Laboratory

1. Microscopes
2. SEM / EDAX
3. Geometry measurements

1. Microscopes
Facilities to prepare samples for microscopic investigation, such as grinding, polishing and etching, are present. Materials can be embedded in a resin (under vacuum) or in a hot mounting press. Samples for microscopic examination cannot be larger than approximately 25 x 25 x 25 mm due to the dimensions of the sample cups for embedding. There are only limited means at HE Tubing to cut small samples out of a large object.

Stereomicroscope specifications:

• Zeiss Discovery V12
• Magnification up to 100x

Optical microscope:

• Zeiss Observer Z1
• Magnifications from 25x to 1000x

Both microscopes have a camera connected to a PC for live images and to take snapshots. With the AxioVision software image analysis can be performed.

Examples of microscopic investigations:

• Determine microstructure (determine different phases, effect of heat treatment)
• Determine the grain size of the microstructure (according to ASTM E112)
• Size and number of precipitates, inclusions or porosities in the material
• Determining the fraction of a phase (duplex stainless steel: ratio austenite/ferrite; coverage of a surface with a coating (based upon contrast differences)).
• Determine the presence of hydrogen cracking or other welding defects
• Determine the weld penetration depth

2. SEM / EDAX

Specifications:

• Zeiss EVO 40 Scanning Electron Microscope (SEM)
• Ametek EDAX Apollo X Energy Dispersive X-ray Analyzer (EDX)

With the aid of SEM analysis small samples can be investigated with magnifications of up to 20.000x. Because the SEM is also equipped with Energy Dispersive X-ray Analysis equipment, the composition of corrosion products or inclusions can be determined semi-quantitatively. For instance a differentiation can be made between particles of carbon steel, stainless steel, non ferrous alloys and non-metallic parts such as plastic or sand. Only elements heavier than carbon can be detected with this technique.

Examples of SEM / EDAX investigations:

• Semi quantitative analysis of inclusions or phases
• Analysis of particles found in e.g. oil or filters, by which means the origin of the particles can possibly be traced.
• Mapping of elements: how are certain elements distributed in the microstructure or near a porosity or inclusion
• Fracture surface analysis: with the aid of SEM analysis it can be determined what type of fracture has occurred: brittle fracture, ductile fracture or fatigue fracture. The accuracy of this determination is strongly dependent on the state of the fracture surface (fresh and clean or old and damaged or corroded).

3. Geometry measurements

Specifications:

• DeMeet 220, a video and multi-sensor measuring machine for general quality control
• Maximum dimensions of the object to be measured: 220 x 150 x 100 mm (xyz)
• In principle only suitable for 2D measurements, limited 3D measurements are possible
• Measurement resolution: 0.5 micrometer

With the aid of an automated system (CNC) it is possible to measure multiple (identical) samples in one run. For each new geometry first a measuring program needs to be written, which will be based upon the measurements and tolerances given on the drawing of the sample. The results are then directly compared with these values so it will become clear at a glance whether the measurements are within specification or not.

1. Tensile test machine
2. Surface roughness measurements

1. Tensile test machine
Specifications:

• Zwick//Roell Z050 with a load cell capacity of 20 kN
• Zwick testXpert II software
• Automatic determination of the elongation at fracture by means of an extensometer
  (makroXtens)

The tensile test is executed according to ISO 6892-1, either according to Method A (strain rate
controlled) or Method B (force controlled).
Common values that are determined:

• Tensile strength (R m )
• Yield stress (R eH ) / Proof stress (R p )
• Elongation after fracture (A)

Due to the limited capacity of the tensile test machine, it is only suitable for materials with a relatively
low strength, such as aluminium, or for relatively small test specimens.

2. Surface roughness measurements
Specifications:

• Mitutoyo Surftest SJ-410
• Machine meets ISO 1997 requirements
• Tolerance Ra: +0.1% of minimum value
• Tolerance Ry: +1.1% of minimum value

Maximum measuring length: 50 mm

1. Electrochemical testing
2. Accelerated corrosion testing

Electrochemical testing
Specifications:

• Gamry Potentiostat 600 with ECM8 Electrochemical Multiplexer
• DC105 DC Corrosion software (http://www.gamry.com/products/software/dc105-dc-corrosion-
  software/)

The following electrochemical tests can be executed:

• Determination of the corrosion potential of a metal in an electrolyte of choice (for example sea
  water or chlorinated water from a swimming pool)
• Galvanic testing: determine which metal acts as a cathode relative to the other metal, in an
  electrolyte of choice
• Determine Tafel Scan: Comprehensive kinetic parameters and corrosion rate measurements.

As the electrolyte can be chosen freely, the corrosion potential can be determined in any specific environment. When the standard galvanic series gives insufficient information, by using a certain electrolyte, you will get a more realistic view of the corrosion behaviour of different materials in that specific environment.

Accelerated corrosion testing
Specification:

• Singleton SCCH 26 corrosion chamber (inside dimensions: 300x120x120 cm)

Accelerated corrosion tests can be executed according to the following standards:

• ASTM B117 Salt Spray test
• ASTM G85-A3 SWAAT test (Seawater Acidified Test)

In agreement, it is also possible to execute corrosion tests which deviate from the given standards with respect to time or spray medium. The time to failure (leakage) for hollow samples can be determined exactly by means of pressurizing the samples up to a pressure of 7 bars, and registering the time of a pressure drop. Depending on the size of the samples, up to 16 samples can be connected to a pressure gauge at the same time.

1. Laboratory roll coater (single side)
2. Zinc layer thickness measurements

1. Laboratory roll coater
Specifications:

• Mathis Reverse Roll Coater Type BA-RRC
• Lambda Technology NIR Test Oven 

A roll coater to apply a precise thin coating layer to determine for example the adhesion, layer thickness or brazeability of the coating/substrate combination. The coating can be dried in air, by hot air or by NIR (Near Infra Red) radiation.

2. Zinc layer thickness measurements
Specifications:

• Oxford Instruments CMI 900 X-Ray Fluorescence coating thickness measurement equipment
• Calibrated zinc layers thickness on aluminium of up to 5 micrometer (35,7 g/m2)
• Range of zinc layer thickness on aluminium most often used: 0.70 – 1.68 micrometer (5-12 g/m2)

This machine can be used to determine the layer thickness of for example an applied zinc arc spray (ZAS) layer. When calibration samples are made available, also the layer thickness of other metals on different substrates can be measured.