1. Standards and types
GB 5783d: Full thread external hexagon bolt, with the screw part entirely threaded.
GB 5782d: Half threaded external hexagon bolt, with no thread at the end of the screw (bare rod section), and a thread length of approximately 1.5 times the diameter of the bolt.
Standard system: Chinese National Standard (GB), compliant with metric (millimeter) specifications, widely used in fields such as machinery and construction.

2. Structural characteristics
Head: Standard hexagonal shape, easy to install with wrench or socket tools.
Thread: Metric coarse thread (standard M series, such as M6, M12, etc.), thread angle 60 °, compatible with ISO international standards.

Material and grade:
Material: Commonly used carbon steel (such as Q235), alloy steel (such as 35CrMo), or stainless steel (such as A2-70).
Strength level: 4.8, 8.8, 10.9, etc. (the higher the value, the greater the strength).

3. Specification parameters
Example annotation: For example, M12 × 50 represents a nominal diameter of 12mm and a length of 50mm.
Surface treatment: galvanizing (blue and white zinc, color zinc), blackening, Dacromet, etc., to improve anti-corrosion performance.

4. Application scenarios
General machinery: equipment assembly, component connection.
Building structure: Steel structure connection, bracket fixation.
Automobiles and Electricity: Tightening of Medium to High Load Components.

5. Comparison with American standard bolts
Unit difference: metric (millimeters) vs American system (inches).
Thread standard: metric coarse/fine thread (M) vs. American UNC/UNF (UTS).
Strength Identification: Grade Number (e.g. 8.8) vs Grade (such as Grade 5).

6. Precautions
Select the strength grade based on the load (such as grade 8.8 for medium to high strength scenarios).
The bare rod section (GB 5782) can reduce thread wear and is suitable for dynamic loads or situations that require precise positioning.