电渣重熔-等离子旋转电极雾化制备高品质316H奥氏体不锈钢粉末

Preparation of high-quality 316H austenitic stainless steel powder by electroslag remelting-plasma rotating electrode atomization

首先采用电渣重熔法熔炼316H奥氏体不锈钢母合金,随后采用等离子旋转电极雾化(PREP)法制备了球形316H奥氏体不锈钢粉末。利用氧氮分析仪、扫描电镜(SEM)、X射线衍射仪(XRD)、霍尔流速计和激光粒度分布仪等研究了粉末的氧含量、形貌、相结构、流动性、松装密度、振实密度及粒度分布。结果表明:电渣重熔制备的316H奥氏体不锈钢母合金全氧含量为20×10^(-6),铸锭成分均匀;等离子旋转电极雾化法制备的316H奥氏体不锈钢粉末全氧含量为70×10^(-6),粉末粒度呈现双峰分布,细粉收得率高,粒径为15~150μm的粉末占比近80%,粉末粒径分布范围广、球形度高、卫星粉少。粉末表面基本为胞状晶,截面为均匀的枝晶组织,为单一的γ-Fe相结构。制备态粉末的霍尔流速、松装密度和振实密度分别为14.83 s·50^(-1)g^(-1)、4.725 g·cm^(-3)和5.401 g·cm^(-3)。粗粉和细粉质量分数各占一半时,粉末的霍尔流速为12.91 s·50^(-1)g^(-1),小于初始粉末的霍尔流速,提高了粉末的流动性能。长时间的真空储存能降低粉末的带电性能,进而降低粉末颗粒之间排斥作用,可进一步提高粉末流动性。粗、细粉之比为7:3时,粉末的填充性能最好,填充率高达70.6%。

Firstly,316H austenitic stainless steel ingot was prepared by electroslag remelting,and then spherical 316H austenitic stainless steel powder was prepared by plasma rotating electrode atomization(PREP).Oxygen content,morphology,phase structure,flow-ability,apparent density,tap density and particle size distribution of the powders were studied by means of oxygen nitrogen analyzer,scanning electron microscopy(SEM),X-ray diffraction(XRD)analysis,hall flow meter and laser particle size analyzer.The results show that the total oxygen content of the 316H austenitic stainless steel ingot prepared by electroslag remelting is 20×10^(-6),and the composition of the ingot is uniform.The total oxygen content of the 316H austenitic stainless steel powder prepared by plasma rotating electrode atomization is 70×10^(-6),the particle size presents bimodal distribution,the yield of fine powder is high,the proportion of the powder with particle size in the range of 15^(-1)50μm is nearly 80%,and the powder has a wide range of particle size distribution,high sphericity and less satellite powder.The surface of the powder is cellular crystal and the cross section is uniform dendrite structure,and the structure is singleγ-Fe phase structure.The hall flow-ability,apparent density and tap density of the as prepared powders are 14.83 s·50^(-1) g^(-1),4.725 g·cm^(-3) and 5.401 g·cm^(-3),respectively.When the mass fraction of the coarse powder and the fine powder is half respectively,the hall flow-ability of the powder is 12.91 s·50^(-1) g^(-1),which is less than that of the as prepared powder,and the flow-ability of the powder is improved.Long time vacuum storage can reduce the electrically charge property of the powder,and then reduce the repulsion between powder particles,and further improve the powder flow-ability.When the ratio of coarse powder to fine powder is 7:3,the filling performance of the powder is the best,and the filling rate is as high as 70.6%.