Mechanical tests on welds

These specific tests on welds include longitudinal tensile tests, bend, hardness and impact tests. They can be performed according to ISO standard or ASME IX code.

Interpretation of test results or supplementary information can also be obtained through macroscopic and microscopic examinations of welds.

Application fields:

  • Qualification of welding procedures and operators
  • Production monitoring
  • Setting of welding parameters
  • Quality control

Longitudinal tensile test on welds

Bend test on welds

Hardness testing on welds

Impact test on welds

Macroscopic and microscopic examination of welds

 

Longitudinal tensile test on welds

Compared to tensile test on parent metal, this test on welds is used to determine the Ultimate Tensile Strength (UTS) of groove-weld joints. The position of the fracture is also recorded.

The cross joint strength is usually required to exceed the minimum specified UTS of the parent metal.

Equipment: hydraulic test machine up to 300kN

 

Bend test on welds

Bending test is a simple qualitative test that can be used to evaluate both the ductility and soundness of a material. This test uses a coupon that is bent in three points to a specified angle over a given radius.

The outside of the bend is extensively plastically deformed so that any defects in, or embrittlement of, the material will be revealed by the premature failure of the coupon. The bended sample is thus inspected for cracks on the outer surface.

 

Hardness testing on welds

Welding imposes a variety of thermal cycles at different locations on the base metal and can thus produce undesirably hard microstructures which are subject to cracking and brittle fracture. Hardness tests are carried out on welds to detect hardened areas in the weld or in the heat-affected zone.

Equipment: Hardness test machine for HV0.5, HV10, HV30

 

Impact test on welds

Impact tests are used to evaluate the toughness of welds. Toughness is measured by the amount of energy required to cause an item to fracture and fail.

This test involves striking a standard specimen with a controlled weight pendulum travelling at a set speed. The amount of energy absorbed in fracturing the test piece is measured and this gives an indication of the notch toughness of the test material.

A brittle material will absorb a small amount of energy when impact tested, a tough ductile metal a large amount of energy.

 

Macroscopic and microscopic examination of welds

A cross section of welded material is polished and etched for examination.

The examination (macro or microscopic, the latter corresponding to magnifications higher than 10x), reveals the procedure and quality of the weld through internal discontinuities, weld profile, weld passes and sequence. Porosity, lack of weld penetration, lack of fusion, poor weld profile and other important defects can be checked in accordance with the relevant welding standard.

Equipment: microscopic optical material (magnification from 2x to 500x at welding lab)