Na<sub>2</sub>O对超高碱度连铸保护渣性能的影响

doi:10.13228/j.boyuan.issn0449-749x.20210391

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Abstract During the continuous casting of peritectic steel, defects of longitudinal cracks of casting strands frequently appear. Production practice shows that mold fluxes with strong crystallinity can effectively reduce the occurrence of longitudinal cracks, but it will deteriorate the lubrication function of mold fluxes. In recent years, the ultra-high basicity continuous casting mold fluxes have the characteristics of low initial crystallization temperature and fast crystallization rate, which can successfully balance the contradiction between lubrication and heat transfer in the continuous casting of peritectic steel. However, there are few studies on the effects of related components on the crystallization properties of the ultrahigh basicity mold slag, and the corresponding structural characteristics are also rarely reported. Na₂O is a common component element in mold fluxes and plays an important role in adjusting the properties of mold fluxes. The effect and mechanism of Na₂O content on the melting flow characteristics and solidification and crystallization properties of continuous casting mold fluxes at ultra-high basicity(R=1.75) was analyzed by hemispherical point melting temperature tester, rotational viscometer and high temperature in-situ crystallization performance tester. The results showed that the viscosity (1 300 ℃) of mold fluxes,melting temperature,break temperature and crystallization temperature all decreased with the increase of Na₂O content,while the crystallization rate first decreased and then increased,and the crystallization rate was the lowest when mass percent of Na₂O was 6%. In addition,it is found that the main precipitates in the ultra-high basicity mold flux were gun spar(Ca₄Si₂F₂O₇). With the further increase of Na₂O content,the new crystalline phases CaF₂ and Na₂CaSiO₄F appeared in the mold flux.

Key words： mold flux Na₂O ultra-high basicity break temperature crystallization property

Received: 09 July 2021

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	PAN Wei-jie
	LI Min
	ZHU Li-long
	HE Sheng-ping

Cite this article:

PAN Wei-jie,LI Min,ZHU Li-long等. Effect of Na₂O on properties of ultra-high basicity continuous casting mold fluxes[J]. Iron and Steel, 2022, 57(1): 93-101.

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http://www.chinamet.cn/Jweb_gt/EN/10.13228/j.boyuan.issn0449-749x.20210391 OR http://www.chinamet.cn/Jweb_gt/EN/Y2022/V57/I1/93

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