Author: fc87

Rivet Welding Processing PlantThe future: automation and intelligent transformation
1 Industry changes and opportunities
As a basic service of manufacturing industry, riveting and welding processing is experiencing profound technological changes. Traditional welding and riveting processes are gradually integrating with automation and digital technology, driving rivet processing plants towards higher efficiency and quality. In this article, we will discuss this transformation trend and share our practical experience in automation and intelligence.

2 Application of automated riveting technology
2.1 Robotic welding systems
We have introduced a number of robotic welding systems that offer significant advantages in riveting and welding processes:

Improving Consistency: Eliminating Human Influence on Weld Quality

Enhancing efficiency: enabling continuous 24-hour operations

Reduced difficulty: Simplified welding process for complex weld seams

Improvement of the working environment: Reduction of welders’ exposure to fumes and bright light-7

2.2 Automated detection systems
The automation of quality control is another important feature of an intelligent riveting and welding plant:

Visual recognition system: automatic identification of weld locations and cosmetic defects

Automated ultrasonic inspection: total rather than random inspection of the internal quality of the weld seam

Real-time data monitoring: collecting and analysing welding parameters for quality alerts

2.3 Intelligent production management system
We have developed a production management system specifically for riveting and welding:

Intelligent order scheduling: automatic scheduling according to equipment load and delivery date.

Accurate calculation of materials: automatic calculation of material requirements, reducing surplus materials

Production process tracking: real-time monitoring of production progress and bottleneck processes-4

3 Practical Path of Intelligent Transformation
Based on our experience.Rivet Welding Processing Plant The intelligent transformation of the can be implemented in steps:

3.1 Primary stage: basic automation
Key Steps:

Introduction of a single robotic welding workstation

Implementation of the underlying digital management system

Training of employees in the operation of automated equipment

3.2 Intermediate level: systems integration
Key Steps:

Establishment of automated welding lines

Implementation of MES (Manufacturing Execution System)

Building an internal data collection and analysis platform

3.3 Advanced stage: intelligent decision-making
Key Steps:

Application of artificial intelligence algorithms to optimise process parameters

Enabling predictive maintenance based on big data

Building “digital twins” to simulate and optimise production – 4

4 Transformational benefits and challenges
4.1 Measurable benefits
Since the implementation of automation, our riveting and welding operations have achieved significant results:

Production efficiency: Increase of 35% or more

Material utilisation: from 85% to 93%

Product quality: the passing rate of one-time delivery inspection reaches 98.5%.

Energy efficiency: energy consumption per unit of product reduced by 22%

4.2 Challenges and solutions
The transformation process has also presented us with a number of challenges:

Shortage of technical personnel: building technical teams through internal training and external importation

Investing under pressure: adopting a phased investment strategy to ensure returns at every step of the way

Convergence of traditional processes and automation: retention of some traditional processes and gradual transition

5 Future prospects
With the further development of Industry 4.0 technology, more new trends will emerge in riveting and welding plants:

Flexible production: adapting to the market demand for small quantities and multiple varieties

Remote monitoring and service: remote diagnosis and maintenance of equipment through IoT technology

Green manufacturing: use of more environmentally friendly welding materials and processes-7

6 Conclusion
Automation and intelligence are not multiple choice questions, butRivet Welding Processing Plant The road to survival and development. As a member of the industry, we will continue to promote technological innovation to provide customers with better quality and more efficient riveting and welding processing services. Welcome peers and customers to visit and exchange, and jointly promote the progress of the industry.

Riveting andmachining: How to choose a reliable partner?
1 Specialised Rivet Welding Machining Services Detail
Riveting is a key process in modern manufacturing, where metal parts are securely joined together by riveting, welding and other means. Our riveting and welding fabrication services cover a wide range of processes, including:

Arc welding: for large structural parts and thick plates

Gas Shielded Welding: Provides Cleaner, More Accurate Welds

Resistance welding: suitable for mass production

Laser welding: Towards high-precision, micro-deformation welding

With our advanced equipment and experienced technical team, we can provide the most suitable welding solution according to your project needs-7.

