On-site testing and replication as a metallurgical testing speciality

One Eighty is Africa’s most ISO 17025:2017 scoped materials and metallurgical testing laboratory. We specialise in a wide range of on-site materials and metallurgical testing and replication.

On-site materials and metallurgical testing and replication is required when a sample from the component cannot be cut and destructive testing is not possible, but there is still a need to characterize the metallurgical properties.

So how does the process of replication work?

The surface must be first ground to remove surface scale/rust/coatings before being polished to a mirror finish. Once a mirror surface is achieved, the test surface is then etched using the material-appropriate etchant, followed by applying the repliset paste. The paste is allowed to fully cure in 15min, then removed and stored for transport for further analysis at our laboratory. Using light-microscopy on the replicant sample, technicians are able to see the tested materials’ microstructure with such detail, as if the physical sample is being analysed under the microscope! This allows for in-depth non-destructive analysis of various equipment/components, without the need to physically destroy them in the process, apart from the ground and polished surface. Any surface features, or defects (such as surface cracks), that are present on the tested sample, will be clearly visible on replicant sample.

Some of the uses of the replicant method include, but not limited to, inspecting boilers to determine whether the shell or tubes have been adversely affected by significant heat input, resulting in the formation of bainite in the microstructure that may lead to catastrophic failure. Other examples include assessment of storage vessels, ship propellers, construction beams, and other me mechanical components.

Here is an example of the type of image we can achieve with our accredited method of replication.  This shows carbon steel in the quenched and tempered condition, as opposed to the normalized condition.  This is key information about the component that has been analysed.  This result indicates that the steel has high strength as opposed to lower strength in the normalized condition.

The resolution of the replicate is so good that we can image it using an electron microscope at very high magnification.

Replication is used to identify destructive mechanisms such as creep (fracture along the grain boundaries due to heat) and also the presence of stress corrosion cracking in stainless steel, without cutting a sample.  It can be used to identify sigma phase formation in duplex stainless steels which may have been exposed to heat that it is not designed for.

Replication together with on-site hardness testing and handheld XRF can enable to classification of a material grade so that the mechanical properties and other physical properties can be determined from the standards on these materials.

Replication is used therefore to identify the heat treatment condition of a material, or to identify a failure mechanism.

See One Eighty’s list of ISO 17025:2017-accredited materials and metallurgical tests and non-accredited metallurgical tests and advanced materials tests.