When smelting titanium and titanium alloy ingots using a vacuum consumable arc furnace, proper control of certain factors is crucial to prevent defects such as cold shuts, inclusions, and porosities on the ingot surface and enhance its metallurgical quality. The following four aspects should be given special attention during production:
Four Aspects of Titanium and Titanium Alloy Ingots in Production
Ensuring uniform chemical composition: The content of various alloying elements should meet standard requirements and be consistently controlled at an optimal level.
Controlling major impurities: Keep the content of impurities like Fe and O within appropriate ranges while ensuring compliance with standard requirements for other impurities.
Eliminating impurities and defects: Ensure the absence of impurities, segregation, gas porosity, cracks, shrinkage, and looseness within the ingots.
Achieving a smooth surface: Minimize surface defects such as cold shuts and wrinkles, and reduce head shrinkage to achieve a high yield of finished ingots.
To ensure quality control in each production process, it is essential to focus on quality control at every stage of manufacturing.
1
Raw Material Selection
Titanium sponge and intermediate alloys are the primary raw materials for titanium alloy ingot casting. Sieving methods are used to remove excessively large and small titanium sponge particles, ensuring a more uniform particle size distribution.
2
Blending
Determine the chemical composition of the ingot, considering both upper and lower limits of the main elemental proportions. Minimize impurity elements and ensure they don't exceed specified values.
3
Mixing and Compression
Homogenize the raw materials through mixing to achieve a uniform chemical composition within the ingot. Compress the uniformly mixed raw materials into electrode blocks using an oil press machine.
4
Electrode Preparation
Assemble and weld the electrode blocks to create consumable electrodes for the primary melting process. Welding methods such as hydrogen arc welding or plasma welding should be used with adequate protection, preferably under an inert gas atmosphere or within a welding chamber, to prevent the formation of refractory oxides and nitrides.
5
Melting Process
The melting process is a critical stage in producing titanium and titanium alloy ingots. Important process parameters affecting ingot quality include current, voltage, stable arc current magnitude, and duration of stable arc stirring.
