What are the benefits of Dalian shot blasting processing on metal surfaces

In modern industrial manufacturing, the performance of metal components depends not only on the characteristics of their materials themselves, but also on their surface state. A carefully treated metal surface can greatly improve the fatigue life, corrosion resistance, and overall reliability of parts. Among numerous surface treatment technologies, Shot Peening in Dalian has become an indispensable key process for improving the surface properties of metals due to its unique and efficient mechanism. It is not simply cleaning or deburring, but a strengthening method that can fundamentally improve the mechanical properties of metals.

1、 The core mechanism of shot blasting processing: inducing compressive stress and resisting the source of fatigue

To understand the benefits of shot blasting, it is necessary to first understand its core working principle - inducing the formation of a surface compressive stress layer.

When metal parts are subjected to alternating loads (such as repeated bending and twisting), their failure mode is often not sudden fracture, but "fatigue failure". Fatigue cracks typically originate from small defects, scratches, or stress concentration points on the surface of the component. Under the repeated action of tensile stress, these microcracks will gradually propagate, ultimately leading to the fracture of the part.

Shot blasting process continuously impacts the metal surface with high-speed pellets (steel pellets, ceramic pellets, glass pellets, etc.), like countless small hammers performing high-frequency hammering. This type of impact can cause small, plastic extending indentations in the metal surface material and attempt to expand outwards. However, the materials around and below the impact point maintain their original shape, thereby strongly constraining the expansion of the surface material. This state of "surface expansion without success" ultimately forms a stable and dense residual compressive stress layer within a certain depth below the surface of the part.

This compressive stress layer is a "golden bell shield" that resists fatigue. When the component is subjected to subsequent working loads, the tensile stress on its surface must first offset the pre-existing compressive stress layer before actual tensile stress can begin to occur. This is equivalent to significantly increasing the "threshold" for parts to withstand fatigue loads, greatly delaying the initiation and propagation of fatigue cracks, thereby greatly improving the fatigue strength and fatigue life of the parts. This is the core and valuable benefit of shot blasting processing.

2、 Multiple benefits brought by shot blasting processing

In addition to the core advantage of improving fatigue resistance, shot blasting also brings a series of complementary benefits to metal surfaces:

1. Significantly improve resistance to stress corrosion cracking (SCC)

Stress corrosion cracking is a very dangerous form of failure under the combined action of tensile stress and corrosive media. As mentioned earlier, the surface compressive stress introduced by shot blasting can effectively counteract the working tensile stress, eliminating the necessary condition for stress corrosion cracking (tensile stress) from the root, making the parts safer and more reliable in corrosive environments. This is crucial for equipment applied in fields such as chemical, marine, and energy.

2. Form a reinforced surface to enhance wear resistance

The impact of high-speed projectiles causes distortion of the surface metal lattice, refinement of grains, and a sharp increase in dislocation density. This process is essentially a work hardening effect. The surface hardness is thus improved, enhancing the ability of the parts to resist friction, wear, and minor scratches, especially suitable for components that frequently come into contact and move relative to each other.

3. Eliminate trace residual tensile stress and correct shape

During mechanical processing (such as milling, grinding, turning) or heat treatment (such as quenching), the surface of the part may generate unfavorable trace residual tensile stress, which is a "breeding ground" for fatigue cracks. Shot blasting can effectively eliminate these harmful stresses and convert them into beneficial compressive stresses. Meanwhile, for certain thin-walled or plate-shaped components, controlled shot blasting can be used to correct their warping deformation and restore their design shape.

4. Integrate surface cleaning and pretreatment

While strengthening the metal, the shot blasting process also effectively removes all pollutants such as oxide scale, rust, welding slag, and old coatings on the surface, providing a clean and more active surface for subsequent painting, spray painting, electroplating, and other processes. The surface after shot blasting will form a uniform roughness (i.e. anchor pattern), greatly increasing the contact area between the coating and the substrate, enhancing the mechanical biting force, and making a qualitative leap in the adhesion of the coating, effectively avoiding coating peeling and detachment.

5. Improve surface quality and consistency

Shot blasting treatment can mask subtle surface defects, such as minor knife marks, mold marks, etc., to obtain a uniform, matte, and beautiful surface texture, improving the appearance quality and consistency of the product.

3、 Application Fields

Due to the excellent benefits mentioned above, shot blasting is widely used in industries that require high reliability and safety:

Automotive industry: engine valves, springs (suspension springs, valve springs), connecting rods, gears, driveshafts.

Aerospace: engine blades, turbine discs, landing gear, fuselage structural components. This is an area where shot blasting technology is applied rigorously.

Energy industry: Large gears, bearings, blade shafts for wind turbines.

General machinery: various high load shafts, leaf springs, coil springs, etc.

In summary, shot blasting is far from a simple surface cleaning technique. It is a precision process that cleverly changes the stress state of the metal surface through mechanical means. Its great value lies in inducing residual compressive stress layers, fundamentally suppressing the initiation and propagation of fatigue cracks, and exponentially extending the service life of parts. At the same time, it integrates multiple functions such as strengthening, hardening, cleaning, and pretreatment, significantly improving the comprehensive performance, reliability, and durability of metal parts on its own. In today's pursuit of high-end manufacturing and material limited performance, shot blasting is undoubtedly an indispensable key surface engineering technology in modern industry.