One Eighty is SANAS and ISO accredited for materials testing and is the most widely scoped materials testing laboratory in South Africa
In order to provide this service various routine metallurgical and materials tests are required according to detailed codes and standards. One Eighty is ISO 17025 accredited by SANAS and is able to provide these test certificates for a wide range of metallurgical and materials tests that mitigate risk and guarantee product quality.
Typical industry problems in this field include:
- Urgency of PQR/Positive Material Identification tests
- Tests sometimes fail and contingency plans are not in place
- Test schedule needs to be worked out based on codes, standards.
One Eighty’s laboratory is ISO-accredited to run all the relevant tests. The laboratory is run and assisted by qualified technicians and engineers. One Eighty’s engineers are solution-focused and able to find solutions for any problems, having extensive experience and expertise for all engineering materials. One Eighty offers complete WPQR testing.
The benefit of using One Eighty for materials testing include:
- Quick turnaround time.
- Solution development for any unforeseen material related problems.
- Assistance with any QA/QC requirements offered.
- Liaison with third party inspectors
- Tensile Testing
- Charpy Impact Testing
- Microstructural Investigation
- Micro-hardness Testing
- Macro-hardness Testing
- Corrosion Testing
- Bend Testing
- Composition Measurements
- EDS Analysis
- Galvanising Evaluation
- Ferrite Content Measurement
- Inclusion Content & Characterisation
- Polymer Identification
- Scanning Electron Microscopy
- Stereo Microscope
- Wear Particle Analysis
- Wear Testing
A tension test or tensile test provides a large amount of information about a material. A sample is machined from a plate or pipe section or round bar, or an actual part. The sample is placed in the grips and pulled apart at a controlled rate. During this process, the elongation of the material on a micro scale is measured against the required load to cause such a degree of deflection.
This graph is plotted and converted to stress versus strain data. From this graph the so called yield point, ultimate tensile strength, elongation to failure can be determined. The yield strength tells us what the load the material can take before it will buckle or distort. The ultimate tensile strength will tell us what load is required to cause rupture and failure or fracture of the material. The change in load between the yield and the UTS tells us how much load the material can take from when it starts to deform till when it fails completely. The amount of elongation to failure is the materials resistance to fast catastrophic fracture. All of these parameters need to be determined for materials for different reasons. The graph shows an example of a graph that is created by a tensile test.
For example this information is generated as part of the weld procedure qualification record testing. In such cases the test should not fail in the weld material, depending on the weld procedure code that is used.
The impact test requires a rectangular sample which is machined out either a welded plate or from a piece of material to be investigated. A notch is cut out of the sample and then it is placed in the machine. A hammer is applied to the sample in the area of the notch, and the sample fractures. The energy required to cause fracture is measured.
Tests are conducted at different temperatures from room temperature up to as low as -100°C. This is because steels can become brittle at low temperatures. After welding, brittle phases may be present in the weld. A test at low temperature will reveal if these phases are present.
The impact test is also used to re-grade material and is not only used for weld procedure qualification (WPQ) records.
The appearance of the fracture surface after impact gives a wealth of information about the material. A brittle material shows a flat smooth fracture surface compared to a ductile surface which has shear lips and is distorted.
We can also use charpy impact testing to identify other brittle failure mechanisms like hydrogen embrittlement for example.
Like the structure of a snow flake, every material has a characteristic structure. So much information can be gained from an engineering material by examining and understanding its microstructure. The relationship between mechanical properties and microstructure is the core of metallurgical engineering.
Microstructures can be designed. A material can be heat treated or processed so as to create a specific microstructure that the metallurgist knows will provide the right strength, or ductility properties. In the olden days of black smiths, the properties of steels were manipulated by heating the metal. Now days a more scientific understanding allows a metallurgist to literally design a microstructure. Whether this is a quench and tempered mild steel which resulted in a structure called martensite, or a normalised steel which results in a ferrite/pearlite structure.
For manufacturing to advance to the demanding needs of clients, the expertise of a metallurgist are critical. Materials can be manipulated to provide the required material properties through processing. Likewise, if an understanding of processing (rolling, forging, welding, forming) are not properly understood, it is easy to create an undesirable microstructure, which could result in failure of the material.
