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Experiment method for realizing in-situ observation on inclusion in bearing steel liquid

An experimental method and bearing steel technology, applied in the field of steel inclusion control, can solve the problems of unresolved, high electron beam temperature, deformation, etc., and achieve the effects of convenient and uniform heating, reliable observation results, and simple experimental methods.

Inactive Publication Date: 2016-07-06
BAOSHAN IRON & STEEL CO LTD
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  • Application Information

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Problems solved by technology

The electrolytic method can indeed observe the whole picture of the inclusions, but the inclusions observed by electrolysis are still the inclusions in the molten steel that evolve after solidification, and cannot fully reflect the actual state of the inclusions in the molten steel
[0007] In order to observe the inclusions in the molten steel, the patent EP1361432 (B1) provides a technology that utilizes suspension smelting samples and then cooling to observe the inclusions, which can quantitatively analyze the size of the inclusions. The technical advantage is that the suspension smelting avoids the During the melting process, it is polluted by the refractory material of the bearing sample. However, this technology has the problems that the melting temperature is difficult to control and the sample is seriously deformed after cooling, and the complete shape of the inclusions cannot be observed.
Relevant documents of Japan’s Nippon Steel Corporation have published the method of extracting inclusions by melting samples with electron beams. However, the temperature of electron beams is too high, which has a great influence on the formation temperature of inclusions.
ArcelorMittal Steel Company recently proposed a method for rapid and comprehensive analysis of inclusions. The sample is prepared into a button shape. After the sample is remelted with resistance heating in a specific device, the inclusions can fully float to the surface. The shape of the inclusions can be fully observed by using the scanning electron microscope. However, due to resistance heating, the sample cannot be guaranteed not to be polluted by the refractory material of the loaded sample during the remelting process, nor can it be guaranteed that the sample will not be re-oxidized after high temperature heating
High-temperature confocal laser microscopy is an ideal tool for in-situ observation of samples. It has been widely used in the field of material research. It can observe the crystal growth and phase transition during the solidification of steel. Some scholars also try to melt the sample. Observing the movement behavior of inclusions, but did not propose the difference between inclusions in molten steel and inclusions after slow solidification of molten steel, and also did not propose a method for in-situ observation of inclusions in molten steel
[0008] The inclusions in bearing steel are mainly composite inclusions containing aluminum, calcium, magnesium, silicon, manganese, oxygen and sulfur. The inclusions in molten steel are very different from those after slow cooling and solidification of molten steel. It is difficult to judge the inclusion behavior in molten steel by in-situ observation

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  • Experiment method for realizing in-situ observation on inclusion in bearing steel liquid
  • Experiment method for realizing in-situ observation on inclusion in bearing steel liquid
  • Experiment method for realizing in-situ observation on inclusion in bearing steel liquid

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Experimental program
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Effect test

Embodiment 1

[0052] After sampling from the high-end bearing steel finished product, the steps of this embodiment are as follows:

[0053] 1) A cylindrical sample processed by wire cutting of the bearing steel sample, the sample diameter is 5mm, and the height is 3mm. After the sample is polished by sandpaper, it is placed in the heating chamber of a high-temperature confocal laser microscope, and the sample is placed in an alumina crucible. Inside, the chamber is evacuated and fed with a pure argon flow to protect the sample from oxidation.

[0054] 1) Heat the sample to 1250°C at a heating rate of 120°C / min, then slowly heat the sample at a heating rate of 25°C / min until the upper surface is completely melted, and then rise to the highest temperature at a rate of 25°C / min 1500°C, heat preservation at the highest temperature for 20 seconds, observe the inclusion movement and collision behavior at a 200-fold magnification during the heat preservation process, and then rapidly cool to 950°C...

Embodiment 2

[0058] After sampling from the high-end bearing steel finished product, the steps of this embodiment are as follows:

[0059] 1) A cylindrical sample processed by wire cutting of the bearing steel sample, the sample diameter is 6 mm, and the height is 4 mm. After the sample is polished by sandpaper, it is placed in the heating chamber of a high-temperature confocal laser microscope, and the sample is placed in an alumina crucible. Inside, the chamber is evacuated and fed with a pure argon flow to protect the sample from oxidation.

[0060] Heat the sample to 1200°C at a heating rate of 140°C / min, then slowly heat the sample at a heating rate of 30°C / min until the upper surface is completely melted, and then rise to a maximum temperature of 1420°C at a rate of 30°C / min , hold at the highest temperature for 40 seconds, observe the inclusion movement and collision behavior at a 50-fold magnification during the holding process, and then rapidly cool to 1000°C at a cooling rate of ...

Embodiment 3

[0064] After sampling from the high-end bearing steel finished product, the steps of this embodiment are as follows:

[0065] 1) A cylindrical sample processed by wire cutting of the bearing steel sample, the sample diameter is 4mm, and the height is 3mm. After the sample is polished by sandpaper, it is placed in the heating chamber of a high-temperature confocal laser microscope, and the sample is placed in a magnesium oxide crucible. Inside, the chamber is evacuated and fed with a pure argon flow to protect the sample from oxidation.

[0066] Heat the sample to 1250°C at a heating rate of 100°C / min, then slowly heat the sample at a heating rate of 20°C / min until the upper surface is completely melted, and then rise to a maximum temperature of 1450°C at a rate of 20°C / min , hold at the highest temperature for 30 seconds, observe the inclusion movement and collision behavior at a 500-fold magnification during the holding process, and then rapidly cool to 950°C at a cooling rat...

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Abstract

The invention provides an experimental method for in-situ observation of inclusions in bearing steel. A cylindrical sample is processed by wire-cutting the bearing steel sample. After evacuating the interior, a pure argon flow is introduced to protect the sample from oxidation. Quickly raise the temperature of the sample to 1150-1250°C, then slowly raise the sample until the sample melts, keep it at the highest temperature for 20-40s, observe the inclusion movement and collision behavior at high temperature, and then rapidly cool it to 900-1000°C , and finally slowly cooled to room temperature, after the sample is taken out, enter the electron microscope SEM to observe the shape of the inclusions and use the energy spectrum to analyze its composition. Rapid cooling can make the inclusions basically maintain the state at the steelmaking temperature. In situ observation of behavior, overall appearance, and composition.

Description

technical field [0001] The invention relates to the field of iron and steel inclusion control. Specifically, the invention relates to an experimental method for in-situ observation of inclusions in bearing steel molten steel. Including how to keep the sample from being polluted during melting, how to keep the sample from deforming, how to control the temperature, comprehensively observe the movement behavior of the inclusions in the high temperature molten steel, and keep the inclusions basically unchanged through extreme cold, and then under the electron microscope Observing the overall appearance of the inclusions and obtaining its composition through energy spectrum analysis realizes the in-situ observation of the behavior, overall appearance and composition of the inclusions. Background technique [0002] Harmful inclusions in steel have seriously affected the quality of steel. Controlling and removing harmful inclusions in steel to achieve clean steel smelting has becom...

Claims

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Application Information

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IPC IPC(8): G01Q30/02G01Q30/20
Inventor 徐迎铁陈兆平周灿栋王婷婷
Owner BAOSHAN IRON & STEEL CO LTD
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