Harrow disc strip steel and production method and harrow disc heat treatment method

Abstract

The present invention discloses harrow disc strip steel and a production method and a harrow disc heat treatment method, the harrow disc strip steel comprises the following chemical components: 0.27-0.37wt% of C, 0.1-0.40wt% of Si, 1.1-1.7wt% of Mn, 0.002-0.006wt% of B, 0.10-0.80wt% of Cr, 0.01-0.050wt% of Al, less than or equal to 0.1wt% of Ti, less than or equal to 0.1wt% of V, less than or equal to 0.0070wt% of N, less than or equal to 0.020wt% of P, less than or equal to 0.010wt% of S, and balance of Fe and impurities. Continuous casting and continuous rolling are used, the casting blank in-furnace temperature is greater than 830 DEG C, heating temperature is 1100-1200 DEG C, heat preservation is performed for 1-2h; and rough rolling finishing rolling temperature is 920-980 DEG C. After finishing rolling, the casting blank is cooled to 500-600 DEG C in the cooling rate of 30-80 DEG C / S, then winded, covered, and slowly cooled for more than 48h. Harrow blank heating temperature is 830-950 DEG C, heat preservation is performed for 15-40min; before-quenching temperature is greater than or equal to 820 DEG C, oil quenching is performed for 15-40min, the quenching oil discharge temperature is less than or equal to 200 DEG C; tempering temperature is 200 to 300 DEG C, and heat preservation is performed for 1-4h. The harrow disc hardness is greater than 50HRC, impact energy is greater than 27J, the harrow disc has good abrasion resistance and toughness and plasticity, the largest hot pressing radian is 60 degrees, and the service life is significantly higher than that of 65Mn harrow disc.

Description

technical field [0001] The invention belongs to the technical field of metallurgical technology, and in particular relates to a special hot-rolled steel strip suitable for making agricultural machinery accessories, a production method of the hot-rolled steel strip, and a heat treatment method for a rough rake. Background technique [0002] 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. 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. 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] Patent Publication No. CN85100775A provides a "new spring steel 28 manganese silicon boron steel for manufacturing automobile leaf springs", which is a steel with high Si content, high production cost, high Si content, and many inclusions in the steel, which affect toughness, plasticity and fatigue performance

[0005] 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

[0006] 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. 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

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