TZM alloy production process vacuum arc melting method
The vacuum arc melting method uses an arc to melt pure molybdenum, and then adds a certain amount of alloying elements such as Ti and Zr. After thorough mixing, the TZM alloy is obtained through conventional casting methods. The production process of vacuum arc melting includes electrode preparation, water cooling effect, stable mixed arc and melting power, etc. These production processes have a certain impact on the quality of TZM alloy. In order to produce TZM alloys with good properties, strict requirements should be placed on the production process.
Electrode requirements: The electrode composition should be uniform, the surface should be dry, bright, non-oxidized, non-bent, and the straightness should meet the requirements.
Water cooling: In the vacuum consumables melting furnace, the crystallizer has two main functions: one is to take away the heat released during the melting process to ensure that the crystal is not burned; the other is to cool the crystallizer. The second is to affect the internal structure of TZM alloy blank. The crystallizer can transfer intense heat from the bottom and surroundings to the billet, causing the billet to produce a directional columnar structure. When TZM alloy is smelted, the cooling water pressure is controlled at 2.0~3.0kg/cm2, and the optimal water layer is about 10mm.
Stable mixed arc: TZM alloy adds a coil parallel to the crystallizer during the melting process. When electricity is applied, it turns into a magnetic field. The main function of this magnetic field is to restrain the arc and solidify the molten pool under stirring, so this arc restraint is called "stabilizing arc". In addition, having a suitable magnetic field strength can reduce the breakdown of the crystallizer.
Melting power: Melting powder refers to melting power current and voltage, which are important process parameters. Improper parameters will cause TZM alloy melting failure. Selection of the appropriate melting power is largely based on the ratio of the motor to the size of the crystallizer. "L" refers to the distance between the electrode and the crystallizer wall. The lower the L value, the larger the arc covers the molten pool. Therefore, in the case of the same powder, the better and more active the molten pool heating state is. Otherwise, the operation will be difficult.
TZM alloy (molybdenum zirconium-titanium alloy) and physical properties of pure molybdenum compared as follows:
Material | density /g·cm-3 | Melting point /℃ | Boiling point /℃ |
TZM alloy (Ti0.5/Zr0.1) | 10.22 | 2617 | 4612 |
Mo | 10.29 | 2610 | 5560 |
Mechanical Properties of TZM alloy (molybdenum zirconium-titanium alloy) (ri0.5 / Zr0.1) as follows:
Mechanical Properties | Elongation (%) | elasticity modulus GPa | Tensile strength Mpa | yield strength Mpa | fracture toughness MP·m1/2) |
Value | <20 | 320 | 685 | 560-1150 | 5.8-29.6 |
TZM alloy (molybdenum zirconium-titanium alloy) high-temperature tensile strength and elongation:
Temperature | tensile strength(Mpa) | Elongation |
RT | 1140-1210 | 7.5-13.0 |
1000 | 700-720 | 5.2 |
1200 | 320-360 | 9.0 |
1300 | 190-210 | 11.5-13.5 |
1400 | 140-170 | 11-16 |
TZM alloy (molybdenum zirconium-titanium alloy) thermal performance and electrical properties:
Performance | coefficient of thermal expansion /K-1(20~100℃) | thermal conductivity W/m·K | Using maximum temperature in air ℃ | ResistivityΩ·m |
Value | 5.3X10-6 | 126 | 400 | (5.3~5.5)X10-8 |