The Importance of Quality Control in Welding Processes

Abraham Silva Hernández welcomes participants to the webinar on welding quality system. The presentation focuses on the American Welding Society's classification of welding processes and the welding quality system. Mauricio Tello will address queries in the live chat.

Welding processes are classified into three main types: fusion welding, solid-state welding, and brazing. Fusion welding involves both base metal and filler metal reaching a liquid state. Solid-state welding does not reach a liquid state, while brazing involves melting only the filler material. Various welding processes like GTAW, FCAW, and SAW are discussed.

Quality standards in welding, particularly the AWS specification 2.1, cover the qualification of procedures and welders. Specific processes like SMAW, GTAW, FCAW, and SAW have unique characteristics and requirements for ensuring quality welds.

Solid-state welding processes include friction welding, resistance spot welding, and friction stir welding. Each process has its standards for procedure qualification, operator qualification, and testing. Examples like RSWM, RSW, and FSW are highlighted for their specific applications and benefits.

The welding standards for friction stir welding include AWS D17.3 for qualification and quality testing in aluminum alloys for aerospace applications. Additionally, for resistance spot welding, standards like AWS D8.6.1 and AWS D8.6.2 are followed.

Certification and qualification in welding involve standards like AWS D1.1 for recommended practices, AWS D1.4 for quality system requirements in carbon steel resistance welding, and AWS D1.5 for qualifying resistance welding technicians.

The discussion includes an overview of welding processes such as brazing and soldering, where the material to be fused is the filler material. The difference lies in the melting temperature, influenced by the energy source used.

Various methods of fusing filler material are discussed, including torch, resistance, and induction heating. Each method has specific applications and temperature requirements for melting the filler material.

Controlling welding variables, from base material to cleaning methods, is crucial to avoid severe discontinuities like cracking. The three most critical welding defects are cracking, incomplete fusion, and incomplete penetration, as per AWS D3.0 standard.

The American Welding Society emphasizes the need for inspection before, during, and after welding to ensure quality. Before welding, it is crucial to assess the base metal's condition to prevent issues like contamination, which can lead to defects in the weld. For instance, welding titanium requires strict control of moisture and atmospheric oxygen to avoid hydrogen-induced cracking and brittle oxide formation. Similarly, welding oxidized or greasy steel can result in incomplete fusion or porosity.

During welding, it is essential to monitor electrical variables, welding speed, cleanliness between passes, and multi-pass welding for a sound joint. Controlling these factors ensures the quality and integrity of the weld during the process.

After welding, inspection focuses on the weld's appearance, final cleanliness, and potential post-weld heat treatment. Materials may require specific heat treatments based on their thermal history, affecting the welded joint's properties. Post-welding processes play a crucial role in ensuring the weld's longevity and performance.

The welding industry faces common challenges such as maintaining profitability, attracting new clients, technological advancements, and coping with national industrial scenarios. To thrive, companies must implement quality systems, documentation, technological improvements, and adapt to external factors like government changes, economic variables, and cost fluctuations in inputs and technology.

Implementing a well-executed welding quality control system helps in managing factors detrimental to companies such as excessive staff turnover, inadequate documentation of processes, inefficient equipment usage, and limited access to new market opportunities.

Excessive staff turnover can lead to a loss of critical knowledge and skills, hindering production continuity and requiring starting from scratch, impacting profitability and customer assurance.

Having comprehensive documentation of welding processes is crucial for ensuring control, meeting client requirements, and guaranteeing the quality of welded joints.

Using efficient welding equipment like the EFE S/A W or Flux Cort can significantly increase welding speed, depositing welds at a much faster rate compared to processes like shielded metal arc welding.

Limited market opportunities arise from a lack of documentation and qualifications, making it challenging to participate in tenders or bids that require specific documentation and skill certifications.

A well-implemented welding quality control system provides procedures, documentation, qualified welders, and skill evaluation records, enabling control over various aspects of the welding process.

