情况下必须承受的最大力：
其中 Sp 是验证应力，As 是 ISO 898-1 标准规定的拉伸应力面积。
极限拉伸载荷
已知： 8.8 级，M12（A）s = 84.3 平方毫米)，d ≤ 16 毫米 → Sp = 580 兆帕
验证载荷 Fp = 580 × 84.3 = 48,894 牛顿 ≈ 48.9 千牛顿
拉伸载荷 Ft = 800 × 84.3 = 67,440 牛顿 ≈ 67.4 千牛顿
⚠️ 注意： 对于 8.8 类，Sp 当 d ≤ 16 mm 时，= 580 MPa，Sp 当 d ＞ 16 mm 时，S = 600 MPa。这是因为较大的螺栓具有更高的可硬化截面与总截面之比。
ℹ️ 设计小贴士： 螺栓预紧力目标值通常为验证载荷的 75–90%。拧紧过程中切勿超过验证载荷。对于关键连接，请使用校准扭矩扳手或角度控制拧紧方式。
The designation is a coded system per ISO 898-1:
- First number × 100 = nominal tensile strength Rm in MPa
- First × second × 10 = nominal yield strength Rp0.2 in MPa
For class 8.8: Rm = 8 × 100 = 800 MPa, Rp0.2 = 8 × 8 × 10 = 640 MPa.
The second digit thus represents the yield-to-tensile ratio (0.8 = 80%).
Rp0.2 (yield strength) is the stress causing 0.2% permanent elongation — determined by tensile testing.
Sp (proof stress) is a lower, guaranteed minimum stress the bolt must withstand with zero permanent set — used for proof load testing per ISO 898-1.
Typically Sp ≈ 90–95% of Rp0.2. The proof load Fp = Sp × As is the key parameter for bolt specification.
8.8 is the most common class for general engineering:
- Good strength (Rm = 800 MPa) with adequate ductility
- Suitable for most machine frames, flanges, brackets
- Cost-effective, readily available
10.9 is used when higher clamp force is needed:
- Automotive engine/chassis (OEM standard)
- Structural steel connections (EN 14399)
- High-vibration environments requiring higher preload
- Space-constrained joints (smaller bolt, same force)
12.9 is for the most demanding applications where maximum preload per bolt is critical, e.g. precision machinery, motorsport.
Per ISO 898-1, hex bolts must be permanently marked with:
- Property class — e.g. "8.8", "10.9", "12.9"
- Manufacturer’s ID — symbol or code
Marking location: top or side of hex head. Socket head cap screws: side of head or in the recess.
Unmarked bolts should be assumed ≤ class 4.6 and must not be used in structural applications.
Proof load Fp = Sp × As
- Sp = proof stress (MPa) from ISO 898-1 for the chosen property class
- As = tensile stress area (mm²) for the thread size per ISO 898-1
- Result is in Newtons (÷ 1000 for kN)
The proof load test per ISO 898-1 applies this force axially for 15 seconds. The bolt must not show permanent elongation.
本页所述的操作流程由 Vibromera 团队使用 Balanset-1A（一款用于现场转子平衡的便携式双通道动平衡仪及振动分析仪）开发并经过实地测试。
专业现场平衡仪器和软件。已在50多个国家使用。
