4 января 2025 года

As a key component in the aerospace and energy fields, turbine components have extremely high requirements for their performance and reliability. Shot peening is an important technical means to optimize the surface of turbine components by introducing residual compressive stress to enhance the materials’ fatigue life and corrosion resistance.

Ceramic shot peening beads and steel shots are the two most commonly used shot peening media. Although both can achieve a certain strengthening effect, there are significant differences in performance, durability, and cost. This article will discuss these comparison points to help users better choose the appropriate shot peening media.

1. Шероховатость поверхности

Although ceramic shot peening beads have high hardness, they do not damage the surface and can produce low surface roughness while maintaining processing efficiency. It is usually suitable for turbine parts with high surface finish requirements, such as aircraft engine turbine blades.

Although it has a strong impact force, it is easy to produce high roughness and is not suitable for turbine parts that require delicate surface treatment.

2. Отделка поверхности

The surface of the zirconia ceramic shot is smooth, and it is not easy to form scratches or dents after impact, which can achieve a uniform surface treatment effect.

Steel shot is usually made of high carbon steel or alloy steel. Although steel has high hardness, its particle structure is relatively fragile. It is easy to deform or disintegrate under high intensity or frequent use, which may lead to an uneven impact effect, thus affecting the overall finish.

3. Stress distribution

Ceramic beads have uniform size and can introduce a uniform and moderate depth of residual compressive stress in the surface layer, which helps to improve fatigue life. The depth of compressive stress distribution usually reaches 0.1-0.15 mm, which is the preferred choice for stress-sensitive parts.

Steel shot can introduce deeper residual compressive stress distribution (depth can reach more than 0.2 mm) due to its higher impact force, but the uniformity of stress distribution may not be as good as ceramic shot peening beads, which have a certain impact on the life of the parts.

4. Coverage

Ceramic beads have high consistency in size and shape, and the shot peening process can easily achieve higher coverage, and the coverage efficiency is usually 10%-15% higher than that of steel shot.

Steel shots are prone to insufficient local coverage due to differences in shape and hardness, and it may take extra time or multiple shot peening to meet the requirements.

5. Uniformity

Ceramic shot peening media is mainly composed of zirconium oxide (accounting for 60%-70%), combined with other oxides. The unique crystal structure has excellent compressive resistance and toughness, is not easy to break, and is especially suitable for high-intensity and repeated-impact working environments. It can maintain a consistent impact effect during the shot peening process and improve the uniformity of the treatment.

However, the breakage rate of steel shots is higher, and particles of different sizes may be produced after shot peening, which affects the consistency of the shot peening process.

1. Corrosion resistance

Ceramic shot peening beads have excellent corrosion resistance and are not easily affected by moisture and chemicals. They are suitable for parts exposed to corrosive environments for a long time. For example, in marine or high-humidity conditions, zirconia ceramic shot can effectively protect the surface integrity of turbine parts.

Steel shots are easily affected by moisture and chemicals. Long-term use may cause rust, which hurts the surface quality of turbine parts. Additional anti-rust treatment is required, which increases the cost and complexity of use.

2. Applicable temperature range

Ceramic materials have high heat resistance and usually maintain a stable structure in high-temperature environments. There will be no material softening or shape change. They are suitable for high-temperature parts such as aircraft engine turbine blades.

Steel shots may fail due to oxidation or performance degradation in ultra-high temperature environments and are not suitable for extremely high-temperature shot peening operations.

1. Долговечность

Ceramic shot peening beads have high wear resistance and a much longer service life than steel shot. Studies have shown that under the same conditions, ceramic shot peening beads can be used 2-3 times more often than steel shot.

Due to structural reasons, steel shot is more likely to crack during high-frequency use, leading to failure, and its life is significantly lower than that of ceramic shot peening beads.

2. Recycling rate

Ceramic beads have a high recycling rate and can be used again after simple cleaning. The loss rate is low, which helps to reduce the media consumption of the overall shot peening operation.

The recycling rate of steel shot is lower than that of zirconia ceramic shot. Due to cracking and deformation, it has a higher loss and needs to be replaced and handled more frequently, which increases the complexity and cost of maintenance.

3. Economy

The unit cost of zirconia ceramic shot is higher, but their durability and high recycling rate make them more economical for long-term use. Steel shot has a low initial purchase cost and is suitable for projects with limited budgets or short-term projects. More attention should be paid to high-intensity shot peening operations.

1. High-precision requirements

Ceramic shot peening beads perform well when processing high-precision parts such as turbine blades and aircraft engine parts. With moderate hardness and uniform particle size, they can provide high-quality surface strengthening effects without damaging the surface.

Especially for workpieces with complex details and high surface quality requirements, such as the grooves and edges of turbine blades, these parts usually require fine control of the impact force and uniformity of the shot peening medium.

2. High-strength requirements

Steel shot has significant advantages in parts that require high-intensity shot peening, such as large turbine bearings and pressure-bearing parts, due to its large impact force.

Suitable for surface strengthening of thick and heavy metal parts, deep residual compressive stress can be quickly achieved, thereby increasing the fatigue life of the parts.

3. Environmental protection requirements

Ceramic beads do not contain iron-based components, produce less dust and pollutants, and meet environmental protection standards. The waste generated during use is also relatively small, which helps to reduce the environmental protection management costs of the factory.

Steel shots may produce iron oxide particles after wear, which requires high environmental management. Frequent replacement will also increase the amount of waste disposal, which is not suitable for production environments that emphasize green manufacturing.

Ceramic shot peening beads and steel shots each have unique advantages and are suitable for different turbine component shot peening needs.

Ceramic beads perform well in the surface treatment of turbine blades and complex components with high precision requirements and can provide uniform and detailed surface strengthening effects, which are suitable for applications requiring high surface quality and long life. Steel shots, on the other hand, show unparalleled advantages with stronger impact force when processing components that require deep compressive stress, such as large turbine bearings and pressure-bearing components.

The two media have their emphasis, and the selection should be based on the specific performance requirements, environmental requirements, and economic budget of the turbine components.

With the continuous advancement of shot peening technology and materials, more innovative shot peening media may appear in the future, providing more precise and environmentally friendly solutions for the efficient treatment of turbine components.