A Nondestructive Evaluation Method: Measuring the Fixed Strength of Spot-Welded Joint Points by Surface Electrical...

Area of Science:

• Materials Science
• Mechanical Engineering
• Non-Destructive Testing

Background:

• Spot-welding is crucial for automotive structural integrity using zinc-plated steel.
• Traditional destructive testing methods for weld strength are costly and time-consuming.
• A need exists for efficient, non-destructive evaluation techniques for spot-welded joints.

Purpose of the Study:

• To propose and validate a nondestructive method for evaluating the fixed strength of spot-welded joints.
• To utilize surface electrical resistance measurements for assessing weld quality.
• To correlate electrical resistance with key mechanical properties like nugget diameter and tensile strength.

Main Methods:

• Development of a direct current nugget-tester and specialized probes.
• Measurement of relative decrease in surface electrical resistance (α).
• Estimation of nugget diameter using resistance variation (R_Quota) and corona bond area.

Main Results:

• The proposed method effectively evaluates fixed strength without damaging the material.
• Surface electrical resistance measurements correlate with nugget diameter and tensile strength.
• The method accounts for the influence of the corona bond on resistance readings.

Conclusions:

• Nondestructive evaluation of spot-welded joint strength is feasible using surface electrical resistance.
• This method offers a cost-effective and time-efficient alternative to destructive testing.
• The technique is applicable to zinc-plated steel, a common automotive material.