Steel with excellent processing performance for gardening tool and production method thereof

Abstract

The invention discloses steel with excellent processing performances for a gardening tool and a production method thereof. The steel comprises the following components of, by weight, 0.45%-0.65% of C,0.1%-0.40% of Si, 0.5%-1.5% of Mn, 0.1%-0.5% of Cr, 0.02%-0.05% of Al, less than or equal to 0.4% of Ni, less than or equal to 0.5% of Cu, less than or equal to 0.020% of P, less than or equal to 0.010% of S and the balance Fe and inevitable impurities. The production method comprises the following steps that deoxidation is carried out by adopting Al, and time of argon blowing in tundish is larger than or equal to 10 minutes, the casting superheat degree is less than or equal to 25 DEG C, the thickness of a casting blank is 130-200 mm; charing temperature of the casting blank is larger than or equal to 500 DEG C; heating temperature is 1100-1200 DEG C, the temperature is kept for 2-5 hours, the rolling speed is 5-15 m per second, rolling start temperature is larger than or equal to 1080 DEG C, and rolling finish temperature is larger than or equal to 920 DEG C; and the cold speed is less than or equal to 20 DEG C per second, the casting blank is coiled at the temperature of 650-730 DEG C, then is put into a slow cooling pit for heat preservation and slow cooling for more than or equal to 48 hours, is cooled to below 200 DEG C, and then is air-cooled to the room temperature. According to steel with the excellent processing performances for the gardening tool and the production method thereof, the steel plate has excellent formability and wear resistance.

Description

technical field [0001] The invention relates to a hot-rolled coil and a production method thereof, in particular to a hot-rolled coil which is easy to process and produce gardening tools such as scissors and a production method thereof. Background technique [0002] At present, gardening tools such as scissors and shovels are mostly made of ordinary 50#, 55# and other medium carbon steels after forming and water quenching and tempering or SK5 and other high carbon steels after forming and oil quenching and tempering heat treatment. The high carbon hot rolled plate has high strength, The hardness is high, the yield strength ratio is generally more than 70%, the processing and forming is difficult, and heat treatment is easy to crack; 50#, 55# and other medium carbon steels have high hardness, the yield strength ratio is generally more than 60%, and there is heat treatment Insufficient hardness and poor wear resistance. In order to meet the needs of users, it is urgent to dev...

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Problems solved by technology

[0003] Yan Jun, Cen Qihong, Jiang Yehua, and Zhou Rong disclosed a high-boron medium-carbon alloy tool steel in the paper "As-Cast Microstructure of High-boron Medium-Carbon Alloy Tool Steel" published in "Material Engineering" Issue 6, 2013. The boron content is 1.5% to 2.5%. The boron content in the steel is too high. The macroscopic hardness of the matrix in the as-cast state reaches 55HRC. The hardness is too high and it is difficult to process and form.

[0004] The patent application No. 201510687941.1 discloses an alloy tool steel and its production method, involving a medium carbon tool steel, the steel contains: C 0.5%, Si 0.2%, Mn 0.5%, Cr 5.0%, Mo 2.3%, V 0.5%, S ≤ 0.003%, P ≤ 0.02%, the alloy tool steel is added more Cr, Mo, V and other alloys, the cost is high, and the hardness is high, it is not suitable for processing and manufacturing various gardening with complex shapes tool

[0005] The patent application number 201510174384.3 discloses a method for producing thin-gauge tool steel with a CSP line without spheroidizing annealing. The patent application number 201510174503.5 discloses a production method of tool steel that can be directly cold-rolled. The above two patents The descriptions all adopt the production process of low-temperature rolling, coiling and then tempering. After the steel plate is rolled, low-temperature coiling close to the martensitic transformation temperature is adopted. On the one hand, it requires extremely high coiler capacity; Precisely control the temperature zone. If the temperature control is not precise, martensitic phase transformation will occur, and the tape will be easily broken during the coiling process. After coiling, high temperature tempering treatment is required, and the cost is high.

[0006] And the patent application number 201510174384.3 discloses a method for producing thin-gauge tool steel with a CSP line without spheroidizing annealing, which involves a production method of thin tool steel plates with a thickness of 1-2.5 mm, which cannot meet the requirements of thick-gauge tool steel plates. usage requirements

[0007] The patent application number 201510025621.X discloses a steel 55MnB for household gardening tools and its preparation method. The thickness of the steel plate described in it is only 3-5 mm, and the application range is limited, which cannot meet the needs of thinner or thicker specifications.

Steel contains: C0.52%~0.60%, Si 0.15%~0.35%, Mn 0.7%~1.00%, S≤0.008%, P≤0.025%, Als 0.010%~0.060%, B 0.0005%~0.0030%, This patent adopts boron-containing composition design, but does not emphasize the control of oxygen and nitrogen. Boron in molten steel is easy to combine with oxygen and nitrogen to form compounds, which not only weakens the effect of solid solution boron on improving hardenability, but also, The compound phase of B and N is easy to segregate into a network at the grain boundary, resulting in boron brittleness, resulting in defects such as high brittleness

The thermal deformation resistance of boron-containing steel is high, the hot-rolled plate shape is difficult to control, the hot-rolled plate shape is poor, and the subsequent heat treatment process is also difficult to level, which seriously affects the quality of the finished product

On the other hand, the yield strength of the steel plate described in this patent is 390-470MPa, the tensile strength is 750-820MPa, and the elongation is 17%-26%. The strength is still high, and there are still certain difficulties in processing.

And the described production process adopts high temperature coiling at 750°C, the surface of the steel plate is seriously decarburized, the surface oxide scale is thicker, and the user has a large amount of grinding, which affects the production efficiency

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