Materials and heat treatment methods for shaft parts
Material of shaft parts
Different working conditions should be considered in selecting shaft parts. In addition, it is necessary to consider the use requirements of other materials, considering their variation in terms of composition. Finally, it is integral to equally consider using different heat treatment specifications (such as tempering, normalizing, quenching, etc.) to obtain a particular strength, toughness, and wear resistance.
In applying shaft parts, 35, 45, 50, and other high-quality carbon structural steels have high comprehensive mechanical properties. The overall hardness after quenching and tempering can reach 220-250HBS. On the other hand, the surface quenching hardness can reach more than 50HRC. In essence, wide usage of 50HRC surface-quenching is notable.
Carbon structural steels such as Q235 and Q275 can be good for shaft parts that are unimportant or with less force. Thus, heat treatment can be dispensed with such carbon structural steels. In this regard, 45 steel is the most common material for shaft parts that are not that important. This is because the material is cheap.
Quenching and tempering can be used in achieving better cutting performance. It is also notable that such material can obtain higher strength, toughness, and other comprehensive mechanical properties following adequate exposure to quenching. In essence, the surface hardness can reach 45 ~ 52HRC after quenching.
Other Material Options
In cases where medium precision and high-speed requirements are deemed necessary, alloy structural steels such as 40Cr can be used for shaft parts. This is because such steels have better comprehensive mechanical properties after tempering or quenching. Therefore, an alloy is a perfect match in such instances.
Notably, it is easy to reach 50 ~ 58HRC for Bearing steel GCr15 and spring steel 65Mn after tempering and surface high-frequency quenching. It is important to note that manufacturing a higher precision shaft can be achieved when there is adequate surface hardness, high fatigue resistance, and better wear resistance.
Ductile iron and high-strength cast iron materials such as QT600-3 can be used to produce complex stress, strength, toughness, wear resistance, and other high requirements of parts. In this case, it is important to consider vibration damping performance and good impact toughness. Automobiles, tractors, and internal combustion engines are made using such components.
Nitride steel 38CrMoAl can be used for precision machine tools spindles (e.g. grinding wheel shafts, coordinate boring spindles) optional. After tempering and nitriding, this steel can not only obtain a high surface hardness, but also maintain a soft core. Therefore, such impact toughness is good for any mechanical operation.
Carburized steels such as 20CrMnTi, 20Mn2B, and 18CrMnTi can be selected under the working conditions of high speed and large load.
Heat treatment of shaft parts
General shaft parts blank commonly used round bar material and forgings. On the other hand, castings are used for large and complex such as camshafts or crankshafts. After the blank is heated and forged, the internal fiber tissue of the metal can be evenly distributed along the surface to obtain high tensile, bending, and torsional strength.
1) Before processing, the forging blank needs to be arranged for normalizing or annealing treatment. In this regard, the grain inside the steel is refined. Additionally, the forging stress is eliminated and the material hardness is reduced. Most importantly, the cutting processing performance is improved.
2) In the interest of obtaining good comprehensive mechanical properties, tempering is generally arranged after the rough car and before the semi-fine car.
3) The arranging of Surface quenching is done before finishing. Therefore, it is possible to correct the local deformation caused by quenching.
4) low-temperature treatment is deemed necessary for shafts with high precision requirements after local quenching or rough grinding.
Factors Crucial In Heat Treatment
The heat treatment process is also different due to different applications. In this case, difference applies to specific materials, such as:
45 steel, can achieve a local hardness of HRC62-65, after quenching and tempering treatment (hardness 235BHS), and the subsequent local high-frequency quenching. It if further notable that reduction to the required hardness can be done after appropriate tempering treatment,
40Cr and other alloy structural steel can reach 48-55HRC after quenching and tempering. High-frequency quenching has high comprehensive mechanical properties and surface quenching hardness of 52-60HRC. Flame quenching; After tempering, nitriding can also be done, and the hardness can reach 72~78HRA. In this case, the heart hardness can reach 43~55HRC.
Bearing steel GCr15 and spring steel 65Mn and other materials go through quenching and tempering treatment. This helps to improve the strength, hardness, wear, and fatigue resistance of steel. Notably, the performance obtained by different quenching processes and cooling methods will also vary depending on specific factors.
Normalizing and tempering process generally heat-treat the cast iron. Improvement of strength, hardness, and wear resistance of ductile iron is achievable through thorough quenching and tempering process. Low-carbon gold-containing steels such as 20CrMnTi have high surface hardness, impact toughness and heart strength after carburizing and quenching.