Material specification page for threaded rod in Grade 12.9 Steel. Covers the grade designation (class 12.9), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to GB/T 15389 / DIN 939.
Why Choose Grade 12.9 Steel for Threaded Rod — GB/T 15389 / DIN 939 (Series 095)
The highest common strength class, for high-load machine assembly. For threaded rod — gb/t 15389 / din 939 (series 095), this matters when requires plating or black-oxide protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | class 12.9 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | up to approx. +300 °C |
| Corrosion characteristic | Requires plating or black-oxide protection |
Corrosion Behavior in Service
Carbon and alloy steel threaded rod — gb/t 15389 / din 939 (series 095) require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.
Comparable Grades
For Threaded Rod — GB/T 15389 / DIN 939 (Series 095), 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 Threaded Rod — GB/T 15389 / DIN 939 (Series 095) Available in Grade 12.9 Steel
| Thread size | Pitch (mm) | Length L (mm) | Engagement depth bm (mm) | Material | Reference standard |
|---|---|---|---|---|---|
| M6 | 1.0 | 50 | 8 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
| M8 | 1.25 | 60 | 10 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
| M10 | 1.5 | 80 | 15 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
| M12 | 1.75 | 100 | 18 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
| M14 | 2.0 | 120 | 21 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
| M16 | 2.0 | 150 | 24 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
| M20 | 2.5 | 180 | 30 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
| M24 | 3.0 | 200 | 36 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
| M30 | 3.5 | 240 | 45 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
| M36 | 4.0 | 280 | 54 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |