What is nickel-based alloy：
Nickel-based alloys refer to a class of alloys that have high strength and a certain degree of oxidation and corrosion resistance at a high temperature of 650 to 1000 ℃. According to the main performance, it is subdivided into nickel-based heat-resistant alloys, nickel-based corrosion resistant alloys, nickel-based wear-resistant alloys, nickel-based precision alloys and nickel-based shape memory alloys. According to the different substrates, superalloys are divided into iron-based superalloys, nickel-based superalloys and cobalt-based superalloys. Among them, nickel-based superalloys are referred to as nickel-based alloys.
Nickel-based alloys are alloys with nickel as the main component.
It has high heat resistance and is often used for parts exposed to high temperature environments for a long time, such as aero engine parts. During the cutting process, the hardness of the nickel-based alloy hardly softens due to the influence of cutting heat. Therefore, compared with ordinary steel, its processing is very difficult.
When machining nickel-based alloys with cemented carbide tools, there is often a feeling of "fast blade wear and difficult machining".
So next, we will understand the characteristics of nickel-based alloys, and introduce the main points of its efficient cutting.
Material properties of nickel-based alloys：
What is the difference between nickel-based alloy and ordinary steel:
We compared the material properties of a typical nickel-based alloy-Inconel 718 and high carbon steel.
As shown in the figure below, the strength and hardness of nickel-based alloys are significantly higher than that of carbon steel, while its thermal conductivity is only less than 1/3 of that of carbon steel.
|
|
Inconel718 |
S45C |
|
Vickers hardness （HV） |
392~458 |
213~286 |
|
|
1270 |
690 |
|
Specific strength
|
153 |
8 |
|
Thermal conductivity W/m·℃
|
14.6 |
47.0 |
|
Thermal expansion rate
|
13.7 |
10.8 |
The effect of "tensile strength" on cutting tools：
The higher the tensile strength value, the higher the strength of the workpiece. In layman's terms, it has the characteristics of "the workpiece is sticky and the chips are easy to stretch".
Therefore, if the chips cannot be controlled well during the machining process, the phenomenon of chip entanglement is prone to occur.
The processed material with higher "viscosity" has greater cutting resistance and higher cutting heat, which may cause rapid wear or damage of the tool.
The effect of "thermal conductivity" on cutting tools:
Thermal conductivity is a numerical value that expresses the ease of heat transfer to the workpiece material.
When cutting, machining heat is generated between the tool and the workpiece due to friction.
When processing materials with low thermal conductivity, it is difficult to remove the cutting heat through the chips, and most of the cutting heat is concentrated on the cutting tool.
The material properties of the cutting tool itself will change significantly with the environmental temperature.
As can be seen from the figure below, as the temperature increases, the hardness and strength of the cemented carbide tools have significantly decreased, which will accelerate the wear or defect of the tools. This is the reason why "the blade wears quickly and the machining is difficult" when machining nickel-based alloys with cemented carbide tools.
Summary of processing characteristics of nickel-based alloys:
Due to the higher "viscosity" of the processed material, the cutting resistance is greater and the cutting heat is higher, which may cause rapid wear or damage of the tool.
The heat generated during machining is concentrated on the cutting tool, thereby reducing the hardness and strength of the tool, making the tool more prone to wear or damage.
Although nickel-based alloys are difficult to cut, some tools can be machined faster and more efficiently than carbide tools.
---EDITOR: Miya Ma
---POST: Doris Hu
