Question

The welding process commonly used for fabricating tailor-welded blanks of dissimilar thickness for automotive applications is

• A. arc welding
• B. laser welding
• C. gas welding
• D. friction welding

Hint:

When you see "tailor-welded blanks" or "automotive sheet metal joining," immediately think of high-energy density processes like Laser Beam Welding for its precision, speed, and low distortion.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to identify the most suitable welding process for creating tailor-welded blanks (TWBs), which are common in the automotive industry and often involve joining sheets of different thicknesses or materials.
Step 2: Detailed Explanation:
Tailor-welded blanks are made by welding flat sheets of metal together before they are stamped into their final shape (e.g., a car door panel). The welding process for this application must have specific characteristics:

• Low Heat Input and Narrow Heat-Affected Zone (HAZ): To minimize distortion and maintain the mechanical properties of the parent metals.
• High Welding Speed: For mass production efficiency.
• High-Quality Weld: The weld seam must be strong and ductile enough to withstand the subsequent stamping/forming process.

Let's analyze the options based on these requirements:

• Arc welding (e.g., MIG, TIG): These processes have a relatively high heat input and create a wider HAZ, which can lead to distortion and reduce the formability of the blank.
• Laser welding (specifically Laser Beam Welding - LBW): This process uses a highly concentrated energy source. It is characterized by very high welding speeds, extremely low heat input, a very narrow weld bead, and a minimal HAZ. These properties make it the ideal and most commonly used process for fabricating TWBs, as it produces a high-quality weld with minimal distortion that performs well during forming.
• Gas welding (e.g., Oxy-acetylene): This process has very low energy density and extremely high heat input, leading to massive distortion and a wide HAZ. It is completely unsuitable for this application.
• Friction welding: This is a solid-state welding process that produces high-quality welds. However, it is typically used to join components with circular cross-sections (like rods and pipes) and is not suitable for welding large, flat sheets together.

Step 3: Final Answer:
Laser welding is the preferred method for fabricating tailor-welded blanks due to its high speed, low heat input, and the high quality of the resulting weld.