2 Precision machining capability
As a specialised machine shop, we offer a full range of services from prototyping to mass production. Our machining capabilities include:

CNC machining: high precision, high repeatability part production

Turning: Machining of shafts, discs and other rotary parts

Milling: planar and curved surfaces of complex shapes

Drilling: Hole machining of various sizes

We understand the importance of precision machining to product quality, so we strictly implement the ISO 9001 quality management system to ensure that every part meets specifications-6.

3 Quality Assurance and Industry Applications
Quality is the lifeline of manufacturing. We ensure product quality through multiple testing processes:

Incoming Material Inspection: Strict testing of all incoming materials

Process control: real-time monitoring of key parameters during the production process

Final Inspection: Use CMM, hardness tester and other professional equipments to carry out comprehensive inspection on the finished products.

Our riveting and machining services have been used in a wide range of industries:

Aerospace: welding and machining of aircraft structural and engine components

Automotive manufacturing: body welding, engine parts machining

Heavy equipment: Manufacture of structural parts for excavators, cranes and other large equipment

Energy sector: Manufacture of metal structures for wind power equipment and oil rigs-3

4 Frequently Asked Questions
Q: What is the maximum size of workpiece your riveting process can handle?
A: Our factory has large welding platforms and lifting equipment that can handle large workpieces up to 12 metres in length and 8 tonnes in weight.

Q: Can you provide small batch machining service?
A: Sure. We accept a wide range of orders from small trial runs to large-scale production, and are flexible enough to adjust to your needs.

Q: How to ensureWelding quality?
A: All of our welders hold professional certifications and use non-destructive testing techniques (e.g., X-ray, ultrasonic testing) to assess the quality of critical welds-7.

If you are looking for a reliable riveting processing plant and machining service provider, please feel free to contact us. We will provide you with professional advice and quality services.

Rivet welding technologyInnovation: from traditional processes to modern hybrid solutions
1 Overview and classification of riveting technology
Riveting has been developed for centuries as a classic mechanical joining technique. Traditional riveting creates a mechanical locking at the connection site through plastic deformation to achieve the transfer of force. With technological progress, especially the emergence of new technologies such as stirring friction riveting welding, riveting welding has developed from a purely mechanical connection to a hybrid connection technology combining mechanical locking and metallurgical bonding.

Modern riveting technology can be based on the form of riveting and rivet structure, mainly divided into self-riveting stirred friction riveting and self-pierce spinning riveting two categories. In self-riveting stirred friction riveting, no pre-made rivets are used for the connection of plates of dissimilar materials. In the lower plate prefabricated holes of the appropriate shape, with the stirring head movement, the upper material in the friction under the action of heat softening and extrusion downward flow, into the lower plate prefabricated holes to form a similar rivet structure. And the process of self-pierce spin riveting mainly includes four stages: rivet point seeking, stirring self-tapping holes, stirring deformation locking and emergency stop solid welding.

2 Friction Stir Rivet Welding Technology Details
2.1 Stirring Frictionrivet weldingPrinciples and Processes
Stir friction rivet welding technology is an emerging technology to stabilise the connection of dissimilar materials, which adopts the rotational friction of rivets to generate heat, while retaining the deformation locking and solid-phase welding characteristics of rivet welding technology. Regarding friction stir riveting welding, there have been related researches in various universities at home and abroad, but the focus is on the organisation and mechanical property characterisation of friction stir riveting welded joints as well as the analysis of failure forms.

Haris et al. studied the micro-stirred friction rivet welding technique to connect multilayer Al/Cu ultra-thin plates, and the test results showed good interlayer bonding and the existence of nanoscale diffusion layer.William studied the double-sided stirred friction self riveting welding technique, and the test in the pre-fabricated holes to form a continuous rivet-like connecting joints, joints not only to form a metallurgical combination of the material level, but also in the riveting weld joints in the lower part of the formation of an effective mechanical locking. The joint not only formed a metallurgical bond at the material level, but also formed an effective mechanical lock at the lower part of the rivet weld head.

2.2 Joint form and bonding mechanism of stir friction rivet welding
The joint forms of stirred friction riveting can be subdivided into four types depending on the form of riveting as well as the structure of the rivet: stirred friction blind riveting technology (FSBR), stirred spin riveting (FSPR), rotary friction drilled riveting (RFDR) and rotary friction pressure riveting (RFPR).

Typical stir friction self riveting weld fittings differ in construction from self-pierce spin riveting stir friction riveting weld fittings. When joining aluminium alloys to steel by friction stir rivet welding technology, the aluminium plate is usually placed on top and the steel plate on the bottom. Generally, holes of a certain shape are prefabricated in the steel plate in order to form a strong rivet-like joint after riveting. According to the research results of Huang et al, in the process of welding aluminium alloy and steel by stirring and friction self riveting welding, the sequence of material filling follows the following law: firstly, the aluminium alloy deformed at the tip of the rivet, secondly, the aluminium alloy stirred in the stem of the rivet, and lastly, the aluminium alloy pressed in due to the feeding of the rivet.

3 Relationship between microstructure and properties in the riveted welded joint region
3.1 Microstructural characteristics of the joint area
The study of the microstructure of the friction stir rivet welded joint region can promote a deeper understanding of the tissue-property relationship, thus further controlling the overall performance of friction stir rivet welded joints.

According to the organisational evolution law, the stirring friction self-riveting welding head region can be divided into the stirring region (SZ) or welding block (WNZ), the thermo-mechanical influence zone (TMAZ), the plastic deformation metal flow zone (PDZ) or the self-riveting region (SRZ). Compared with the matrix organisation, the SZ region is significantly finer, with the finest grains and a microstructure of fine equiaxial crystals, while the PDZ region is significantly coarser but finer than the matrix, with coarser equiaxial crystals, and the TMAZ region is finer and the grains are significantly deformed due to the effects of mechanical stirring.

3.2 Intermetallic compounds at the interface and their effects
At the interface of aluminium alloy and steel friction stir riveting welding, FexAly (x<y) type intermetallic compounds are easily formed, which is harmful to the performance of the joint.Huang et al. showed that the interface of aluminium alloy and steel friction stirring riveting welding is smooth and tightly bonded, and there are no obvious cracks, holes and other defects were found.The results of the TEM inspection showed that the intermetallic compounds generated are Fe4Al13.Sun et al. detected flaky Fe2Al5 and diffusely distributed lumpy FeAl6 at the interface of 6061 aluminium alloy and low carbon steel. et al. detected flaky Fe2Al5 and diffusely distributed massive FeAl6 intermetallic compounds at the interface between 6061 aluminium alloy and mild steel stir friction rivet welding.

Numerous studies have shown that the formation of Al-rich intermetallic compounds such as Fe2Al5 and FeAl3 negatively affects interfacial bonding as well as joint strength compared to the formation of Fe-rich intermetallic compounds such as FeAl and Fe3Al. This finding provides an important direction for optimising the rivet welding process.

4 Rivet Welding ProcessOptimisation and Performance Improvement Strategies
4.1 Optimisation of process parameters
The riveting process parameters have a decisive influence on the quality of the joint. In self-pierce spin riveting, the root cut d (the radial distance from the interface of the rivet and plate bond to the tip of the rivet), the rivet depth h (the depth of the rivet into the lower plate), and the inter-plate distance between rivets close to the rivet stem are all critical parameters. In general, larger root cuts and rivet depths indicate stronger mechanical locking co-operation, whereas larger values of δ signify reduced rivet depth and weakened mechanical locking co-operation.