In Mexico, widely used welding quality control systems include the Doble and ISO systems, with additional systems like the ASME, AWS, and IIW being less common but still relevant for specific applications and certifications.

The main quality system for welding in the country is the double S welding quality system. It consists of three key points: equipment verification, welding procedure qualification (WPS), and welder performance qualification (WPQ).

Equipment verification involves checking that the welding equipment is providing the correct values. For example, if the welding machine is set to 100 amperes, it should output this value within a 10% margin of error when tested with a calibrated multimeter.

After ensuring the equipment's reliability, the welding procedure qualification involves testing the welding process with specific parameters to validate the welding conditions. This process establishes a set of welding conditions known as the WPS.

Welder performance qualification includes testing the welder's ability to follow the established welding procedure. Once the welder successfully completes the required tests and inspections, an inspector issues a document certifying the welder's qualification.

Trazability is crucial in welding procedures, ensuring that all reports and qualifications are linked to each other. It is essential for welders to be referenced to a specific welding procedure to maintain standards and accountability.

Inspectors often put both their seal and signature on documents to prevent plagiarism. This practice is common to ensure authenticity and avoid unauthorized use of documents.

Various documents are applicable for qualifying procedures. One such document is the AW 2.1, which is used to qualify welder procedures and skills for general applications.

For example, if a furniture manufacturer needs to qualify procedures and welders for stainless steel, aluminum, or steel furniture, they may use the BE 2.1 document for procedures that do not fit into specific codes.

Welding for aircraft components like turbine repairs or turbofan tubes follows the ASME Section IX standards, specifically the ASME SFA 17-1 for inspection and quality criteria.

The AWS D1.1 is the structural welding code for steel, providing guidelines for qualifying procedures and welder skills specifically for steel structures within defined thickness ranges.

The key difference between codes like AWS D1.1 and documents like BE 2.1 lies in the comprehensive nature of codes, which include design considerations, inspection, procedure qualification, welder qualification, and repair sections, unlike more focused documents like BE 2.1.

Various specific welding documents are used, such as the AWS D15.1 for tank welding and locomotive applications, providing detailed guidelines for welding in those specific contexts.

The railway welding procedure involves specific documents such as the double S of 15.2 for rails. Any doubts regarding these documents can be addressed in the chat or email provided at the end of the presentation.

There are three levels of welding certification: Certified Senior Welding Inspector (SSW), Certified Welding Inspector (CW), and Certified Assistant Welding Inspector. The CW and SSW can qualify welding procedures.

The double UPS contains welding variable values like process, material, current, and speed, validated through mechanical tests, non-destructive testing, and other tests like bend tests and tension tests.

Qualification tests for welding procedures vary based on codes. For example, in ASME Sec. IX, besides bend and tension tests, volumetric non-destructive tests like ultrasonic and radiographic tests are required.

In welding procedures, essential variables are crucial as changing them may require recalibration of the procedure. Essential supplementary variables are important for impact testing and tenacity of welded joints.

In welding procedures, there are essential and non-essential variables. Essential variables are crucial for the procedure's impact, while non-essential variables can be changed without affecting the outcome. These distinctions are based on years of studies and numerous tests.

The welding process involves creating an electric arc to melt a solid wire, which is then deposited. In the case of a semi-automatic process like MWV (Micro Wire), the wire feed speed is controlled at the machine, making it semi-automated. Other processes range from manual control to fully automated, like robotic welding.

Welding processes can be manual, semi-automatic, or automated. Manual processes, like shielded metal arc welding, require direct control over electrode feed and application speed. Semi-automatic processes, like MWV, involve machine-controlled wire feed speed, making them semi-automated.

In welding procedures, the design of the joint is crucial. Different types of joints, such as butt joints, lap joints, corner joints, and edge joints, require specific welding techniques. For example, a fillet weld is commonly used for butt joints, providing strength and durability to the welded structure.

Welding procedure specifications can be customized to ensure proper understanding and application for welders. This includes considerations like backing material, root opening, and shoulder height, which are crucial for joint preparation. Different welding joints may require varying measurements and values to be specified in the procedure.

