Technical Reference for Hexagon Nuts & Various Nuts
Nuts are usually made of various steels, stainless steels, copper or aluminium. For different usage and working conditions, nuts generally can be classified to low strength, middle strength and high strength. This classification are mainly according to the material, process, mechanical properties.
Carbon Steel and Alloy Steel Hex Nuts and Hex Flange Nuts
The relative standards for nuts classification are SAE J995, Grade 2, 5 and 8, equals to metric system, ISO/DIN standard class 5, 8 and 8.
SAE J995 Gr. 2 nuts are the most common used low strength nuts, (also equals to ISO/DIN Class 5). Its made from low carbon steel, for example, C1010 steels.
SAE J995 Gr. 5 nuts are middle strength nuts, which equals to ISO/DIN Class 8 nuts. Generally made of middle carbon steel, for example C1020, C1035 or C1045 steels. Its used in some structure project, normally the finished nuts were tempered and quenched to reach a higher strength.
SAE J995 Gr. 8 nuts are the high strength fasteners, which are designed for heavy structure project or bridge, high way constructions. Its mostly made of alloy steel, for example 4140, Cr42Mo, etc. The finished Nuts need to be tempered and quenched.
Material reference guide for SAE J995 hex and hex flange nuts
| SAE J995. | C max. | Mn min | P max | S max |
|---|---|---|---|---|
| Gr.2 | 0.47 | - | 0.12 | 0.15 |
| Gr 5 | 0.55 | 0.3 | 0.05 | 0.15 |
| Gr 8 | 0.55 | 0.3 | 0.04 | 0.05 |
Mechanical properties guide for SAE J995 hex nuts and hex flange nuts
| SAE J995. | Hardness | Proof Strength | Heat Treatment | Material |
|---|---|---|---|---|
| Gr.2 1/4"-1-1/2" | HRC 32 max | - | no | low carbon steel |
| Gr 5 1/4"-1" | HRC 32 max | 120,000 psi | optional | middle carbon steel |
| >1"-1-1/2" | 105,000 psi | |||
| Gr 8 1/4"-5/8" | HRC 24-32 | 150,000 psi | tempered & quenched | middle carbon steels or alloy steels |
| >5/8"-1" | HRC 26-34 | |||
| >1" | HRC 26-36 |
There are more standards for nuts, both inch and metric system, below are reference guides only.