Examination method for determining position of subsurface inclusion defect of continuous casting billet

A technology of defect location and inspection method, which is applied to determine the position of subcutaneous inclusion defects in continuous casting slabs in the low-magnification structure of casting slabs. In the field of material inspection, it can solve the problem of inability to determine the relationship between defects and solidification structures, and the inability to accurately locate subcutaneous inclusion defects. and other issues to achieve the effect of fast inspection speed, low pollution, and energy saving

Active Publication Date: 2017-03-29
ANGANG STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Solve the problem that the position of the subcutaneous inclusion defect cannot be accurately located by conventional inspection methods, and the relationship between the defect and the solidified tissue cannot be determined

Method used

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  • Examination method for determining position of subsurface inclusion defect of continuous casting billet
  • Examination method for determining position of subsurface inclusion defect of continuous casting billet
  • Examination method for determining position of subsurface inclusion defect of continuous casting billet

Examples

Experimental program
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Effect test

Embodiment 1

[0021] Example 1, test and determine the position of the subcutaneous inclusion defect of the continuous casting slab whose chemical composition is C 0.14wt%; Si 0.5wt%; Mn 0.9wt%; P 0.035wt%; S 0.035wt%; Al 0.015wt%.

[0022] Take the cross-sectional sample of continuous casting billet of this composition, first face mill and grind the sample to achieve a surface finish of Ra≤0.1μm, and then mechanically polish until the surface finish reaches Ra≤0.025μm.

[0023] With the slab sample facing up, use the cold acid etching reagent involved in the present invention to corrode the sample surface for about 0.5-1 minute, and when the surface of the slab sample is observed with the naked eye to show a solidified crystalline structure, Pour hot water above 80°C on the corrosion test surface for 0.5 minutes, and dry it with high-pressure air. At this time, subcutaneous inclusion defects are faintly displayed.

[0024] Heat the 1:1 hydrochloric acid aqueous solution to 60-70°C, place ...

Embodiment 2

[0025] Example 2, the chemical composition is determined to be the position of the subcutaneous inclusion defect of the continuous casting slab containing C 0.17wt%; Si 0.48wt%; Mn 0.8wt%; P 0.029wt%; S 0.035wt%; Al 0.015wt%.

[0026] Take the cross-sectional sample of continuous casting billet of this composition, first face mill and grind the sample to achieve a surface finish of Ra≤0.1μm, and then mechanically polish until the surface finish reaches Ra≤0.025μm.

[0027] With the slab sample facing up, use the cold acid etching reagent involved in the present invention to corrode the sample surface for about 0.5-1 minute, and when the surface of the slab sample is observed with the naked eye to show a solidified crystalline structure, Pour hot water above 80°C on the corrosion test surface for 0.5 minutes, and dry it with high-pressure air. At this time, subcutaneous inclusion defects are faintly displayed.

[0028] Heat the 1:1 hydrochloric acid aqueous solution to 60-70°C...

Embodiment 3

[0030] The inspection determined that the chemical composition was the position of the subcutaneous inclusion defect of the continuous casting slab containing C 0.18wt%; Si 0.41wt%; Mn 0.85wt%; P 0.033wt%; 0.036wt%; Al 0.016wt%.

[0031] Take the cross-sectional sample of continuous casting billet of this composition, first face mill and grind the sample to achieve a surface finish of Ra≤0.1μm, and then mechanically polish until the surface finish reaches Ra≤0.025μm.

[0032]With the slab sample facing up, use the cold acid etching reagent involved in the present invention to corrode the sample surface for about 0.5-1 minute, and when the surface of the slab sample is observed with the naked eye to show a solidified crystalline structure, Pour hot water above 80°C on the corrosion test surface for 0.5 minutes, and dry it with high-pressure air. At this time, subcutaneous inclusion defects are faintly displayed.

[0033] Heat the 1:1 hydrochloric acid aqueous solution to 60-70...

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Abstract

The invention provides a macroscopic examination method for determining a position of a subsurface inclusion defect of a continuous casting billet. The method comprises the steps: firstly, taking a transverse low-magnification sample from the continuous casting billet having the subsurface inclusion defect, and preparing the sample; then corroding the upper surface of the sample with a cold acid etching reagent; next, dipping and etching the sample with a hot acid solution, scrubbing with cold water, and blowing to dry with hot air; and finally, carrying out statistics on the number of aggregative distributed subsurface inclusions, carrying out multi-point measurement, then averaging, and positioning the position of the subsurface inclusion defect in the casting billet. The method can display the position, the form, the distance from the surface of the casting billet and other information of the subsurface inclusion defect of a cross section of the continuous casting billet in a solidification organization structure in an original appearance manner; the problems that the subsurface inclusion defect position cannot be accurately positioned and the relationship between the defect and the solidification structure cannot be determined by a conventional examination method are solved.

Description

technical field [0001] The patent of the invention relates to material inspection in the field of metallurgical analysis, in particular to an inspection method for determining the position of subcutaneous inclusion defects in continuous casting slabs in the low-magnification structure of slabs. Background technique [0002] Subcutaneous inclusions in continuous casting slabs are one of the more common defects in casting slabs. When the subcutaneous inclusions are serious, they will be exposed to the surface during the rolling process of the steel and affect the surface quality of the product. Unexposed subcutaneous inclusions are also It will affect the toughening performance, cold bending performance, stamping performance and other deep processing performance of the product. [0003] One of the keys to control and eliminate subcutaneous inclusion defects in continuous casting billet is to use practical and effective corrosion methods to fully and accurately locate the posit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/88G01N1/32
Inventor 隋晓红张鹏远金星
Owner ANGANG STEEL CO LTD
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