ASTM F835 – Alloy Steel Socket Head Cap Screws
ASTM F835 specifies requirements for alloy steel socket head cap screws, with particular emphasis on the chemical composition and mechanical properties of the steel used for these fasteners. The specification establishes requirements for material chemistry, heat treatment and mechanical performance to provide consistent strength and hardness for inch-series socket head cap screws.
The standard provides a basis for controlling the material and performance of the finished fasteners, including requirements related to chemical composition, hardness and tensile properties. These requirements are used together with the applicable dimensional specifications to define the characteristics of ASTM F835 socket head cap screws.
Material Chemical Composition:
ASTM F835 specifies chemical composition requirements for the alloy steel used to manufacture socket head cap screws. The limits on carbon and alloying elements are established to provide a suitable material for the required heat treatment and mechanical performance of the finished fasteners. Phosphorus and sulfur are also controlled within specified limits as part of the material requirements.
The chemical composition requirements are shown in the table below. The specified limits apply to the steel used for ASTM F835 fasteners and should be considered together with the heat-treatment and mechanical-property requirements of the specification.
| Material | Heat Treament | C(min) | C(max) | P(max) | S(max) | B(max) | Tempering temperature(℃） |
|---|---|---|---|---|---|---|---|
| Alloy Steel | Heat treated by quenching in oil | 0.28 | 0.5 | 0.04 | 0.045 | Not Specified | tempering by reheating to at least 650°F |
Mechanical Property:
ASTM F835 establishes mechanical property requirements for alloy steel socket head cap screws to ensure that the finished fasteners achieve the required strength and hardness. The requirements include tensile strength, yield or proof strength and hardness, with the specified values depending on the applicable size range and property requirements of the fastener.
The mechanical properties are achieved through controlled heat treatment and verified by mechanical testing and hardness testing. The requirements specified by ASTM F835 provide a basis for evaluating the load-carrying capability and consistency of the finished socket head cap screws. The applicable mechanical property limits are summarized in the table below.
| Thread Size | Tension Strength(ksi) | Yield Strength(ksi) | Elongation(%) | Reduction of area(%) | Hardness(HRC) |
| ≤0.5 | - | - | - | - | 39-44 |
| ＞0.5 | 170 | 153 | 8% | 35% | 37-44 |
Minimum Ultimate Tensile Loads
| Thread Size | Stress Area, in² | Button and Countersunk Heads, Tensile Load, min lb⁴ | |||
| Coarse | Fine | Coarse | Fine | Coarse Thread Series | Fine Thread Series |
| … | 0.060-80 | … | 0.00180 | … | 260 |
| 0.073-64 | 0.073-72 | 0.00263 | 0.00278 | 380 | 400 |
| 0.086-56 | 0.086-64 | 0.00370 | 0.00394 | 530 | 570 |
| 0.099-48 | 0.099-56 | 0.00487 | 0.00523 | 700 | 750 |
| 0.112-40 | 0.112-48 | 0.00604 | 0.00661 | 870 | 950 |
| 0.125-40 | 0.125-44 | 0.00796 | 0.00830 | 1150 | 1200 |
| 0.138-32 | 0.138-40 | 0.00909 | 0.01015 | 1310 | 1460 |
| 0.164-32 | 0.164-36 | 0.0140 | 0.01474 | 2020 | 2120 |
| 0.190-24 | 0.190-32 | 0.0175 | 0.0200 | 2520 | 2900 |
| 0.250-20 | 0.250-28 | 0.0318 | 0.0364 | 4580 | 5240 |
| 0.3125-18 | 0.3125-24 | 0.0524 | 0.0580 | 7550 | 8350 |
| 0.375-16 | 0.375-24 | 0.0775 | 0.0878 | 11200 | 12600 |
| 0.4375-14 | 0.4375-20 | 0.1063 | 0.1187 | 15300 | 17100 |
| 0.500-13 | 0.500-20 | 0.1419 | 0.1599 | 20400 | 23000 |
| 0.625-11 | 0.625-18 | 0.226 | 0.256 | 30700 | 34800 |
| 0.750-10 | 0.750-16 | 0.334 | 0.373 | 45400 | 50700 |
| 0.875-9 | 0.875-14 | 0.462 | 0.509 | 62800 | 69200 |
| 1.000-8 | 1.000-12 | 0.606 | 0.663 | 82400 | 90400 |
| … | 1.00-14 UNSᶜ | … | 0.680 | … | 92500 |
| 1.125-7 | 1.125-12 | 0.763 | 0.858 | 104000 | 116400 |
| 1.250-7 | 1.250-12 | 0.969 | 1.073 | 132000 | 146000 |
| 1.375-6 | 1.375-12 | 1.155 | 1.315 | 157000 | 179000 |
| 1.500-6 | 1.500-12 | 1.405 | 1.581 | 191000 | 215000 |