1.How is hardness graded according to Chinese standards?
Soft: Suitable for deep stamping.
Premium Grade: The softest grade, with the best deep-drawing performance, suitable for parts with extremely complex shapes.
Semi-soft: Between soft and low hardness, it has a certain strength and retains a certain degree of moldability.
Low hardness: Obtained through light cold rolling, it has higher strength than the annealed state and is used for molded parts that require a certain strength.
2.What is the hardness of the annealed surface?
The softest type. Used for extremely complex deep-drawing processes, such as automotive oil pans and washing machine inner drums.
3.What is the hardness of a standard tempered surface?
These are commonly seen 2B smooth or 2D matte finished products. They are used for general stamping parts, such as appliance housings and ordinary structural parts.
4.How to choose?
If you need to stamp steel sheets into complex shapes (such as automotive body panels), you should choose annealed (Grade A) or soft (Grade R) steel. If it is only used as a flat sheet or only requires simple bending and strength is required, you can choose 1/4 hard (Grade 4) or harder grades.
5.What are the detection methods?
For thin sheets, Rockwell hardness (HRB) or Vickers hardness (HV) are typically used for testing. When the sheet thickness is too thin (e.g., less than 0.6 mm), tensile testing may be inaccurate, making hardness testing a more reliable method.