Structural integrity is an engineering focus that determines if a design is safe or creates risks of failure. For the safety of the public and our environment along with economic reasons, structural integrity is always under-evaluated by engineers.
Today we use machines in every part of our life from aircraft to mining equipment or computers to pipelines in our cities. Thus it’s essential to evaluate any product’s structural integrity and fatigue life.
Welding is a widespread process used in almost every industry to manufacture products. As with all other manufacturing processes welding methods must be improved to make parts that can handle stress and wear without breaking. If the concept and execution of the weld are done well the product will be safe and keep its structural integrity, as it should.
There are many advanced welding technologies that try to reduce the downside effects of welding on the material. While making industries more efficient, safety margins are getting tighter than ever.
This means that the initiatives are driven by the assessment of the structural stability of welded parts as well as the introduction of new technologies.
Basics of Welding Metals
Both metallurgy and welding have their roots in the Industrial Age and this was the first way that metals were joined together. Welding is a type of fabrication in which two or more pieces are joined by applying heat pressure or both and then allowed to cool as one solid piece. Typically metals are welded together and the resulting weld can be called a weldment.
Welding creates a permanent connection between the two components transforming separate parts into a whole. Welding is a high-heat method that melts the base metal which differs from brazing and soldering which do not melt the base metal. Most of the time by adding a filler material.
High-temperature heat makes a pool of liquid material called a “weld pool ” which cools to form a joint from the metal it’s joining. Heat and pressure can be used together or separately to make a weld.
Some types of joint configurations for welding are:
- Butt Joint
- T Joint
- Corner Joint
- Edge Joint
- Cruciform Joint
- Lap Joint
Welding is the most cost-effective method of joining components both in terms of raw materials and labour. Other mechanical assembly techniques involve installing fasteners (such as rivets or bolts) and the resulting mechanical assembly is typically heavier than its equivalent weldment.
Metallurgical Engineering and Welding
Metallurgical engineering focuses on the safe and efficient processing of metals. These engineers work on ensuring the safety of materials, developing sustainable processes, and investigating material failures. They also conduct tests and analyses to ensure materials can withstand extreme environments and protect their structural integrity.
Metallurgical processes can be used to change the microstructure and characteristics of welds. Melting and solidifying are essential steps because they are the sole means to make good joints when fusion welding. Segregation and diffusion processes happen at the same time as solidification. This leads to local compositional differences that affect both weldability and service performance.
Welding joints need the expertise of metallurgical engineers who are experts in the microstructure and properties of metals. Materials research design inspection are all integral parts of welding engineering. Using a highly certified and experienced Weld Engineer ensures the protection of structural assets.
Weld Quality and HAZ Transformations
The head affected zone (HAZ) is a part of the metal that hasn’t melted but has changed because it was exposed to high temperatures. The HAZ’s intensity and distribution are affected by material characteristics, heat output, and welding technique.
Due to the amount of these processes the microstructure and properties of weld metal HAZ and base metal can change a lot. Welds can get complicated stress patterns because of thermal expansion and contraction when heated and cooled. When these pressures cause a tensile strain greater than the material’s ductility cracks can form in the microstructure and properties of the weldment.
Welded connections often fail for the same reasons that have already been stated. In most structures made of metal failures like cracks fatigue and corrosion usually start at the places where metal pieces are welded together. In most cases, the HAZ region has weaker mechanical properties than the surrounding parent material.
So controlling the changes in the HAZ zone and making effective strategies that take these changes into account significantly affect the weld’s quality. The quality of the welds and by extension the structural stability of the welded sections can be determined by conducting various tests on this area.
Failure Analysis of Welded Structures
Structures are getting bigger and more complicated. They often have to withstand much harsher weather than they used to. Because these situations are so adverse, correct failure analysis is even more critical.
Engineers are often called in when welded parts break to figure out what went wrong. Failure analysis is the process of finding out why and how structural assemblies and test models break.
There are several reasons why welded links can fail:
- Weld Geometric Design
- Weld Process Parameters
- Material-Process Incompatibilities
- Weld Process Execution
Failure Analysis of Welded Structures can be as straightforward as a visual inspection with a light microscope or it can involve more complex techniques such as scanning electron microscopy (SEM) transmission electron microscopy (TEM) or electron backscatter diffraction (EBSD).
Expertise in metallurgy materials and field-engineering knowledge is as crucial as the methodologies and equipment used to conduct a failure study. It is also important to take attention to accurately evaluating FEA results if used for welded joints.
Conclusions
Welding will continue to be a popular way to make things because it is easy to assemble from individual components. However careful design and execution by expert welding engineers are required. Failure analysis and standards for preventing failure are essential for making good-quality items.
Modern inspection methods for weld zones and FEA methods have made it much faster to check structural stability. Welding design and structural analysis engineers form an experienced team that can anticipate and create weld designs, as well as organise procedures using frontal analysis.
A well-designed joint ensures the safety and cost-effectiveness of the structure. On the other hand, a poorly designed weld can cause catastrophic failures, especially in heavy-duty industries like mining or sensitive industries like aviation.
Trevilla Engineering are the experts in structural certification and design. Our clients rely on us to deliver the highest level of weldment and joint integrity.
Using a highly qualified and experienced Weld Engineer ensures that your most valuable resources are well protected.
