N08810耐蚀合金200 mm厚连铸板坯纵向裂纹形成机理的分析

通过光学、扫描电子显微镜、能谱仪和G1eeble-3800热模拟试验机对1流立式连铸机生产的UNSN08810合金(/%:0.06C、0.45Si、0.92Mn、0.016P、0.001S、30.15Ni、19.80Cr、47.81Fe、0.33Ti、0.23Al、0.014 0N)200 mm×1 300 mm连铸坯的纵向裂纹进行了分析。结果表明,纵向裂纹沿粗大的柱状晶晶界向铸坯内部扩展、裂纹深度为18～20 mm。高温塑性试验得出,当温度≥1100℃时合金的断面收缩率急剧下降。分析表明,凝固初期柱状晶之间连接比较薄弱,易在晶界处开裂,加上晶界处脆性相TiC的析出,造成应力集中,并使裂纹更容易延晶界扩散,最终形成纵向裂纹。

An Analysis on Forming Mechanism of Longitudinal Crack of N08810 Corrosion Resistant Alloy 200 mm Thickness Casting Slab

An analysis on longitudinal crack of 200 mm×1 300 mm casting slab of UNS N08810 alloy(/%:0.06C, 0.45Si,0.92Mn,0.016P,0.001S,30.15Ni,19.80Cr,47.81Fe,0.33Ti,0.23Al,0.0140N) produced by one-strand vertical continuous casting machine has been carried out by optical,scanning electron microscope,energy dispersive spectrometer and Gleeble-3800 thermal simulation machine.Results show that the longitudinal crack extends along grain boundary of coarse columnar crystal towards inner casting slab,the depth of crack is 18～20 mm.Test of high temperature plasticity of allov obtains that as temperature≥1100℃the reduction of area of alloy dramatically decreases.And the analysis indicates that at early period of solidification the connection between columnar dendrites is weak,the boundary of columnar crystal easily cracks,in addition the brittle phase TiC deposits at grain boundary lead to stress concentration,the crack easily extends along grain boundary to form the longitudinal crack finally.