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1. Hardness Test

Hardness of steel sheet is closely related to other properties like strength, wear resistance, and workability.

2. Rockwell Hardness Test

Material resistance to indentation is a qualitative indication of its strength. Steel ball or diamond is often used as an indenter. With this system, a hardness number is determined by the difference in penetration depth resulting from an application of initial minor load onto the indenter followed by major load.
Normally, the hardness of BP products are tested with the HR30T scale..

Measurement Methods (Scale)

Scale	Indenter	Initial Minor Load	Major Load
B	Diameter: 1.588mm steel ball	10kg	100kg
30T	Diameter: 1.588mm steel ball	3kg	30kg

3. Vickers Hardness Test

A very small diamond indenter with pyramidal geometry and opposite angle of 136° is forced onto the surface of the specimen. The resulting impression is observed under a microscope and measured. The measurement is then converted into a hardness value. Formula for hardness value: Hv=1.857 p/d2

p: Applied load d: Average diagonal line between opposite angles of indentation

4. Tension Test

Although strength is an important factor of steel plates,an increased strength means decreased tensile, making it weak and susceptible to stress-strain. Tensile properties must be taken into consideration for steel products requiring good strength. Steel sheets with low yield ratio (YP/YS), high modulus of work hardening (N), and high tensile ratio are premium products. In addition, tensile strength and elongation must be in balance. Tensile testing is performed to determine the yield strength, tensile strength, and elongation.

ⓐ Yield Strength (YP) (kg/m²)
Yield strength is measured by dividing the maximum tensile load (kg) that test specimen can bear just before deforming with the circular cross sectional area.

ⓑ Tensile Strength (TS)
Tensile Strength value is measured by dividing the maximum load (kg) that test specimen can sustain without fracture with the circular cross sectional area. After yielding, the stress needed to continue plastic deformation increases to a maximum point and then decreases to an eventual fracture. The tensile strength is the stress at the height of the engineering stress-strain curve.
Fm : Maximum load A : Circular cross-sectional area

ⓒ Elongation (EL)
Higher the elongation means better workability. (L-L0/L1) X 100
L0 : Original length of the specimen
L1 : Elongated length during testing

YR (Yield Ratio) : YR=YP/TS X 100

YP-EL (YP-elongation) : Elongation without increase in load. Products with YP-EL are liable to flaws and stretcher-strain during working.

5. Surface Roughness Test

This measures the roughness of plate surface. Test specimen is placed on the testing table and the needle on the pick-up part is placed onto the surface. It moves at a constant rate to measure the highest surface irregularity.

Rmax. (Maximum height of rough point)

6. Erichsen Test

This test measures the drawability of steel sheets. Steel sheet of 0.1~2.0mm thickness is used for testing. The test piece is punched and pushed down with a 10mm-radius plunger until the test piece cracks. The h-Value, measured when the fracture occured, is the Erichsen value. Usually, larger Erichsen value means better drawability and workability.