Grade 12.9 Steel Equal-End Stud Bolt

Grade 12.9 Steel (class 12.9) is the highest common strength class, for high-load machine assembly. When equal-end stud bolt are specified in this grade, the dimensions remain per GB/T 901 / DIN 939; the material determines corrosion behavior (requires plating or black-oxide protection) and the service temperature range (up to approx. +300 °C). Both are covered below with the size table.

Why Choose Grade 12.9 Steel for Equal-End Stud Bolt — GB/T 901 / DIN 939 (Series 093)

The highest common strength class, for high-load machine assembly. For equal-end stud bolt — gb/t 901 / din 939 (series 093), this matters when requires plating or black-oxide protection is the primary requirement.

Mechanical & Physical Properties

Galvanic & Galling Considerations

For equal-end stud bolt — gb/t 901 / din 939 (series 093) 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 Equal-End Stud Bolt — GB/T 901 / DIN 939 (Series 093), 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 Equal-End Stud Bolt — GB/T 901 / DIN 939 (Series 093) Available in Grade 12.9 Steel