Working roller for wire and bar roughing mill stand and manufacturing method thereof

Abstract

The invention discloses a working roller for a wire and bar roughing mill stand. The working roller comprises, by weight, 2.9-3.6% of C, 1.2-2.0% of Si, 0.3-0.8% of Mn, 0.2-1.0% of Cr, 1.0-2.0% of Ni,0.2-0.5% of Mo, less than or equal to 0.15% of P, less than or equal to 0.3% of S, and the balance being Fe and inevitable impurities. A manufacturing method is characterized in that a pearlitic ductile cast iron blank manufactured through integral casting is subjected to rough machining and then quenching heat treatment to obtain the working roller with the structure of bainite, tempered sorbiteand carbide for the roughing mill stand. The pearlitic ductile cast iron blank manufactured through integral casting is subjected to rough machining and then quenching heat treatment, so that not only is the hardness drop inside and outside a working layer reduced, but also the wear resistance is improved, and the probability of occurrence of hot cracks at the bottom of a roller groove is reduced.

Description

technical field [0001] The invention relates to a work roll for a wire and bar rough rolling stand and a manufacturing method thereof, belonging to the technical field of steel rolling. Background technique [0002] In recent years, with the development of high-speed and continuous rolling of wire and bar mills at home and abroad, and the continuous improvement of rolled materials, steel mills have higher and higher requirements for roll applicability. The rough rolling stand has the characteristics of high rolling temperature, low rolling speed and large reduction. Especially in recent years, the length of the rolled material is long and the rough rolling roll is heated for a long time. Therefore, it is not only required that the roll has good wear resistance and high strength. , but also have better thermal crack resistance and toughness. At present, the traditional pearlitic ductile iron rolls are generally used for the rough rolling stand of wire and bar. The following ...

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Problems solved by technology

[0003] 1. The internal and external performance of the working layer of the roll is quite different. The traditional pearlitic ductile iron roll generally adopts the method of integral casting. The prepared pearlitic ductile iron roll has a very large difference in hardness inside and outside the working layer, and the hardness drop between the inside and outside of the working layer of 100mm can reach 10HSD, leading to a significant decrease in the wear resistance of the roll during use, and the online rolling use time is short, which affects the rolling efficiency

[0004] 2. Pearlitic ductile iron rolls have poor wear resistance, resulting in poor thermal crack resistance, severe thermal cracks at the bottom of the groove, low single rolling volume and affecting rolling quality

Due to the high rolling temperature and slow rolling speed of the roughing stand, the surface temperature of the roll body is high, the matrix of pearlitic ductile iron products is mainly pearlite, and the matrix strength is low. Under the continuous impact of the billet, the bottom of the roll groove is prone to heat Cracks can not maintain a good pass shape, resulting in the failure to ensure a good material shape after rough rolling, affecting the quality of subsequent rolling

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