Wang Xijing et al. investigated the effect of two joint forms of implanted stirred friction rivet welding on the performance, and the experimental results showed that the joint form with a nail cap on the backside had the aluminium column sheared into two parts along the interface during the stretching process, whereas the joint form without a nail cap on the backside had the aluminium column pulled out directly from the hole during the stretching process. Therefore, in order to achieve mechanical locking of the rivets, i.e. to form a nail cap structure, a suitable matching mould needs to be placed underneath the prefabricated holes, which places more stringent requirements on the placement and space of the rivets.

4.2 Material optimisation and surface treatment
The performance of rivet welded joints can be significantly improved through material optimisation and surface treatment. The addition of Zn or the use of galvanised steel in the friction stir rivet welding of aluminium and steel will promote the formation of Al-Zn intermetallic compounds and reduce the formation of harmful Fe-Al intermetallic compounds.

The microstructure evolution of self-pierce spin riveted AA611 aluminium alloy and galvanised steel rivets has been observed and characterised by Min et al. The joint area can be divided into three typical regions according to the microstructure evolution, all of which are distributed in a circular arc centred on the rivet: region X (>773 μm from the edge of the rivet), region A (within the range of 363~773 μm from the edge of the rivet) and region B (within the range of 88~363 μm from the edge of the rivet). Different regions have different grain boundary characteristics and grain refinement, reflecting different thermo-mechanical histories.

5 Prospects for the application of riveting welding technology and development trend
5.1 Prospects for use in joining dissimilar materials
With the increasing demand for lightweight as well as energy saving in the industrial field, the application of aluminium and magnesium alloys is in increasing demand, while aluminium and magnesium alloys alone have low strength and stiffness, and need to be used in combination with high-strength materials such as steel. Therefore, the connection of dissimilar materials, especially the connection of lightweight alloys such as aluminium alloys and magnesium alloys with steel is particularly important, focusing on the need to solve the problem of combining dissimilar materials with high strength and high precision.

Traditional methods of joining dissimilar materials include riveting, welding and gluing, but there are many drawbacks in these methods, such as poor universality, poor strength and stability of the connection, and difficulty in controlling accuracy. Emerging technologies such as stir friction riveting and welding provide effective solutions to these challenges, especially in high-end manufacturing areas such as automotive, aerospace, etc., demonstrating broad application prospects.

5.2 Trends in technology development
The future development of riveting technology will pay more attention to process precision, efficiency improvement and adaptability expansion. On the one hand, the consistency of joint quality will be improved through the precise control of process parameters and the strengthening of process monitoring; on the other hand, the production efficiency will be improved and the production cost will be reduced through the innovation of equipments and the optimisation of processes.

Digitalisation and intelligence are also important directions in the development of riveting technology. Through the integration of sensors, data analysis and control systems, real-time monitoring and adaptive control of the riveting process can be realised to ensure the stability and reliability of joint quality. At the same time, process optimisation based on digital twin technology will also become an important means to improve the quality of riveting welding

advanced (technology)Welding technologyDissolution control and quality management in
1 Overview of welding technology and the role of dissolution in welding
Welding technology, as one of the core processes of modern manufacturing, achieves permanent connections by bringing materials to an atomic or intermolecular union through various heat sources. In this process, the dissolution phenomenon is ubiquitous, from the formation of the molten pool of fusion welding to the dissolution of the base material of brazing, all directly affect the quality of the final joint. With the development of the manufacturing industry to the direction of high strength, lightweight, high efficiency, welding technology continues to innovate, the precise control of the dissolution process puts forward higher requirements.

In high-tech fields such as aerospace and automotive manufacturing, the quality of welded joints is directly related to the safety and reliability of the entire structure. In automotive manufacturing, for example, body welding involves a wide range of materials and thicknesses, requiring control of different dissolution behaviours to ensure consistency. Similarly, in aerospace, the joining of lightweight alloys to speciality steels must precisely control interfacial reactions to avoid the formation of harmful phases. Understanding and controlling dissolution phenomena during welding is therefore an indispensable technical element of modern manufacturing.

