Common fastener materials紧固件常用材料
| Material材料 | Typical use典型用途 |
|---|---|
| Low-carbon steel (e.g. 1018, 1022; SWRCH)低碳钢（如 1018、1022，SWRCH 系列） | Class 4.8 and lower bolts, screws, rivets; case-hardened tapping screws4.8 级及以下螺栓、螺钉、铆钉；渗碳处理的自攻螺钉 |
| Medium-carbon and boron steel (e.g. 1035, 45, 10B21, 10B33)中碳钢及硼钢（如 1035、45 号钢、10B21、10B33） | Class 8.8 bolts and screws8.8 级螺栓、螺钉 |
| Alloy steel (e.g. 35CrMo, SCM435, 4140)合金钢（如 35CrMo、SCM435、4140） | Class 10.9 and 12.9, large diameters10.9、12.9 级及大规格高强度件 |
| Austenitic stainless (304 / A2, 316 / A4)奥氏体不锈钢（304 / A2、316 / A4） | Corrosion-resistant fasteners; strengthened by cold working, not by heat treatment耐腐蚀紧固件；靠冷加工强化，不能热处理强化 |
| Martensitic stainless (410)马氏体不锈钢（410） | Hardenable; used for stainless self-drilling and tapping screws可淬火硬化，用于不锈钢自钻、自攻螺钉 |
| Brass, copper, aluminium黄铜、紫铜、铝 | Inserts, electrical parts, light-weight and non-magnetic applications嵌件、导电件、轻量化和无磁场合 |
Heat treatment热处理
- Quenching and tempering — the part is heated, rapidly cooled to harden it, then tempered to the required strength and toughness. Required by ISO 898-1 for property classes 8.8 and above.淬火 + 回火（调质）：加热后快速冷却使其硬化，再回火到所需的强度和韧性。ISO 898-1 规定 8.8 级及以上必须调质处理。
- Case hardening (carburizing) — carbon is diffused into the surface, giving a hard skin over a tough core. Used for tapping, self-drilling and thread-forming screws that must cut or form threads in the mating part.渗碳淬火：使碳渗入表层，形成“外硬内韧”的结构。用于需要在对手件上攻出或挤出螺纹的自攻、自钻、自挤螺钉。
- Annealing — softens the wire before cold forming, especially for alloy steels.退火：冷成型前软化线材，合金钢尤其需要。
Typical heat-treatment defects are incorrect hardness, surface decarburization and mixed parts. Hardness and decarburization should be checked on every batch.常见热处理问题有硬度不合格、表面脱碳和混料。每批都应检查硬度和脱碳层。
Surface treatments表面处理
| Finish表面处理 | Characteristics特点 | Notes注意事项 |
|---|---|---|
| Electro-zinc with trivalent passivation (clear, blue, yellow, black)电镀锌 + 三价钝化（白、蓝白、彩、黑） | Low cost, general indoor corrosion protection成本低，一般室内防护 | Hydrogen embrittlement risk on high-strength parts高强度件有氢脆风险 |
| Zinc-nickel electroplate锌镍合金电镀 | Much better corrosion resistance than plain zinc耐腐蚀性明显优于普通镀锌 | Also electroplated — same embrittlement considerations同属电镀工艺，同样需考虑氢脆 |
| Zinc-flake coating (commonly called “Dacromet”)锌铝涂层（俗称“达克罗”） | High corrosion resistance, non-electrolytic耐腐蚀性高，非电解工艺 | Preferred for class 10.9 and above; thicker, check thread fit10.9 级及以上优先选用；涂层较厚，需注意螺纹配合 |
| Hot-dip galvanizing热浸镀锌 | Thick, long-life outdoor protection涂层厚，户外长效防护 | Structural bolts; needs oversize nut threads多用于钢结构；螺母需加大攻丝 |
| Black oxide发黑 | Black appearance, minimal dimensional change外观黑色，几乎不改变尺寸 | Little corrosion protection on its own; usually oiled本身防锈能力弱，一般需浸油 |
| Phosphating磷化 | Base for oil, lubricant or paint作为油、润滑剂或涂装的底层 | Limited corrosion protection alone单独使用防锈能力有限 |
| Passivation (stainless)钝化（不锈钢） | Restores the protective oxide layer恢复表面保护性氧化膜 | Removes free iron after machining去除加工后残留的游离铁 |
Under RoHS, hexavalent chromium passivation is restricted; trivalent passivation is now the norm. The coating also changes friction and therefore the tightening torque — see Torque and Preload《扭矩与预紧力》. For high-strength parts, see Hydrogen Embrittlement《氢脆》.受 RoHS 限制，六价铬钝化已基本被三价钝化取代。表面处理还会改变摩擦系数，从而影响拧紧扭矩，详见Torque and Preload《扭矩与预紧力》；高强度件请参阅Hydrogen Embrittlement《氢脆》。
This article is general technical information for reference. For a specific application, please confirm against the applicable standard, your drawing, or with our engineers.本文为通用技术资料，仅供参考。具体应用请以相关标准、图纸为准，或咨询我们的技术人员。
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