Grade 12.9 Steel Socket Head Shoulder Screw

Grade 12.9 Steel Socket Head Shoulder Screw combine the dimensional form of GB/T 5281 / ISO 7379 with the material properties of grade class 12.9: requires plating or black-oxide protection, magnetic, service range up to approx. +300 °C. This page summarizes the grade data, its corrosion behavior in service, the comparable grades, and the sizes supplied.

Why Choose Grade 12.9 Steel for Socket Head Shoulder Screw — GB/T 5281 / ISO 7379 (Series 017)

The highest common strength class, for high-load machine assembly. For socket head shoulder screw — gb/t 5281 / iso 7379 (series 017), this matters when requires plating or black-oxide protection is the primary requirement.

Mechanical & Physical Properties

Galvanic & Galling Considerations

For socket head shoulder screw — gb/t 5281 / iso 7379 (series 017) in steel, the dominant compatibility issue is hydrogen embrittlement at high property classes (10.9 and above) when electroplated. Plating must be followed by an appropriate baking treatment, or a non-electroplated finish (mechanical zinc, zinc flake) should be substituted.

Comparable Grades

For Socket Head Shoulder Screw — GB/T 5281 / ISO 7379 (Series 017), class 8.8 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.

Sizes of Socket Head Shoulder Screw — GB/T 5281 / ISO 7379 (Series 017) Available in Grade 12.9 Steel