A kind of hot-rolled strip steel for rake sheet and its production method and rake sheet processing method

Abstract

A hot-rolled steel strip for rake blades and its production method and rake blade treatment method, the chemical composition wt% is: C0.29-0.40%, Si0.1-0.40%, Mn1.1-1.7%, Cr0.10-0.80 %, Nb≤0.050%, V≤0.060%, Ti0.015~0.06%, B0.002~0.006%, N≤0.0070%, P≤0.020%, S≤0.015%, 4≤(Ti+Nb+V) / N≤20. Continuous casting and rolling is adopted, the furnace temperature of casting slab is >830°C, the heating temperature is 1100-1200°C, and the heat preservation is 1-4h; the rough rolling and finishing rolling temperature is 920-980°C. After finishing rolling, it is rapidly cooled at a cooling rate of 50-100°C / S to 550-650°C for coiling, and then slowly cooled with a cover for >48h. The heating temperature of the rake blank is 850-1000 ℃, and the heat preservation is 15-50 minutes; the temperature before quenching is ≥830 ℃, the oil quenching is 2-20 minutes, and the quenching oil temperature is ≤200 ℃; the tempering temperature is 200-300 ℃, and the heat preservation is 1-4 hours. The rake of the invention has a hardness of >53HRC, an impact power of >40J, good wear resistance and toughness, and a service life obviously higher than that of a 65Mn steel rake.

Description

technical field [0001] The invention belongs to the technical field of metallurgical technology, and particularly relates to a hot-rolled steel strip for rake blades with excellent wear resistance and toughness, a production method for the hot-rolled steel strip, and a processing method for rake blade blanks. Background technique [0002] At present, agricultural machinery accessories-rake blades are generally made of 65Mn high-quality carbon hot-rolled strip steel after shearing, oil quenching at 850°C-910°C, and tempering at 300°C-400°C. The main failure mode of the rake is wear and fracture. The wear resistance is mainly related to the hardness, and the fracture is mainly due to the impact of the hard soil or stones during the working process. Therefore, while the rake requires hardness, it must also have high toughness to resist large impact forces. Due to the high carbon content, the hardness of 65Mn steel after heat treatment is 38-45HRC, but this kind of high-carbon ...

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Problems solved by technology

Due to the high carbon content, the hardness of 65Mn steel after heat treatment is 38-45HRC, but this kind of high-carbon cutting tool steel is also high in brittleness and poor in plastic toughness, and the impact toughness after heat treatment is not higher than 5J

In large-scale agricultural operations, it is very difficult to replace rake blades after they break. Therefore, with the rapid development of agricultural mechanization at home and abroad, 65Mn rake blades can no longer meet the continuous operation requirements of large-scale agricultural machinery.

[0003] Papers such as "Research on As-Cast Microstructure and Wear Resistance of MO-Nb Bainite Steel" and "New Technology of Squeeze Casting of Ductile Iron Rake" and other papers introduce new material rakes directly formed by casting methods, and the casting process is complicated. Low production efficiency

[0004] The boron steel in "a boron-containing steel and its preparation method" provided by the patent publication number CN101148737A is a medium-carbon bar boron steel produced by electric furnace smelting, so it cannot be used to make rake blades

[0005] The boron-containing Q345B steel plate disclosed in the patent publication No. CN102080179A "A Manufacturing Method of Boron-Containing Structural Steel" has low carbon content, and the grain size is refined through controlled rolling technology to improve the strength of the hot-rolled plate, but the toughness and plasticity of the steel plate are poor. The formability is not good, and the patent does not mention the performance of the steel plate after heat treatment. According to the analysis, the carbon content of the steel plate is low, and the hardness after heat treatment is not enough, so it is not suitable for making rake blades

[0006] Patent "Carbon steel with excellent formability and its preparation method" (CN101346482A), the hot-rolled plate produced by reheating steel ingot is mainly bainite, and annealing treatment is required to ensure the toughness and plasticity of the steel plate, the production cost is high, and During smelting, it is required to precisely control the content of B and N before adding Ti element, which makes the smelting operation difficult

And the Mn content of the steel plate produced by this patent is 0.1-1.2%, the Mn content of the medium and low carbon steel is low, and the hardness after heat treatment is insufficient

[0007] The steel types mentioned in the above documents and patents are not suitable for the development requirements of the current harrow blade industry

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