Development And Making Of Roll Ring For High Speed Wire Mill

With the appearance of advanced roll ring mills and effective roll ringing techniques, the roll ringing industry has made a rapid development. At the same time, the manufacturing of roll ring is accelerated to stride into the new technique field. How to elevate the roll ringing life and quality to suit the mills is a new question for discussion for the persons who develop roll rings. During the recent years the breakthrough of manufacturing the new type of roll ring has been made. It is possible for the roll ring of high Cr cast iron widely used at present to be replaced by the roll ring of high speed steel (HSS) in the ten years. The composite roll ring of high speed steel has the synthetical life of over ten times more than traditional high Cr cast iron roll ring.In this thesis, at first the chemical composition of high speed steel for roll ring has been designed. Then the microstructure, heat treatment and performance of high speed steel are studied systematically by using metallograph, XRD, SEM and EDS. The high speed steel of roll ring has character of high carbon and high alloy elements. So it is easy to form a lot of netlike carbides. These carbides can depress the properties of high speed steel. It is pivotal to improve the formation and distribution of carbides in the solidification microstructure of composite roll rings of high speed steel. So the influence of modification with RE, Ti, RE-Ti-Mg on high speed steel of composite roll ring upon microstructure is investigated emphatically. What's more the bi-metallic centrifugal cast and machining have been analyzed.The results show that the unmodified samples have coarse grain which is mainly from 80~120μm and carbides network which is from 30 to 60μm. The solidification microstructure of HSS is refined lightly when modified with 0.3% RE; when modified with 1.0%Ti the solidification cell structure which is mainly from 20 to 60μm and carbides network which is from 10 to 40μm are refined evidently. When modified with the 1.4%RE-Ti-Mg compound, the solidification structure was improved so evidently that most of carbides network is discontinuous. The cell structure is mainly from 10 to 50μm and carbides network which is from 10 to 20μm.The element of Ti in the alterative and the carbon in the liquid of steel can create a lot of dispersive particles of TiC at the high temperature during the solidification by the analysis of SEM and EDS. The particles of TiC can accelerate the formation of MC...