Improvement of Toughness and Wear Resistivity of High Chromium Cast Irons for Hot Working Rolls by Control of Solidification Structure

凝固组织控制提高热加工轧辊用高铬铸铁的韧性和耐磨性

基本信息

批准号：
03650550
负责人：
IKEDA Minoru
金额：
$ 1.15万
依托单位：
UNIVERSITY OF TOKYO
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Rolling technologies of steels today have been developed to save energy and to provide high quality products. Rolling conditions have become much severer and this has resulted in strong demands for improving qualities of rolls, especially their durability. Many types of rolls have been developed in response to this request.High chromium cast irons have been widely used as hot working rolls. The most significant reason for the good wear resistance of these cast irons is the presence of hard chromium carbides embedded in a matrix of martensite or austenite. Carbides in the microstructure, depending on their type, morphology and volume fraction, provide the hardness required for application without degradation. Addition of molybdenum in high chromium cast irons causes the formation of Mo_2C which crystallize in finely dispersed form as an eutectic at a final stage of solidification. These finely dispersed Mo_2C carbides bring about very good resistivity for high temperature rolling wear.In the present paper, by adding molybdenum up to 10 mass% in 20 mass% Cr cast irons, microstructure, solidification and transformation behaviors, mechanical properties and wear characteristics were discussed. Mo_2C was formed as an eutectic at a final stage of solidification of high Cr cast iron containing Mo. These finely dispersed carbides which are harder than Cr_7C_3 are expected to give good wear resistivity of hot rolls. The effect of addition of Mo up to 10 mass% in 3 mass% C-20 mass% Cr irons are investigated. With increasing Mo content, tensile strength and fracture toughness decrease monotonically, and hot wear resistivity increases. These effects can be explained by the amount of Mo_2C. Fine carbides of Mo_2C provide crack initiation and growth sites to cause fracture. However they can prevent the propagation of wear cracks. Eutectic carbides should be controlled within about 35 vol% considering a balance between mechanical properties and wear resistivity.

如今，已经开发出钢的滚动技术来节省能源并提供高质量的产品。滚动条件已经变得更加严重，这导致对提高卷的质量，尤其是其耐用性的强烈要求。为了响应此请求，已经开发了许多类型的卷。高铬铸铁已被广泛用作热工作卷。这些铸铁的耐磨性良好的最重要原因是存在嵌入在马氏体或奥氏体基质中的硬铬碳化物。微观结构中的碳化物，取决于其类型，形态和体积分数，提供了无降解所需的硬度。在高铬铸铁中添加钼会导致MO_2C的形成，该形成在凝固的最后阶段以精美的形式结晶为共晶。这些分散的MO_2C碳化物对高温滚动磨损产生了非常好的电阻率。在当前纸中，讨论了20个质量％CR铸铁，微结构，固化和转化行为，机械性能和磨损特性中的钼量高达10质量％。 MO_2C在固定含有MO的高CR铸铁的最后阶段形成了Eutectic。这些分散的碳化物比CR_7C_3更难，预计将具有良好的热卷磨损电阻率。研究了3个质量％c-20质量％cr ron的MO添加高达10个质量％的影响。随着MO含量的增加，拉伸强度和断裂韧性单调降低，热磨损电阻率增加。这些效果可以用MO_2C的量来解释。 MO_2C的细碳纤维提供裂纹的启动和生长位点，以引起断裂。但是它们可以防止磨损裂纹的传播。考虑机械性能和磨损电阻率之间的平衡，应在约35卷中控制共晶碳酸盐。