ABSTRACT

Directional solidification experiments were carried out on peritectic steels to investigate the microstructure and volume shrinkage. A δ-dendritic structure developed intermittently and was enclosed by γ-austenite at growth rates of 15, 50, and 80 μm s⁻¹. The primary dendritic spacing narrowed and the average spacing of dendrites decreased as the growth velocity increased. The functional relationship between the secondary dendrite arm spacing and cooling rates was established by statistical analysis. The influence of cooling rate on crack formation was analysed as a function of volume shrinkage. Reducing the cooling rate of the solidification delayed a massive type of peritectic transformation away from the ZST–ZDT brittle zone, thus reducing the probability of crack formation.

摘要

在包晶钢上进行定向凝固实验，以研究其显微组织和体积收缩率。甲δ -dendritic结构发达间歇地由封入γ在15，50的增长率-austenite，和80μm的小号^-1。随着生长速度的增加，初级树突间距变窄，树突的平均间距减小。通过统计分析建立了二次枝晶臂间距与冷却速率之间的函数关系。分析了冷却速率对裂纹形成的影响，该影响是体积收缩的函数。降低凝固的冷却速率会延迟大量的包晶转变，使其远离ZST-ZDT脆性区，从而降低了裂纹形成的可能性。