H13热作模具钢电渣重熔渣系优化

 模具钢是模具最重要的组成部分,其品种、规格、质量对模具的性能、使用寿命和制造周期起着决定性作用。因为模具钢苛刻的质量要求,对模具钢生产技术及制备过程提出了更高要求。电渣重熔(ESR,electroslag remelting)工艺冶炼出的钢锭具有高均匀度、高洁净度、低偏析度等优势,逐渐成为冶炼优质模具钢的主要技术手段。在电渣重熔生产过程中,电渣渣系起着熔化电极、钢水精炼、凝固结晶等主要作用,是熔炼稳定的基础,因此,选择合适的渣系成分及性能是电渣重熔工艺的关键。结合4Cr5MoSiV1热作模具钢特性,以某钢厂现行5种H13热作模具钢ESR渣系为研究对象,通过渣系物化性能分析和微观结构模拟研究,提出了渣系优化方向,确定了适合电渣重熔H13热作模具钢的渣系。结果表明,L4渣系的熔点、黏度、密度、光学碱度、电导率等物理化学性能较好。该熔渣铝的平均配位数最大,为2.39,且三配位和四配位的铝所占比例较高,网络结构较为复杂;复杂结构单元Q3和Q4含量最多,具有高聚合度的网络结构;Al—O键长较短且存在键长更短的Si—O、Si—F键,电渣重熔过程的稳定性最强,采用该渣系能够有效提高H13热作模具钢组织性能、表面质量和降低电耗。研究结果为某钢厂H13热作模具钢电渣重熔工业生产提供了理论指导。

Optimization of electroslag remelting slag system of H13 hot work die steel

Die steel is the most important part of mold, its variety, specifications and quality play a decisive role in the performance, service life and manufacturing cycle of the mold. Due to the strict quality requirements of die steel, higher requirements are put forward on the production technology and preparation process of die steel. The steel ingot smelted by the electroslag remelting (ESR) process has the advantages of high uniformity, high cleanliness and low segregation, gradually become one of the main technical means for smelting high-quality die steel. During electroslag remelting, the slag system plays a key role in melting electrodes, molten steel refining, solidification and crystallization, etc, it is the basis of smelting stability, therefore, selecting appropriate slag composition and performance is the key to the electroslag remelting process. This research combined the characteristics of 4Cr5MoSiV1 hot work die steel, take the current five H13 hot work die steel ESR slag systems of a steel factory as the research object, through the physical and chemical performance analysis and microstructure research of the slag systems, the direction of slag system optimization was put forward, then defined the slag systems suitable for ESR remelting H13 hot work die steel. The results shows that the melting point, viscosity, density, optical alkalinity, electrical conductivity and other physical and chemical properties of L4 slag system is better. The average coordination number of Al in the slag is the largest while it is 2.39. Moreover, the proportion of Al with three coordination and four coordination is relatively high, and the network structure is more complicated. Complex structural units Q3 and Q4 have the most content, and they have a network structure with high polymerization degree. Al—O bond length is short and Si—O, Si—F bonds with shorter bond lengths, electroslag remelting process is the most stable, using this slag system can effectively improve the structure and performance, surface quality of H13 steel, and reduce power consumption. The research results provide theoretical guidance for the industrial production of H13 hot work die steel electroslag remelting in a steel factory.