2 Dissolution characteristics and control methods in major welding processes
2.1 Dissolution and erosion control in brazing
The core process of brazing, as a process that relies on capillary action to fill the joint, is the mutual dissolution between the base material and the brazing material. In brazing of aluminium heat exchangers, dissolution and erosion are particularly evident. It has been shown that the maximum temperature and holding time during brazing, as well as the type and amount of brazing material, affect the degree of dissolution and erosion.

By comparing three different brazing profiles (normal, heated and strongly heated), it was found that the degree of dissolution of the radiator parts during brazing varied from 181 TP3T to 681 TP3T. Under the strong heating profile, erosion in some areas of the brazed joints can even lead to the destruction of thin-walled cooling fins. This indicates that excessive dissolution can have a serious negative impact on joint performance. Therefore, the conflicting needs of joint formation and substrate preservation must be balanced during process design.

2.2 Control of interfacial reactions in welding of dissimilar materials
When welding dissimilar materials, complex elemental interdiffusion and chemical reactions occur at the interface to form intermetallic compound layers. In contact reaction brazing of aluminium alloys with stainless steel, the use of Cu as an intermediate layer results in the formation of a composite structure consisting of Fe2Al5, FeAl3 intermetallic compounds and Cu-Al intermetallic compounds at the interface on the stainless steel side.

The thickness of the intermetallic compound layer at the interface increases with increasing holding time, while the width of the eutectic organisation gradually decreases. It is worth noting that the dissolution of the intermediate reaction layer Cu is very rapid, a fast process measured in seconds. This rapid dissolution behaviour puts extreme demands on the process control, requiring precise control of the heat input and action time.

3 Welding Quality Management and Performance Assessment
3.1 Total Quality Management System
The establishment of a comprehensive welding quality management system is the key to ensuring stable joint performance. This system should cover design control, process verification, online monitoring and final inspection and other links. For key structural components, it is also necessary to establish a full-process traceability system from the raw material into the warehouse to the product factory.

Quality control needs to focus on weld appearance, dimensional accuracy, mechanical properties and microstructure. For high-end manufacturing areas such as aerospace and automotive, special tests such as fatigue performance and fracture toughness are also required to assess the long-term reliability of joints under complex loads.

3.2 Non-destructive testing and performance prediction
Modern welding quality control increasingly relies on advanced non-destructive testing techniques such as X-ray inspection, ultrasonic testing and eddy current testing. These techniques can detect internal defects and assess the quality of joints without destroying the product.

Meanwhile, welding process simulation based on digital twin technology has become a powerful tool for predicting joint performance. By constructing a virtual model that can dynamically simulate the mechanical response of cutting, the researchers have improved the prediction accuracy by 15%, which not only reduces material waste, but also shortens processing time. A similar approach can be used to optimise and predict the welding process.

4 Welding technology development trend and innovative application
4.1 Intelligent and Automated Welding
Welding technology is rapidly developing in the direction of intelligence and automation. Intelligent welding system monitors the welding process in real time through multi-sensor information fusion, automatically adjusts the parameters, and ensures the consistency of joint quality. For example, the weld tracking system based on machine vision can automatically identify the position of the weld and compensate for assembly errors.

Robotic welding workstations and flexible welding lines have become standard in large manufacturing organisations, significantly improving productivity and stability. These systems typically integrate welding power sources, motion control, sensing monitoring and data analysis modules, enabling digital management of the welding process.

4.2 Welding Challenges of New Materials and Structures
With the continuous emergence of new materials, welding technology faces new challenges. Materials such as high-strength steels, aluminium alloys, magnesium alloys and composites have vastly different physico-chemical properties, requiring the development of special welding processes and filler materials.

Emerging technologies such as stir friction rivet welding show unique advantages when it comes to joining dissimilar materials. This technology has successfully achieved high-quality joining of aluminium alloys to steel through a combination of mechanical locking and finite metallurgical bonding. Studies have shown that the formation of harmful intermetallic compounds can be reduced and joint performance improved by surface plating with Zn or the addition of Zn elements.

