High Temperature Alloy Properties

Various degradation rates of materials are accelerated in high-temperature environments. During use, tissue instability, deformation and crack growth under the action of temperature and stress, and oxidative corrosion of the material surface are prone to occur.

1. High temperature resistance and corrosion resistance
The high temperature resistance, corrosion resistance and other properties of high temperature alloys mainly depend on its chemical composition and organizational structure. Taking the GH4169 nickel-based deformed high-temperature alloy as an example, it can be seen that the niobium content in the GH4169 alloy is high. The segregation of niobium in the alloy is directly related to the metallurgical process. The matrix of GH4169 is a Ni-Gr solid solution, and the mass fraction of Ni containing more than 50% can be tolerated. At a high temperature of about 1 000°C, it is similar to the American brand Inconel718. The alloy is composed of γ matrix phase, δ phase, carbide and strengthening phase γ' and γ″ phases. The chemical elements and matrix structure of GH4169 alloy show its strong mechanical properties. The yield strength and tensile strength are several times better than 45 steel, and the plasticity is also better than 45 steel. The stable lattice structure and a large number of strengthening factors contribute to its excellent mechanical properties.

2. High processing difficulty
Due to its complex and harsh working environment, the integrity of the processed surface of high-temperature alloys plays a very important role in its performance. However, high-temperature alloys are typically difficult-to-machine materials. They have high microhardness, severe work hardening, high resistance to shear stress and low thermal conductivity. The cutting force and cutting temperature in the cutting area are high, which often occurs during processing. The machined surface quality is low and the tool is severely damaged. Under normal cutting conditions, the surface layer of high-temperature alloy will produce excessive problems such as hardened layer, residual stress, white layer, black layer, and grain deformation layer.