In the field of high-end machinery manufacturing, the service conditions of parts are becoming increasingly demanding, and the requirements for reliability, durability and service life are constantly increasing.
Against this background, surface strengthening engineering is developing from a common process to a key link in high-end manufacturing.
The reasons are mainly reflected in the following aspects.
The failure of most mechanical parts begins on the surface or subsurface.
A large number of engineering failure analysis statistics show that fatigue fracture, wear and corrosion are the main failure forms of mechanical parts, and these three types of problems often start on the surface or near-surface area of the part.
The surface is the first interface to withstand external loads, media and environmental effects, and its microscopic state directly affects the service behavior of parts.
Therefore, from the perspective of failure prevention, improving surface quality has become a necessary means to improve overall reliability.
Surface optimization has become an important way to improve the performance of matrix materials.
After long-term development, the pace of progress in improving the overall mechanical properties of metal materials through alloy design and heat treatment is slowing down.
Under the multiple constraints of weight, cost and processability, it is often not economical or feasible to rely solely on replacing the overall material with a higher grade.
Surface strengthening can improve the hardness, residual stress state and organizational structure of the surface layer without changing the geometry and main material of the part, thereby significantly improving the fatigue resistance, wear resistance and corrosion resistance.
This local optimization strategy has high efficiency in engineering.
Take ultrasonic rolling technology as an example. This process combines ultrasonic vibration with traditional rolling processing, and uses the tool head to apply the combined effect of high-frequency impact and static pressure rolling on the surface of the part, causing plastic flow of the surface material to form a nanoscale or sub-micron fine-grained structure. At the same time, a residual compressive stress field of a certain depth and amplitude is introduced.
The surface roughness of the treated parts is significantly reduced, the microhardness is increased, and the fatigue resistance is improved.
This technology has been applied in engineering applications on shafts, rollers and other parts.
Lightweight design places higher requirements on surface integrity.
Fields such as aerospace, rail transportation and new energy vehicles continue to pursue weight reduction to gain gains in energy efficiency and load.
When the component section is thinned and the wall thickness is reduced, the structure’s sensitivity to surface defects and stress concentration increases significantly.
Minor surface damage, machining marks or local residual tensile stress may become the starting point of fatigue cracks.
Therefore, the realization of lightweight structures often requires high-level surface strengthening processes to create a predictable surface integrity state and ensure the realization of the design life.
In such applications, surface strengthening has become one of the basic conditions for ensuring lightweight safety.
Remanufacturing and long-life design rely more heavily on surface strengthening technology.
The full life cycle cost of high-value equipment (such as gas turbines, large transmission systems, and core components of construction machinery) has attracted increasing attention.
When surface damage occurs to key components, surface engineering methods such as thermal spraying and laser cladding can be used to repair and restore performance, which can maintain the properties of the base material while making the performance of the parts reach or even better than that of new products.
This remanufacturing path results in significant savings in raw material and manufacturing costs, as well as reduced downtime.
In addition, in order to extend product life from the design stage, manufacturers are increasingly using surface strengthening methods such as ultrasonic rolling to proactively implant beneficial residual compressive stress on the surface of parts to delay the initiation and expansion of cracks.
Surface strengthening therefore becomes an integral part of the long-life design.
Improved process controllability promotes the application of surface strengthening engineering.
In the past, the implementation effect of some surface strengthening technologies was highly dependent on the operator’s experience, and the relationship between process parameters and surface integrity was not transparent enough, resulting in large dispersion of results and difficulty in passing strict certification.
In recent years, with the introduction of online monitoring sensors, data collection and analysis and other technologies, key indicators such as shot peening intensity, coverage rate and residual stress distribution can be sensed and controlled online in a closed loop.
Processes such as ultrasonic rolling also benefit from this trend. Its core parameters such as vibration frequency, static pressure, and feed speed can be accurately controlled and recorded, and the repeatability of the enhanced effect continues to improve.
Surface strengthening is transforming from an experience-based craft to a measurable, repeatable, and verifiable branch of manufacturing engineering.
This certainty enables high-safety-level industries such as aerospace engines and nuclear energy equipment to incorporate them into formal process specifications and promote their application.
The pursuit of part performance in high-end machinery manufacturing extends the manufacturing focus from the material body to the surface.
Due to its systematic value in failure prevention, lightweight support, life extension and process controllability, surface strengthening engineering has developed into an indispensable link in the product design, process development and cost management chain. Its continued rise in status is in line with the objective logic of technological evolution.
