How to solve the cold heading crack of electrical pure iron
The most common quality problem when users use pure iron is cold heading cracking, and the causes of cracking can be roughly divided into internal quality problems of wire rod, surface quality problems of wire rod and improper deep processing technology of users, of which the first two categories account for the vast majority. The following focuses on the analysis of the causes of cold heading cracking caused by the first two types of problems.In the eyes of peers, Cathode Flat It has good qualities that people covet, and it also has many loyal fans that people envy. https://www.slhpureiron.net
The internal quality problems of wire rod are mainly caused by inclusions, and the general slag inclusion is caused by slag entrapment during continuous casting. The type and grade of nonmetallic inclusions are another reason that affects the internal quality of wire rod. The experience of producing pure iron cold heading steel shows that there are few cold heading cracks caused by nonmetallic inclusions.
Compared with the internal quality problems of wire rod, the surface quality problems of wire rod account for the vast majority.
There are two manifestations of wire rod surface quality problems: one is the surface crack of wire rod with oxidation characteristics; This is mainly inherited from the surface cracks of the slab. Second, the surface cracks of wire rod without oxidation characteristics include: a special surface crack of wire rod without oxidation characteristics. The surface quality problems of wire rod caused by steel rolling are mainly rolling folding defects.
Measures taken:
First, steelmaking and continuous casting
Because the liquid level fluctuation is controlled within 20 mm, the depth of slag inclusion under the skin will be less than 2mm, so the liquid level fluctuation is controlled within 15 mm; If the depth of subcutaneous slag inclusion is less than 2mm, it can be eliminated when it is heated in the furnace. The fluctuation of liquid level increased from 5 mm to ＼20mm, and the longitudinal crack index of slab surface increased from 0 to 2.0. Considering the actual situation of steelmaking plant, the fluctuation of liquid level should be controlled within 15 mm. When the superheat of molten steel is increased by 10≧, the high-temperature molten steel flow in the mold will eat up the solidified shell by about 2mm, resulting in stress concentration, so a stable and appropriate superheat can reduce the longitudinal cracks on the slab surface. Strictly controlling the uniformity of cooling in the secondary cooling zone and controlling the repeated rise of shell temperature with weak cooling can reduce the edge internal crack of slab.
Second, steel rolling
The measures taken are as follows: When cold heading steel is rolled, check and replace the guide device, guide wheel and jacketing roller frequently; According to the cold heading steel wire rod rolling, reasonably adjust the roughing pass system, optimize the setting of finishing mill and reducing sizing mill, improve the process parameters, strictly control the rolling temperature, and delay the cooling after rolling to greatly improve the product quality.
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