The typical specification characteristics of section steel universal edging roll and special-shaped steel s-roll products are that the roll neck at the operation end is slender. Because of the roll body processing pass, the semi steel material is generally selected. Affected by the semi steel material, the solidification and crystallization range is wide, which is easy to form loose defects. In serious cases, the roll neck fracture accident can be caused, which affects the safety of use. Therefore, the solidification quality of the roll neck must be guaranteed, The structure of the product roll neck is shown in the figure.
Combined with the production situation and product quality characteristics, a gradient riser production process is designed to improve the feeding efficiency, reduce the riser diameter and improve the net to gross ratio of the product.
The typical specification of the high carbon steel roll casting studied is that the roll neck at the operating end is long and thin. In order to ensure the quality of the roll body and feeding effect, according to the feeding principle, the solidification time of the riser should not be less than the solidification time of the part being fed. The riser size should be designed according to the diameter of the roll body. In order to ensure the position feeding of the roll body, the riser size is generally larger, Therefore, the machining allowance of the shaft neck of the semi steel thin roll neck product in the riser part is large, and the area with good solidification quality of the outer layer is removed, and the remaining core part with coarse structure and shrinkage porosity is retained in the finished roll neck.
High carbon steel roll castings are made of semi steel and high carbon semi steel, and the carbon content ranges from 1.60% to 2.30%. It can be seen from the iron carbon phase diagram (see Fig. 2) that for the materials with carbon in this range, the crystallization range is the widest. In the later stage of solidification, with the decrease of molten steel temperature, the fluidity becomes poor, the dendrite bridging is formed in molten steel, and the central axis is easy to be loose.
(1) through the analysis of product defects, combined with the theoretical knowledge of casting, a gradient riser process combining electric heating and insulating refractory was designed to provide technical support for the production of high carbon steel roll casting.
(2) the gradient riser process can improve the quality of the high carbon steel roll casting, reduce the loose defects and meet the user’s performance.