4.3 Green Welding and Sustainable Development
The environmentalisation and energy saving of welding technology is another important development trend. By optimising process parameters, reducing energy consumption and material waste, and developing welding materials with low fumes and harmful gases, the environmental impact of the welding process can be significantly reduced.

soldredThe lightweight design of structures also makes a direct contribution to energy saving and emission reduction. For example, in automobile manufacturing, by adopting a hybrid structure of high-strength steel and aluminium alloy and combining it with advanced joining technologies, it is possible to reduce the weight of the body and fuel consumption while ensuring safety.

dissolutionCritical role of phenomena in welding and riveting processes and control strategies
1 Understanding the phenomenon of dissolution and its importance in joining materials
The phenomenon of dissolution is a fundamental and critical physico-chemical process in welding and riveting. It refers to the process of melting, mutual fusion and diffusion of base metal, filler metal or brazing material at the interface under the action of a heat source. This phenomenon directly affects the formation quality, microstructure and mechanical properties of the joint. Whether it is the traditional fusion welding, brazing, or the emerging stir friction riveting welding, the control of the dissolution process is the core link to ensure the performance of the joint.

In the case of stir friction rivet welding of aluminium alloys to steel, for example, the frictional heat generated by the rotation of the rivets during the joining process softens the aluminium alloy and produces a plastic flow that fills the prefabricated holes. During this process, a certain degree of elemental interdiffusion occurs at the interface, and even intermetallic compounds are formed. Similarly, during brazing, the rate and degree of dissolution of the base material has a decisive influence on the weld organisation and properties. Therefore, in-depth understanding and precise control of the dissolution process is of great significance for optimising the welding and riveting process, improving the reliability of the joints and prolonging the life of the components.

2 Typical dissolution processes and interfacial reactions in welding and riveting
2.1 Dissolution behaviour of base materials in brazing
During the brazing process, when the liquid brazing material comes into contact with the base metal, dissolution of the base material into the liquid brazing material occurs. This dissolution process is a complex physicochemical process, the rate and extent of which is influenced by a number of factors. It has been shown that brazing temperature, holding time, and brazing material composition all significantly affect the amount of dissolution of the base metal.

For example, in the brazing of aluminium heat exchangers, the researchers found significant dissolution and erosion. By comparing three different brazing profiles (normal, heated and strongly heated), it was found that the degree of dissolution of the radiator components during brazing ranged from 181 TP3T to 681 TP3T. Under the strong heating profile, erosion in some areas of the brazed joints can even lead to the destruction of thin-walled cooling fins. This indicates that excessive dissolution can have a serious negative impact on joint performance.

2.2 Interfacial reactions in the joining of dissimilar materials
When joining dissimilar materials, such as aluminium alloys and steel, complex chemical reactions and elemental diffusion occur at the interface, resulting in the formation of intermetallic compounds. In stir friction riveting welding of aluminium alloys to steel, the interface is prone to the formation of FexAly (x<y) type intermetallic compounds such as Fe2Al5 and FeAl3, which are aluminium-rich intermetallic compounds that are usually detrimental to the performance of the joint.

Through TEM inspection and other means, the researchers observed intermetallic compounds such as Fe4Al13, flaky Fe2Al5, and diffusely distributed massive FeAl6 at the interface of stir friction rivet welding of aluminium alloys to steel. The type, thickness and distribution of these compounds directly determine the mechanical properties and failure behaviour of the joint.

3 Strategies and methods for controlling the dissolution phenomenon
3.1 Optimisation of process parameters
The primary method of controlling the dissolution phenomenon is to optimise the joining process parameters. Critical parameters such as temperature, time and pressure need to be precisely controlled to balance the conflicting demands of the degree of dissolution and the performance of the joint.

During TLP (Transitional Liquid Phase) joining and brazing, the degree of dissolution of the base material can be effectively managed by controlling the maximum temperature and holding time. For example, in liquid film dissolution diffusion welding of steel materials, the spray melting temperature has a significant effect on the joint organisation and mechanical properties. With the increase of spray melting temperature, the interface Ni, Fe atom mutual diffusion intensifies, and the thickness of the interface diffusion bonding layer increases. It was found that in the static mirror liquid film state of 700~800℃, excellent weld zone without white mouth and hardened organisation can be obtained.