All engineering materials have some kind of microstructure not just metallic materials. Ceramics also have grains, and inclusions, pores or impurities. Likewise composite materials also have a structure related to the distribution of fibres or fillers and their pattern in the matrix material.
One Eighty has two microscopes for structural evaluation, whether this is a “macro” for a weld procedure qualification record or for examination of the structure to 1000X. We have trained metallurgists that can properly and accurately interpret what they see in the microscope, and more importantly properly prepare the sample so that the correct structure can be observed.
Microhardness tests are the same as a macro hardness test. Our hardness tester has a range of loads allowing us to test very thin coatings through a section, or to measure very hard coatings. The micro hardness test is also used for hardness traverse testing through case hardened parts for example and this information is used to measure the case depth, which is of critical importance.
Macro hardness testing is used to measure the hardness of any material. We test metallic material with the Vickers scale, which is the most modern method for testing engineering materials.
We can convert this to any hardness scale as required by the client. Vickers is suitable for testing any hardness range and is the most versatile testing method. We have a range of test loads that allow us to measure very soft material as well as very hard materials. In the past Brinell would be used for testing soft material and Rockwell testing for hard materials. Now days with the wide range of loads that can be applied to the tester, both soft and hard materials can be tested.
We can also test the hardness of ceramic materials. We use the cracks that are measured from the indent to determine the fracture toughness of the material in MPa.m1/2 Hardness surveys are required for weld procedure qualification record (WPQ) testing where tests are conducted in the weld material and heat affected zone and parent material according to a prescribed array in the codes.
We can conduct a wide range of corrosion tests, but most commonly are asked to do the ASTM G 48 test. This is an accelerated pitting test. The client specifies the temperature of the bath, and we place the prepared sample in a FeCl2 solution for a period of time. The temperature is carefully controlled. After the test the sample is measured for mass loss. The sample is then inspected for pitting corrosion.
This test is typically required for weld procedure qualification testing on SAF 2205, a duplex stainless steel. It is also often required for the austentic grades such as AISI 304 and AISI 31 stainless.
We make use of this equipment for a wide range of accelerated corrosion tests in different solutions other than FeCl2.
Three point bend tests are required as part of a weld procedure qualification (WPQ) record. Bend test samples are machined through the root and the face of a weld as is required.
Bend testing involves making a sample which is flat and long, and bending it in a mandrel through 180°.
The bend surface is inspected for cracks, in order for the WPQ to pass there should be no cracks in the weld metal.
Bend testing is also used to test the strength of composite materials such as glass fibre re-inforced plastic or carbon fibre or Kevlar fibre composites.
Bend testing is also required for testing of wires and re-inforced steel bars.
Compositional analysis by spark emission is a very accurate method of measuring the composition of metals.
The surface of the material is sparked with high voltage which releases x-rays from the surface, resulting in a spectrum. The instrument detects these x-rays and then is able to determine the weight percent of each element in the material.
We use this to accurately measure the composition of steels, stainless steels, aluminium and its alloys, copper and its alloys, zinc and its alloys and cast irons. We can detect the light elements such as carbon phosphorous silicon and sulphur in all these alloys to four decimal places as well as all the metallic elements.
We have a hand held XRF which can non destructively test any material but has the limitation of testing the very light elements. However it can be used for on site PMI (positive material identification).
Energy Dispersive X-ray analysis is a method to test the composition of any substance or material using a scanning electron microscope. The electron beam is focussed on to the specimen so that x-rays are generated from the sample. The detector collects x-rays and from this information determines the levels of elements present in the substance or sample.
In stainless steel welds for example it is often required to measure the ferrite content in the weld metal. Ferrite is the body centred cubic form of iron which can form in welds due to welding methods and weld rod composition. There are usually limits set out by the codes for ferrite content in the weld material, and therefore the test is sometimes required for the weld procedure qualification record (WPQ) test.
In order to measure the ferrite content in a weld, a sample is prepared and polished for microstructural investigation. Several images are taken from the microstructure and then processed with image analysis software to determine the volume of ferrite in each of the images. This is then averaged to provide a result.
This process is similar to the wear particle analysis measurements, hence can also provide information about the size range and shape of the ferrite automatically.
This method can also be used for the measurement of inclusion contents in materials or for general phase analysis and also for porosity measurements in ceramics, or castings or sintered components.