One key aspect of welding procedures is the qualification of weld sizes and thicknesses based on document specifications. Welders must adhere to set values and ranges for fillet weld and thickness sizes to ensure proper qualification. The document dictates the allowable ranges within which welders can work, ensuring consistency and quality.

In welding procedures, the specification of base materials is essential. For instance, using ASTM A36 steel, a low-carbon steel, falls under group M1 according to standard W2.1. This group includes low-carbon steels with minimal alloying elements, making them easier to weld. Welding procedures can be applied to any material within the same group as long as it meets thickness requirements.

Qualification tests for welding procedures involve specific parameters such as qualified thicknesses and fillet sizes. These tests are conducted to determine the appropriate ranges for welding processes. Adhering to these parameters is crucial to prevent issues like incomplete fusion or weld failure during service.

The qualification record contains values that are input into the code to determine the allowable ranges. These ranges are then used in the final recipe, which specifies the welding parameters for the welding process.

The welding procedure involves using filler metal, such as a 35 mils diameter AWS A5.18 classification ER70S-6 electrode. This electrode material has specific mechanical properties denoted by the '70' in its designation.

Argon and CO2 in a 75-25 ratio are used as shielding gases during the welding process to protect the molten weld pool from atmospheric contamination.

Preheating may be required based on the welding code, but in some cases, the process can be carried out at ambient temperature. Electrical variables like polarity, voltage, wire feed speed, and current play a crucial role in determining the heat input during welding.

The welding procedure qualification involves documenting data collected during welding, which is then used with the welding code to determine the specific welding parameters. The qualification record, along with the welding recipe and test results, forms the basis for welding operations.

Various tests such as tension tests, bend tests, macrographic tests, toughness tests, and corrosion tests are conducted to qualify a welding procedure. The type of tests conducted depends on the type of joint being welded.

Welding quality control procedures involve various tests such as tension, bend, macrography, and fracture tests to assess mechanical resistance, ductility, and fusion quality. Different types of welds require specific tests like liquid penetrant, micrography, hardness, and chemical analysis to ensure quality and integrity.

Non-destructive testing is crucial in welding quality control, requiring visual inspection before, during, and after welding. Tests like liquid penetrant, magnetic particles, ultrasonography, and industrial radiography are conducted based on applicable standards and specifications.

The welder qualification process involves evaluating the welder's skills through tests like bend tests and radiography. Essential variables for welder qualification include the welding process, base material, filler metal, thickness, diameter, position, and shielding gas.

The welding quality assurance system encompasses various aspects such as welding technologies, including arc welding, resistance welding, laser welding, and training in different welding processes like GMW, GTAW, and CMT. Additionally, it involves interpretation of codes and standards like ASME, AWS, and ISO.

The welding department has over 30 years of experience in arc welding, resistance welding, laser welding, and training in various welding processes. They also provide training in welding fundamentals, code interpretation, and metallurgy for industries like aerospace, railways, automotive, and more.

The speaker discusses the latest welding technologies, including laser welding and additive manufacturing. Mentioned processes like deposition of additive deposits with the GM double CMT process.

Quality control in welding ensures the control of electrical variables, machine variables, and the welding process itself. It also ensures the competence of welding operators through welder qualification testing.

Implementing a welding quality system allows for precise control of welding parameters, ensuring parts have the correct properties. It also helps in controlling variations that could affect the process and enables expansion as a supplier to industries requiring higher production volumes.

Having a welding quality system enables entry into various industries like automotive, structural, and aerospace by meeting their welding procedure requirements. It facilitates compliance with industry standards and specifications.

Contact details for inquiries related to welding processes, including metals like titanium, copper, aluminum, and various alloys. The speaker mentions working with different welding processes beyond arc welding, such as resistance welding and solid-state processes.

The webinar concludes with a thank you message to the audience. The video recording will be available on the YouTube channel for further reference. Viewers are encouraged to subscribe for more related content and follow the organization on social media for updates on upcoming webinars.