3.2 Material design and surface treatment
Harmful dissolution and interfacial reactions can also be effectively controlled through rational material design and surface treatment. In the connection between aluminium alloy and steel, the formation of harmful Fe-Al intermetallic compounds can be reduced and the generation of Al-Zn intermetallic compounds can be promoted by surface plating of Zn, Zn-Al-Mg or addition of Zn elements, which can improve the performance of the joint.

In contact reaction brazing, the use of Cu as an intermediate layer connecting 6063 aluminium alloy with 1Cr18Ni9Ti stainless steel can change the interfacial reaction path to form a composite interfacial structure consisting of Fe2Al5, FeAl3 intermetallic compounds, and Cu-Al intermetallic compounds, which improves the joint properties.

3.3 Innovative connection technology applications
Emerging joining technologies, such as stir friction rivet welding, naturally control the extent of harmful dissolution through clever process design. In this technology, the combination of mechanical locking and limited metallurgical bonding ensures joint strength while avoiding the formation of excess harmful intermetallic compounds.

The joint form of stirred friction riveting welding is mainly divided into self-riveting stirred friction riveting welding and self-pierce rotary riveting. In self riveting stir friction rivet welding, the aluminium plate is generally placed on top and the steel plate is placed on the bottom, taking advantage of the lower softening temperature of the aluminium alloy and the better plastic flow, to fill the prefabricated holes in the lower steel plate under the action of frictional heat to form a rivet welded joint. This process naturally limits the degree of interfacial reaction by controlling the heat input.

4 dissolutionEffects of the phenomenon on joint performance and quality assessment
4.1 Microstructure-mechanical property correlation
The dissolution process directly affects the microstructural characteristics of the joint, which in turn determines its mechanical properties. In stirred friction rivet welded joints, the joint area can be divided into stirred zone (SZ) or welded block (WNZ), thermo-mechanically affected zone (TMAZ), plastic deformation metal flow zone (PDZ) or self-riveted zone (SRZ) according to the law of organisational evolution.

Compared with the matrix organisation, the SZ regional organisation is obviously refined, with the finest grains, which are fine equiaxial crystals; the PDZ regional organisation is obviously coarsened, but is still relatively small compared with the matrix; the TMAZ regional grains are refined and obviously deformed due to the influence of mechanical stirring. This gradient change in microstructure directly affects the hardness distribution and mechanical properties of the joint.

4.2 Joint Failure Analysis
Improper control of the dissolution process can lead to a variety of joint defects and failure modes. Over-dissolution may lead to erosion phenomena, such as the destruction of thin-walled elements seen in aluminium heat exchanger brazing, while under-dissolution may lead to incomplete bonding and reduced joint strength.

In stir friction rivet welding of aluminium alloys to steel, the type of intermetallic compounds formed at the interface is critical. It has been shown that the formation of Al-rich intermetallics (e.g. Fe2Al5 and FeAl3) negatively affects the interfacial bonding as well as the strength of the joints compared to the formation of Fe-rich intermetallics (e.g. FeAl, Fe3Al).

5 Future development trends and prospects
With the continuous emergence of new materials and structures, the control of dissolution phenomena in welding and riveting faces new challenges and opportunities. The trend of lightweight drives the demand for joining lightweight materials such as aluminium-magnesium alloys and high-strength steels, which puts forward higher requirements for dissimilar material joining technology.

In the future, through the combination of multi-scale simulation and in-situ experimental observation, the nature of the dissolution process can be understood more deeply, providing theoretical guidance for process optimisation. Meanwhile, the development of intelligent control technology will realise real-time monitoring and precise control of the dissolution phenomenon in the joining process, further improving the stability and reliability of the quality of welded and riveted joints.