Quantitative evaluation method for precipitation velocity of hypereutectoid steel network cementite

A technology of hypereutectoid steel and quantitative evaluation, which is applied in the direction of material analysis, measuring device, and material analysis by optical means, which can solve the problems such as the change of the precipitation speed of the reticulated cementite of the wire rod, etc., to prevent cooling. The effect of excessive speed

Pending Publication Date: 2021-11-16
ANGANG STEEL CO LTD
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  • Application Information

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Problems solved by technology

[0005] The above-mentioned patent introduces the inspection and evaluation method of wire rod network cementite, but it does not clarify the change of wire rod network cementite precipitation speed during the cooling process

Method used

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  • Quantitative evaluation method for precipitation velocity of hypereutectoid steel network cementite
  • Quantitative evaluation method for precipitation velocity of hypereutectoid steel network cementite
  • Quantitative evaluation method for precipitation velocity of hypereutectoid steel network cementite

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Experimental program
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preparation example Construction

[0025] 1) Preparation of thermal simulation samples: Hypereutectoid steel is smelted in a 200kg vacuum furnace, and then the steel ingot is heated to 1050°C-1100°C, kept for 30min-40min, rolled into a 20mm-30mm thick steel plate, and wire-cut The method is prepared on the steel plate thermal simulation samples.

[0026] 2) Heat the thermal simulation sample to a temperature of 850°C-950°C and keep it warm for 8min-15min. Cool the sample to the set temperature at a cooling rate of 0.1°C / s-5°C / s, and then cool it to room temperature at a cooling rate of 20°C / s-25°C / s;

[0027] 3) After the sample is inlaid, ground, and polished, it is corroded with 5% nitric acid alcohol solution; the corroded metallographic sample is observed with an optical microscope: the sample is initially observed at a magnification of 200-1000 times, Determine the area where the network cementite precipitation is the most serious, as the field of view for the evaluation of the sample network cementite;...

Embodiment

[0034] The chemical composition of the sample is calculated by weight percentage as C 0.96%; Si 0.22%; Mn 0.65%; Cr 0.15%; the rest is Fe and unavoidable impurities. The sample size is

[0035] Heat the hypereutectoid steel sample with the above chemical composition to 900°C at a rate of 10°C / s, and keep it for 10 minutes to make it fully austenitized.

[0036] After the samples were austenitized, the four samples were cooled to 850°C, 750°C, 650°C, and 550°C, respectively, at a cooling rate of 0.5°C / s. After the sample is cooled to the set temperature, it is then cooled to room temperature at a cooling rate of 20°C / s.

[0037] After mounting, grinding and polishing the sample, it was corroded with 5% nitric acid alcohol solution. The corroded metallographic samples were observed with an optical microscope. Preliminarily observe the sample at a magnification of 500 times to determine the area where the precipitation of reticulated cementite is the most serious, as the fie...

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Abstract

The invention relates to a quantitative evaluation method for precipitation velocity of hypereutectoid steel network cementite, which comprises the following steps: heating a thermal simulation sample to 850-950 DEG C, and preserving heat; cooling the sample to a set temperature, and then cooling to room temperature; inlaying, grinding and polishing the sample, and corroding the sample by using a 5% nitric acid alcohol solution; observing the corroded metallographic specimen by using an optical microscope; evaluating the cementite grade L of the metallographic specimen; evaluating the grade of network cementite; and calculating the cementite precipitation speed in the set temperature interval. The method has the advantages that the temperature of the wire rod quickly passes through the interval, and precipitation of network cementite is inhibited. Meanwhile, the cooling speed of the wire rod in other temperature intervals can be properly reduced, and the situation that the subsequent wire rod drawing performance is affected due to the fact that the tensile strength of the wire rod is too high due to the too high cooling speed is prevented.

Description

technical field [0001] The invention relates to a quantitative evaluation method for the precipitation speed of reticular cementite in hypereutectoid steel. Background technique [0002] High carbon steel wire rod is an important raw material widely used in automobiles, railways, bridges and other fields. High carbon steel wire rod is generally drawn to form the final product. In the wire rod drawing process, non-metallic inclusions in the steel, hard and brittle precipitation and other internal defects in the wire rod will increase the broken wire rate in the wire rod drawing process, which not only reduces the production efficiency of the user, but also makes the wire rod system The resulting steel wire produces internal defects and reduces the service life of the product. [0003] The cementite inside the high carbon steel wire rod is a hard and brittle precipitated phase, especially the reticular cementite precipitated along the original austenite grain boundary of the...

Claims

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Application Information

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IPC IPC(8): G01N21/84G01N25/00G01N1/32G01N1/28
CPCG01N21/84G01N25/00G01N1/28G01N1/32
Inventor 郭大勇高航车安张皓星张俊峰王宏亮王秉喜潘阳张博马立国
Owner ANGANG STEEL CO LTD
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