Titanium ingot casting process
Titanium ingot casting process is generally composed of three stages, one ingredient, the second is the bundled electrode, the third is cast.
One. Ingredients
Titanium alloy ingredients according to the following principles to determine the proportion of ingredients:
(1) the range of alloy elements and impurities allowed fluctuation range and the optimum performance alloy required the best composition range;
(2) melting methods and melting times;
(3) the burning rate and evaporation rate of alloying elements in the vacuum consumption melting process;
(4) the addition of alloying elements and physical properties.
Under normal circumstances, the burning rate, volatile elements easily, ingredients close to the upper limit or over the upper limit, the elements are not impulsive loss according to the requirements of the limited range of ingredients. .
Second, the suppression of the electrode block
Consumable melting electrode requirements are:
(1) adequate strength;
(2) sufficient conductivity;
(3) flatness;
(4) the distribution of alloying elements in the electrode is reasonable;
(5) not damp, no pollution.
Monolithic electrode preparation methods are pressing (also separated pressure and horizontal pressure) and extrusion (also sub-horizontal and vertical) two types, the more commonly used is pressing.
The density of the electrode block is linked to the material being pressed. In general, the electrode block density greater than 3.2g / cm3 to meet the meeting requirements. Generally use the pressure reaches 300 ~ 500MPa presses.
Electrode welding
Electrode welding is the pressure of a fine piece of electrode assembly welding consumable arc melting the required cross-section and length of the electrode. Industry, often using argon plasma arc welding, vacuums plasma welding and electron beam welding. In order to prevent mixing with a high proportion of inclusion, generally do not use TIG welding. The purity of argon for welding is 99.99%.
Third, from the beginning of power smelting to charge all melted (in addition to the molten pool above the solid arch bridge) is completed at the melting furnace charge stage. Melting at the beginning, the newly added charge of larger resistance, the electrode and the charge in direct contact with the charge resistance heating furnace charge, while the input current is small but relatively stable, resistance heat dominant during this period. But this period of time is not long, when the charge below the electrode is melted to form three "crucible melt pool", the electrode and the "crucible pool" between the arc heating heating charge to gradually expand the melt pool until the formation of a communication three electrodes The "big pool." During the transition from "crucible bath" to "large bath", the resistance of the charge gradually decreases due to the reduction of the unmelted charge, and the electric resistance heat between the electrode and the "crucible bath" The proportion of the gradual increase. After about half an hour from the beginning of smelting arc heat will dominate. The above "transition period" is the unstable period of smelting high titanium slag, firstly, the resistance of the circuit passing through by the current (electrode → crucible bath → unmelted charge → crucible bath → electrode) changes with time; and the second is " The solid material above the crucible pool often falls into the pool to cause intense reaction which causes the slag to boil, and this "slump-slag boiling" phenomenon is irregular.
Titanium ingot casting process is generally composed of three stages, one ingredient, the second is the bundled electrode, the third is cast.
One. Ingredients
Titanium alloy ingredients according to the following principles to determine the proportion of ingredients:
(1) the range of alloy elements and impurities allowed fluctuation range and the optimum performance alloy required the best composition range;
(2) melting methods and melting times;
(3) the burning rate and evaporation rate of alloying elements in the vacuum consumption melting process;
(4) the addition of alloying elements and physical properties.
Under normal circumstances, the burning rate, volatile elements easily, ingredients close to the upper limit or over the upper limit, the elements are not impulsive loss according to the requirements of the limited range of ingredients. .
Second, the suppression of the electrode block
Consumable melting electrode requirements are:
(1) adequate strength;
(2) sufficient conductivity;
(3) flatness;
(4) the distribution of alloying elements in the electrode is reasonable;
(5) not damp, no pollution.
Monolithic electrode preparation methods are pressing (also separated pressure and horizontal pressure) and extrusion (also sub-horizontal and vertical) two types, the more commonly used is pressing.
The density of the electrode block is linked to the material being pressed. In general, the electrode block density greater than 3.2g / cm3 to meet the meeting requirements. Generally use the pressure reaches 300 ~ 500MPa presses.
Electrode welding
Electrode welding is the pressure of a fine piece of electrode assembly welding consumable arc melting the required cross-section and length of the electrode. Industry, often using argon plasma arc welding, vacuums plasma welding and electron beam welding. In order to prevent mixing with a high proportion of inclusion, generally do not use TIG welding. The purity of argon for welding is 99.99%.
Third, from the beginning of power smelting to charge all melted (in addition to the molten pool above the solid arch bridge) is completed at the melting furnace charge stage. Melting at the beginning, the newly added charge of larger resistance, the electrode and the charge in direct contact with the charge resistance heating furnace charge, while the input current is small but relatively stable, resistance heat dominant during this period. But this period of time is not long, when the charge below the electrode is melted to form three "crucible melt pool", the electrode and the "crucible pool" between the arc heating heating charge to gradually expand the melt pool until the formation of a communication three electrodes The "big pool." During the transition from "crucible bath" to "large bath", the resistance of the charge gradually decreases due to the reduction of the unmelted charge, and the electric resistance heat between the electrode and the "crucible bath" The proportion of the gradual increase. After about half an hour from the beginning of smelting arc heat will dominate. The above "transition period" is the unstable period of smelting high titanium slag, firstly, the resistance of the circuit passing through by the current (electrode → crucible bath → unmelted charge → crucible bath → electrode) changes with time; and the second is " The solid material above the crucible pool often falls into the pool to cause intense reaction which causes the slag to boil, and this "slump-slag boiling" phenomenon is irregular.
