Automatic gauge gauge in manual measurement of elongation after break (A) - Database & Sql Blog Articles

Automatic gauge for manual measurement of elongation after break (A)

A

Application in:

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Based on GB/T 228.1

Automatic gauge, including automatic marking machine and automatic gauge length marking machine

The basic features of the automatic gauge:

1. One-button operation, fully automated.

2. Set the gauge length and interval to mark dots or lines effectively.

3. Adjust the tapping force or knife action to minimize specimen damage.

4. High precision through advanced transmission components and intelligent control.

5. Intuitive interface, easy to use, high efficiency.

6. Produces sample gauge lines according to standard requirements.

Manual measurement of elongation after break (A):

Main points:

1. After breaking, align the two parts of the specimen on the same axis.

2. Ensure proper cross-section.

3. Conduct direct measurement under appropriate conditions.

4. Displacement measurement (Appendix H).

5. Elongation at break of 5% or less (Appendix G).

6. Representation and conversion methods.

7. Rounding intervals.

Original gauge length marking:

Mark the original gauge length with small marks, thin lines, or fine ink lines, but avoid gaps that may cause premature failure.

Note:

OH5300 – Adjustable knife force allows for precise and clear gauge lines. A variety of knives with different hardness can be used for special samples. Ink can be applied to the surface, and the knife force adjusted accordingly to achieve a clean, non-damaging line.

OD5350 – Adjust the nod force to create small identification points without causing premature breakage.

For proportional samples, if the difference between the calculated and marked original gauge length is less than 10% L₀, the value can be rounded to the nearest 5mm as per GB/T 8170. The original gauge length should be accurate to ±1%. The parallel length Le is much longer than L₀, so multiple nested gauge lengths can be marked. In some cases, a line parallel to the longitudinal axis can be drawn, and the gauge length marked on this line.

Note: Tianjin Outlet offers full-range standard gauge punching machines or marking machines for 5mm interval dot or line marking.

5mm interval dot or line.

For nested gauge length marking, OH5300 self-standard gauge and OD5350 automatic gauge length punching machine can quickly mark the nested gauge length on the specimen.

A: Residual elongation of the gauge length after breaking (Lu - L0) as a percentage of the original gauge length (L0).

Determination:

The fractured parts of the specimens must be carefully aligned to ensure their axes are on the same line. Special measures should be taken to ensure proper contact after fracture, especially for samples with small cross-sectional areas or low elongation.

Note:

ODC1350 – The double-station break gauge length measuring table facilitates axial alignment of the specimen after breaking, ensuring correct occlusion and eliminating gaps (pre-tightening), improving measurement accuracy and convenience.

The elongation after break should be measured using a gage or measuring device with sufficient resolution (Lu - L0), to within ±0.25mm.

Method 1: Manual measurement method

Before testing, mark the original gauge length (L₀) at the center of the parallel length of the sample, accurate to ±1%. Mark N equal intervals within the gauge length.

After breaking, carefully align the broken parts so their axes are on the same straight line. Take special measures to ensure the broken gauge length is properly determined after contact.

If the distance from the break to the nearest gauge mark is ≥ 1/3 L₀, and the elongation ratio is ≥ the specified minimum, measure the distance between the two marks directly.

If the specimen breaks between two marks, but the distance from the nearest gauge mark is < 1/3 Lâ‚€, the "displacement method" can be used to measure the elongation after break.

See below a, b shown.

If the distance from the break to the nearest gauge mark is < 1/3 L₀, but the elongation after break is ≥ the specified minimum, the "displacement method" can also be used.

OD5350 Automatic marking machine and OH5300 Automatic gauge length marking machine can effectively index or scribe the gauge length and interval, quickly marking N equal intervals. Regardless of the gauge or shape of the specimen, especially small gauges, threaded end samples, step samples, etc., they can ensure no damage to the specimen.

Among them, OH5300 allows free setting of the gauge length and interval (whether decimal or integer).

Elongation at break 5% or less – determination:

For low-ductility materials, traditional methods may not provide accurate results, so Appendix G provides special methods. Make a small mark at one end of the parallel length before the test. Use a gauge set to the gauge length to draw a circle. After breaking, place the specimen on a device and apply axial force via a screw to ensure firm contact during measurement. Draw a second arc with the same radius from the original center. Measure the distance between the two arcs using a microscope or other suitable instrument, accurate to 0.02 mm. Apply dye before testing to make the markings more visible.

OD5350 – Automatic two-point marking function

OH5300 – The automatic gauge length marking machine allows arbitrary setting of gauge length and interval (set to equal, i.e., number of copies = 1) for easy initial L₀ marking.

For proportional samples, if the scale factor k ≠ 5.65, the symbol A should include the scale factor, e.g., A11.3.

For non-proportional samples, the symbol A should include the original gauge length in millimeters, e.g., A80mm.

Fixation of sample result values:

Test results should be revised according to product standards. If no specific requirements are given, the contract should specify rounding to 0.5%.

Elongation after break (A) – Conversion:

Standard 20.3 article stipulates that elongation after break can be measured on a fixed gauge length by agreement before the test, then converted into proportional gauge length elongation using a formula or table (e.g., GB/T 17600.1-1998 “Elongation of steel” Part 1: Carbon steel and low alloy steel; GB/T 17600.2-1998 “Elongation of steel” Part 2: Austenitic steel).

Only when the gauge length, cross-section shape, and area are the same, or the scale factor k is the same, the elongation after break is comparable.

Elongation conversion is approximate and may have some error. It should only be used with mutual agreement.