Specifying Custom Machined Component — GB/T 5782 / ISO 4014 (Series 004) in Grade 12.9 Steel pairs the dimensional form of Custom Machined Component — GB/T 5782 / ISO 4014 (Series 004) (GB/T 5782 / ISO 4014) with the engineering properties of Grade 12.9 Steel. This page explains when to choose the grade, how it behaves in service, and which grades to compare it against.
Why Choose Grade 12.9 Steel for Custom Machined Component — GB/T 5782 / ISO 4014 (Series 004)
The highest common strength class, for high-load machine assembly. For custom machined component — gb/t 5782 / iso 4014 (series 004), 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 custom machined component — gb/t 5782 / iso 4014 (series 004) 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 Custom Machined Component — GB/T 5782 / ISO 4014 (Series 004), 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 Custom Machined Component — GB/T 5782 / ISO 4014 (Series 004) Available in Grade 12.9 Steel
| Size designation | Outer diameter / width (mm) | Length / height (mm) | Bore / thread (mm) | Material | Reference standard |
|---|---|---|---|---|---|
| Size 1 | 10 | 20 | 6 | C45 carbon steel | GB/T 1804-m |
| Size 2 | 12 | 25 | 8 | C45 carbon steel | GB/T 1804-m |
| Size 3 | 16 | 32 | 10 | C45 carbon steel | GB/T 1804-m |
| Size 4 | 20 | 40 | 12 | C45 carbon steel | GB/T 1804-m |
| Size 5 | 25 | 50 | 16 | C45 carbon steel | GB/T 1804-m |
| Size 6 | 32 | 63 | 20 | C45 carbon steel | GB/T 1804-m |
| Size 7 | 40 | 80 | 25 | C45 carbon steel | GB/T 1804-m |
| Size 8 | 50 | 100 | 30 | C45 carbon steel | GB/T 1804-m |