Distribution Characteristics of Inclusions in GH4742 Superalloy Ingot by Vacuum Arc Remelting

doi:10.20057/j.1003-8620.2024-00090

Abstract

Abstract: A ϕ570 mm alloy ingot was utilized as the electrode for vacuum arc remelting， and a ϕ660 mm vacuum arc remelting ingot was prepared through the three stages of arc initiation， stabilized melting， and thermal capping. The melting process lasted a total of 860 minutes.The distribution of inclusions in the industrial ingot of vacuum arc remelting GH4742 alloy and its characteristic positions （crown， shelf and skin） was analyzed by field emission scanning electron microscope and inclusion automatic scanning system. The results of the study showed that there were four main types of inclusions in GH4742 alloy vacuum arc remelting ingots， including Ti（C，N）， LaAlO₃-Ti（C，N）， Ti（C，N）-（Ti，Nb，Mo）C， and LaAlO₃-Ti（C，N）-（Ti，Nb，Mo）C. The size of inclusions was mainly dominated by small-sized inclusions less than 3 μm. From the center to the edge， the size of inclusions gradually decreased and the number density gradually increased. The largest size of inclusions was observed at the middle center of the ingot， with a maximum average size of 4.14 μm. The lowest number of inclusions was observed at the bottom center of the ingot with a number density of 13.23 N/mm². The aggregated oxide inclusions were distributed in the ingot crown， skin and shelf， which were formed when the oxides dislodged from the electrodes move to the edges of the ingot under the action of the flow field of the molten pool and are captured by the solidified regions at the edges.

Key words: GH4742 Alloy, Vacuum Arc Remelting （VAR）, Impurity Element, Inclusion

摘要： 以ϕ570 mm的合金锭作为自耗重熔的电极，通过起弧、稳定熔炼和热封顶三个阶段，制备ϕ660 mm的真空自耗铸锭，熔炼过程共历时860 min。采用场发射电子扫描显微镜和夹杂物自动扫描系统，分析了真空自耗重熔GH4742合金工业铸锭内部及其特征位置（锭冠、搁架、橘皮）处夹杂物的分布规律。结果表明，GH4742合金真空自耗铸锭中夹杂物的类型主要有Ti（C，N）、LaAlO₃-Ti（C，N）、Ti（C，N）-（Ti，Nb，Mo）C及LaAlO₃-Ti（C，N）-（Ti，Nb，Mo）C四种。夹杂物的尺寸主要以<3 μm的小尺寸夹杂物为主，从中心到边缘夹杂物的尺寸逐渐降低，夹杂物的数量密度逐渐增多。铸锭中部中心处夹杂物的尺寸最大，最大平均尺寸为4.14 μm。铸锭底部中心处的夹杂物数量最少，数量密度为13.23个/mm²。铸锭锭冠、橘皮及搁架处分布着聚集的氧化物夹杂，这是电极上脱落的氧化物在熔池流动作用下运动到铸锭边缘，被边缘凝固区域捕捉形成的。

关键词: GH4742合金, 真空自耗重熔, 杂质元素, 夹杂物

CLC Number:

TF807

Yang　Shulei, Wang　Xiwei, Tian　Qiang, Wang　Tiantian, Yang　Shufeng. Distribution Characteristics of Inclusions in GH4742 Superalloy Ingot by Vacuum Arc Remelting[J]. Special Steel, 2024, 45(4): 61-67.

杨曙磊, 王曦伟, 田强, 王田田, 杨树峰. GH4742合金真空自耗铸锭中夹杂物分布特征[J]. 特殊钢, 2024, 45(4): 61-67.

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