Inconel758 high temperature alloy
Inconel alloy MA758/ Inconel MA758
1. Chemical composition (wt%):
CCrNiAlTiFeY2O3
0.0530.0 margin 0.30.51.00.6
2. Physical properties:
Density (g/cm3) Melting point (°C)
8.141375
3. Small mechanical properties of the alloy at room temperature:
State yield strength (MPa) tensile strength
(MPa) Elongation%
Rod 56094927
Plate 680103014
4. Characteristics:
1. Good antioxidant properties;
2. Good resistance to glass liquid
5. Application areas:
Applications related to heat treatment and application areas with strict requirements for high temperature metals and alloys, iron melting furnace components such as furnace rollers, clamps, tools, etc.
Inconel758 high temperature alloy
Solid solution strengthened alloys and alloy ingots containing low amounts of aluminum and titanium (the total amount of aluminum and titanium are approximately less than 4.5%) can be forged and billeted; alloys containing high aluminum and titanium are generally billeted by extrusion or rolling. It is then hot rolled into finished products, and some products require further cold rolling or cold drawing. Alloy ingots or cakes with larger diameters need to be forged with a hydraulic press or a rapid forging hydraulic press.
2. Crystallization metallurgical process
In order to reduce or eliminate grain boundaries perpendicular to the stress axis and reduce or eliminate porosity in cast alloys, directional crystallization processes have been developed in recent years. This process causes the grains to grow along one crystallographic direction during the solidification process of the alloy to obtain parallel columnar crystals without lateral grain boundaries. The primary process condition for achieving directional crystallization is to establish and maintain a sufficiently large axial temperature gradient and good axial heat dissipation conditions between the liquidus and solidus lines. In addition, in order to eliminate all grain boundaries, the manufacturing process of single crystal blades needs to be studied.
3. Powder metallurgy process
Powder metallurgy process is mainly used to produce precipitation-strengthened and oxide dispersion-strengthened high-temperature alloys. This process can make cast superalloys that are generally non-deformable obtain plasticity or even superplasticity.
4. Strength improvement process
⑴Solid solution strengthening
Adding elements with different atomic sizes from the base metal (chromium, tungsten, molybdenum, etc.) causes distortion of the base metal lattice, adding elements that can reduce the stacking fault energy of the alloy matrix (such as cobalt), and adding elements that can slow down the diffusion rate of the base elements. Elements (tungsten, molybdenum, etc.) to strengthen the matrix.
⑵ Precipitation strengthening
Through aging treatment, the second phase (γ', γ", carbide, etc.) is precipitated from the supersaturated solid solution to strengthen the alloy. The γ' phase is the same as the matrix, both have a face-centered cubic structure, and the lattice constant is similar to the matrix. And coherent with the crystal, so the γ phase can be uniformly precipitated in the form of fine particles in the matrix, hindering dislocation movement and producing significant strengthening effects. The γ' phase is an A3B type intermetallic compound, A represents nickel and cobalt, and B represents Aluminum, titanium, niobium, tantalum, vanadium, tungsten, while chromium, molybdenum, and iron can be both A and B. The typical γ' phase in nickel-based alloys is Ni3 (Al, Ti).
The strengthening effect of γ' phase can be enhanced through the following ways:
① Increase the number of γ' phases;
② Make the γ' phase and the matrix have an appropriate degree of mismatch to obtain the strengthening effect of coherent distortion;
③Add elements such as niobium and tantalum to increase the antiphase domain boundary energy of the γ' phase to improve its ability to resist dislocation cutting;
④Add elements such as cobalt, tungsten, and molybdenum to increase the strength of the γ' phase. The γ" phase has a body-centered tetragonal structure and its composition is Ni3Nb. Due to the large mismatch between the γ" phase and the matrix, it can cause a large degree of coherent distortion, allowing the alloy to obtain a high yield strength. But above 700℃, the strengthening effect is significantly reduced. Cobalt-based superalloys generally do not contain γ phase, but are strengthened with carbides.
