introduction

Non-destructive testings is a way to analyze materials for imperfection without destroying the metal.

Lets first look at some of the different kinds of imperfections
 
A discontinuity is a disruption of  imperfections in a material that may cause a weak point and could cause a potential failure.
Metals may be forged or cast which can cause a number of different discontinuities such as the following:

• Laps
• Bursts
• Cracks
• Hot tear
• Shrinkage Cavity
• Blow holes
• Porosity
  

Process Discontinuities may include:

• Grinding Cracks
• Heat Treating
  
• Explosive forming
• Fatigue Cracks

Welding Discontinuities which are the one of the most tested for can include the following:

• Crater Cracks
• Stress Cracks
• Porosity
• Slag Inclusion
• Lack of penetration
• Under cut
• Lack of Fusion

Some of the Non-destructive testing methods that are used to detect these imperfections are:

• Liquid Penetrate Testing
• Magnetic Particle Testing
• Ultrasonic Testing
• Eddy Current Testing
• Radiographic Testing