PDR Vehicle Panel Metallurgy & Body Structure 2

Question 1

Which type of vehicle panel construction most commonly uses a sandwich of two steel skins bonded to a core material?

Accepted Answer

Composite or laminated panel construction

Answer

Monocoque construction

Answer

Unibody roll-formed panels

Answer

Hydroformed structural rails

Question 2

A technician notices that a hood panel has a distinctly different 'push feel' than expected — spongy rather than firm. This most likely indicates:

Accepted Answer

The panel is a bonded composite or has delaminated inner layers

Answer

The panel is aluminum instead of steel

Answer

The metal has been over-hardened by the sun

Answer

The dent is too shallow to feel resistance

Question 3

Why is heat application (e.g., heat gun or heat lamp) sometimes used before PDR on aluminum panels?

Accepted Answer

To temporarily restore ductility and reduce work-hardening effects, making the metal more workable

Answer

To make the paint softer for polishing

Answer

To cause the aluminum to expand and self-repair

Answer

To magnetize the aluminum surface for tool adhesion

Question 4

The 'grain direction' of a metal panel is most relevant to PDR because:

Accepted Answer

Working against the grain can cause micro-tears, while working with the grain allows smoother metal movement

Answer

It determines the panel's color uniformity

Answer

Grain direction only matters for fiberglass panels

Answer

Panels rolled in one direction are lighter than bi-directional rolled panels

Question 5

Which term describes the permanent deformation zone of a metal panel where it has been stretched beyond its elastic limit?

Accepted Answer

Plastic deformation zone

Answer

Elastic deformation zone

Answer

Tensile recovery zone

Answer

Compression rebound area

Question 6

Dual-phase steel (DP steel) used in modern body panels differs from mild steel primarily in that it:

Accepted Answer

Has a microstructure combining ferrite and martensite phases, giving it high strength with better formability than UHSS

Answer

Contains two coats of factory paint

Answer

Is made from two layers of mild steel welded together

Answer

Is always thicker than single-phase steel panels

Question 7

When a PDR technician observes 'stress whitening' in a dark-painted panel after working a dent, this typically indicates:

Accepted Answer

Micro-cracking or excessive stretching of the paint layer due to over-manipulation of the metal

Answer

Successful repair with paint still intact

Answer

Normal oxidation of the clear coat during repair

Answer

Glue residue from a pull tab left on the surface