What are the advantages of quenched shafts compared to ordinary shafts?

As a key component connecting marine motor products and driven equipment, the installation size and mechanical performance compliance of the shaft are crucial. Most marine motor products use 45 # steel as the shaft, but for some special purpose marine motors, due to relatively harsh load conditions, forged or tempered shafts will be used.

Simply put, quenching and tempering treatment refers to a dual heat treatment method of quenching and high-temperature tempering of materials, aimed at improving the comprehensive mechanical properties of metal materials. Through quenching and tempering treatment, the strength, plasticity, and toughness of steel are all improved to a certain extent, and it has good comprehensive mechanical properties. Compared with ordinary shafts, the main advantage of quenched and tempered shafts is that they have better toughness, can resist the impact of impact loads, and prevent malignant quality accidents caused by shaft fracture.

45 steel is a medium carbon structural steel with good cold and hot workability, good mechanical properties, low price, and wide sources, therefore it is widely used. But its weakness is low hardenability, and it is not suitable for workpieces with large cross-sectional dimensions and high requirements. Therefore, for motor shafts with high mechanical performance requirements, 40Cr steel is more commonly used for quenching and tempering treatment.

During the quenching and tempering process of 40Cr steel, Cr can increase the hardenability of the steel, improve its strength and tempering stability, and possess excellent mechanical properties. Chromium steel is used for larger or important quenched and tempered workpieces.

Quenching and tempering is a crucial professional machining process, and the selection of temperature, time, heating rate, and quenching fluid is crucial. The size and shape of the workpiece also affect the quenching and tempering effect. For example, after high-temperature tempering of 40Cr workpieces, those with complex shapes need to be cooled in oil, while those with simple shapes can be cooled in water, in order to avoid the influence of the second type of tempering brittleness. After tempering and rapid cooling, if necessary, the workpiece should be treated with stress relief techniques.

In the actual quenching and tempering process, unreasonable parameter selection may lead to adverse phenomena such as material cracking. Some marine motor manufacturers have their own quenching and tempering processes, while others tend to use outsourced quenching and tempering methods. Anyway, achieving true quenching and tempering treatment effect is the correct way to ensure the ability of marine motors to withstand harsh loads during operation.