Inclusion contents in steels, or porosity measurements can be made in a similar way to the measurement of ferrite content in welds.
In order to measure the inclusion content in a material a sample is prepared and polished for microstructural investigation. Several images are taken from the microstructure and then processed with image analysis software to determine the volume of ferrite in each of the images. This is then averaged to provide a result.
This process is similar to the wear particle analysis measurements, hence can also provide information about the size range and shape of the ferrite automatically.
This method can also be used for the measurement ferrite content in stainless steels or for general phase analysis and also for porosity measurements in ceramics, or castings or sintered components.
R-DE02-14-01 – Measurement of inclusions (oxides and sulphides) in cast iron from Scaw Metals Group – click on the link to view the report.
Polymers are the most versatile of all material with a broad range of applications such as food containers, clothing, bullet proof vests and orthopaedic devices. With an increasing demand for polymers, the need for their identification is rising accordingly.
One Eighty Engineering Solutions (Pty) Ltd (OEES) can conduct a full polymer which enables us to determine the different components of the polymeric material as well as their relative percentage. A series of tests was specifically devised by OEES in order to conduct a full reverse engineering on a polymeric sample.
The polymer identification test is the primary test that is conducted in conjunction with a polymer failure analysis or material selection. OEES not only identifies the type of polymer but also determine the specific grade of the material as well as the different additives or fillers present in the material. OEES is able to investigate the root cause for the failure of the polymer based structure and recommend a more suitable polymeric material based on different engineering considerations such as strength, chemical resistance, lifespan and cost.
Scanning Electron Microscopy is a microscopy method of looking at samples at very high magnifications using an electron beam. The beam scans the surface of the specimen, and in so doing causes electrons to be released from the sample. These electrons are collected and used to create an image. Magnifications of up to 100 000X can be achieved.
Imaging can be done in both secondary electron and backscattered electron mode. Backscattered electron mode allows contrast in the image on the basis of composition. Heavy elements like niobium will appear bright while light elements like silicon will appear dark. This is a very useful method for phase analysis in metallic materials.
Secondary electron mode creates topographic contrast. This is useful for analysing fracture surfaces to see if the failure was brittle or ductile, or as a result of fatigue if normal light microscopy methods cannot diagnose this.
Sometimes wear debris from a wear test should be characterised. This is required for debris produced during biomechanical testing for example. ASTM and ISO standards describe how this should be done.
The test provides information about the wear particles such as particle concentration, frequency, particle size, and shape information. This is presented as histograms of frequency versus particle size and shape for example.
Particle Analysis can also be used to characterise emission particles, and any other application where the size and shape of particles needs to be known. This can also have applications in the mining industry where the size and shape range of agglomerates or slurries of ores need to be known as this influences the performance of processing of the ore.
With current research being conducted on ceramic, metallic, polymeric and elastomeric devices, 6° of Freedom has developed custom techniques and protocols to conduct analysis on wear particles (debris) obtained from these devices following biomechanical fatigue testing and biomechanical wear testing. This pioneering work has established 6˚ Degrees of Freedom as an internationally recognised leader in this highly specialised field.
With major device manufacturers now conducting intensive research on both Phagocytosis and Pinocytosis, the accurate analysis and separation of wear particles (debris) has led to 6˚ Degrees of Freedom developing new protocols related to this ongoing research.
Wear refers to the erosion of a material when it is in sliding motion with the surface of a second material. The wear rate is usually determined in terms of the mass loss of the material over a period of time.
Wear testing is a key mechanical and biomedical test that helps predicting the lifespan of a material in a particular system. The results of the wear study is one of the key properties in selecting a material. For example in the orthopaedics industry the wear rate of the material should be as low as possible in order to prevent the accumulation of wear debris in the body.
There are several testing methods (for example ASTM standards) that describes the parameters of the test procedure for a specific material or system. The wear rates of different systems such as: metal-polymer, metal-metal and ceramic-polymer can be conducted at One Eighty (Pty) Ltd. The parameters such as load, frequency and aqueous medium can be altered according to the desired requirements.
One Eighty (Pty) Ltd currently possess 3 wear testers and is able to conduct the wear testing of 6 samples simultaneously. The wear tester at One Eighty (Pty) Ltd can conducted 99999 uninterrupted cycles while generated graphical data according to the specifications requested by t he client.