Porosity Testing

Porosity is a measure of the void spaces in a casting material. Porosity causes a casting to leak and makes it unusable for holding pressure.

The porosity of the coating refers to the small channels from the coating surface to the base metal. The porosity of the coating reflects the density of the coating surface, and it directly affects the tensile strength, elasticity, resistance to corrosion, damping capacity, and other mechanical characteristics of the protective coating. The measurement of porosity is an important index to measure the quality of coating and evaluate whether the coating performance meet the specific requirements.

Porosity can also be found in the weld metal due to the freezing in of gas released from the weld pool as it solidifies. Porosity is present in the weld metals in the following forms:

• Distributed porosity: Found as fine pores throughout the weld bead.
• Surface breaking pores: A large amount of distributed porosity
• Wormholes: Elongated pores producing a herring bone appearance on the radiograph
• Crater pipe: Formed during the final solidification of the weld pool

Other materials with porosity susceptibility include C-Mn steel, stainless steel, aluminium and alloys, copper and alloys, nickel and alloys.

STEMart can carry out a series of porosity testing on various metal products.

Test Methods

• Chemical testing
  • Impregnation test: iron reagent test, acid copper sulfate solution test, cadmium sulfate test, hydrogen peroxide test, sodium chloride / hydrogen peroxide solution test, etc.
  • Solvent spreading test: iron reagent test
  • Filter paper test: iron reagent test, organic indicator test
  • Salt spray test: neutral salt spray test, acetic acid salt spray test
  • Gas atmosphere test: NH₃, SO₂, H₂S, HNO₃
• Electrochemical method
  • Anode treatment: iron reagent test
  • Electrolytic imaging test: photographic paper test, gypsum indentation test, colloidal medium test, analytical determination
• Physical method
  • Optical method
  • High voltage or high frequency method
• Non-destructive testing
  • Liquid penetrant testing
  • Magnetic particle inspection
  • Ultrasonic testing
  • Radiographic testing

For more information about our porosity testing services, please contact us.