I-CAR Welding Techniques and Processes

Question 1

Which welding process is most commonly specified by vehicle manufacturers for structural collision repair?

Accepted Answer

Squeeze-type resistance spot welding (STRSW)

Answer

Squeeze-type resistance spot welding (STRSW) is the OEM-preferred process because it most closely replicates the factory spot welds used in vehicle assembly.

Question 2

When performing MIG plug welds as a substitute for factory spot welds, what drill bit size is typically used to prepare the plug weld hole?

Accepted Answer

8 mm (5/16 inch)

Answer

An 8 mm (5/16 inch) hole is the standard size for MIG plug welds to ensure adequate weld nugget size matching factory spot welds.

Question 3

What is the primary reason oxyacetylene welding is generally prohibited on modern high-strength steel (HSS) structural components?

Accepted Answer

The heat-affected zone is too large and degrades HSS properties

Answer

Oxyacetylene welding creates an excessively large heat-affected zone that anneals and destroys the strength properties of high-strength steel.

Question 4

In MIG (GMAW) welding for collision repair, which shielding gas mixture is most widely recommended?

Accepted Answer

75% argon / 25% CO2

Answer

A 75% argon / 25% CO2 mixture provides the optimal balance of arc stability, penetration, and spatter control for automotive steel welding.

Question 5

What does the term 'heat-affected zone' (HAZ) refer to in welding?

Accepted Answer

The region of base metal that was not melted but had its properties altered by welding heat

Answer

The HAZ is the area of base metal adjacent to the weld that was not melted but experienced temperatures high enough to change its microstructure and mechanical properties.

I-CAR - Inter-Industry Conference on Auto Collision Repair Certified Practice Test

I-CAR - Inter-Industry Conference on Auto Collision Repair Certified Practice Test

I-CAR Welding Techniques and Processes