Development And Production Quality Control Of High - Boron High Speed ​​Steel Centrifugal Roll In Kunshan Steel Wire

With the progress of the steel industry, the need of the high-performance surge for modern roller mill is significantly increased, the traditional high chromium cast iron roll rolling performance does not meet the requirements. Compared to the foreign technology, domestic roll technology and production capacity are still not high, high-performance roller is also dependent on imports, and the main factors restricting the development of high-performance roll are material and roll manufacturing technology. Therefore we have to study the roll materials and develop the new roll manufacture technology.In this project, according to the requirement of the rod/wire fine roll in Kunming Steel Group, We choose the high B high speed steel materials, and designed the component C0.40～0.55%, Si0.50～0.70%, Mn0.50～0.80%, Cr4.5～5.0%, Mol.80 ～2.20%, W0.8～1.2%, B1.2～1.8%, V0.4～0.8%, P<0.05% and the S<0.05%. High boron high speed steel roll material, has a long service life, good casting properties and hardenability, good hardenability, red hardness and good abrasion resistance and low cost.Ordinary centrifugal composite casting method was used to product high-speed boron steel roll, three-layer composite method product high boron high speed steel composite roll, in order to prevent the outer layer of boron into the core to reduce the performance of roll, transition layer was added between the barrel and the core layer. First of all, which is to pour high boron high speed steel water in the working layer, and then continue centrifugal ductile cast iron transition layer, and finally in the casting pit under static cast ductile iron core, high boron metallurgical combine high speed steel composite roll were successfully obtained. Medium frequency induction melting furnace was used to melt high boron high speed steel alloys, rare earth compound modifier in the ladle into law by modification, baked temperature was controlled at 1580℃. The centrifugal casting process parameters:temperature of the outer casting is 1450℃, the rotation time is 8 minutes; buffer layer pouring temperature is 1420℃, the rotation time is 7 minutes; core pouring temperature is 1360℃.The heat treatment of high boron high speed steel roll,especially focusing on the influence of quenching and tempering temperature on the microstructure and properties. The microstructure of high boron high speed steel roll shows that the high-speed steel roll boron cast is consisted by the martensitic matrix, residual austenite and boron carbide; After quenching, most of the matrix microstructure is martensite, and a large number of granular and short rod carbon boron compounds precipitate along the grain boundaries, and the network distribution is formed; After tempering, the martensite transformation is tempered martensite, and the microstructure of the two carbides is the highest. Boron high speed steel composite roll suitable quenching temperature is 1050℃, tempering temperature is 500℃, heat the matrix dispersed a large number of small boron carbide and carbide network organization basically eliminated; tempering after hardness up HS83, toughness 12J/ cm2, the requirements to achieve the desired depth of hardened layer 80mm high speed steel rolls boron.The manufacture high boron High speed steel centrifugal composite roll is a systematic engineering, many process as long as there is a link of improper operation may lead casting defects and cause of waste. Knowledge of quality management is applied in this paper, analysis of the poor quality of the air hole inclusion and fusion in high boron high speed steel roll with quality management tool, to develop quality control measures, improve the optimized production technology, perfect quality management system, ensure the quality of the roll.