Metallography

Metallography and its importance

Metallography is a laboratory examination that analyzes the internal structure of metals and alloys. With the aid of special preparation techniques using an optical microscope, the microstructure, i.e. the arrangement of crystallites and inclusions, can be made visible. The microstructure of the material has a significant influence on the properties of the metal, such as its strength, toughness, machinability and corrosion resistance.

Metallography therefore plays an important role in quality control, defect analysis, material development and basic scientific research.

Processes of metallographic examination:

The “inner values” of the component can be determined by metallographic examination.

After the sample has been removed from the component, the microsection is prepared.

To create a macro finish on steels, grinding is carried out at grinding levels 120, 320, 500 and 1200. This creates a polished surface.

The next step is preparation by etching. Alcoholic nitric acid (unalloyed steels) or Adler etchant (high-alloy steels) are primarily used to see the weld seam and the heat-affected zone.

By selecting additional etching agents, further microstructural states can be visualized, e.g:

The following information can be obtained by metallographic examination:

Metallographic investigations are indispensable in materials science and quality control: the analysis of the internal structures and properties of metallic materials is of crucial importance for the evaluation and optimization of materials. In metallography, microstructures are among the most important methods of investigation:

Relevant investigations of the error analysis are:

Investigations in the field of heat treatment effects include:

The investigations of the manufacturing process include:

In the field of material identification, alloy determination is used to analyze the microstructure and phases of a material.

Which materials can be examined metallographically?

The most important group of materials for metallographic investigations are metals and alloys:

Finally, metallographic examinations of thin layers are also important:

Which methods of sample preparation are used in metallography?

Sample preparation is a crucial process step in metallography. The material is prepared for microscopic examination in such a way that a representative surface is available, which makes the inner structure of the material visible.

The most important methods include grinding, polishing, sample fixing and etching. For example, etching is used in metallography as a method of sample preparation for aluminum. For sample fixation, cold mounting is a frequently used method in metallography.

In addition to grinding in metallography, other processes include ion grinding for particularly sensitive materials or fine structures and ultrasonic polishing for very smooth surfaces.

Which microscopy techniques are used in metallography?

Light microscopy is a frequently used technique in metallography. Several forms of light microscopy are available:

These techniques are used in the field of electron microscopy:

Other metallographic techniques include

What types of microstructures can be analyzed by metallography?

These are the most important types of microstructures that can be analyzed in metallography:

Grain size and structure
Phases
Inclusions
Phase conversion
Defects
Deformation structures
Corrosion products

How long does a metallographic examination take?

The duration of a metallographic examination depends on many factors and can vary greatly. Among other things, the duration depends on these factors:

Simple metallographic examinations can be carried out within one day. Complex samples or extensive examinations can take several weeks.

What significance does metallography have for quality assurance in production?

Metallography plays a decisive role in the quality assurance of manufacturing processes. In concrete terms, this means for quality assurance that metallography makes an indispensable contribution to process optimization, error prevention and material selection. Legal aspects must also be taken into account, as many customers require metallographic examinations to meet quality norms and standards.

Does BLS Lasertechnology offer metallographic examinations as a service?

BLS Lasertechnology GmbH operates its own measuring laboratory with metallography laboratory for quality assurance. The BLS quality management system is certified to ISO 9001, DIN EN ISO 3834-2 and DIN 2303, among others, and aims to guarantee compliance with the highest quality standards and first-class results in laser material processing in all areas.

The metallography measuring laboratory is available exclusively for quality monitoring of prototype and series production.

What equipment is used in BLS Lasertechnology's in-house laboratory for ongoing quality controls?

Measuring laboratory:

Zeiss 3D coordinate measuring machine (CMM Contura)
Vertical length measuring device TESA Micro-Hite MH 900
Diavite DH-8 roughness meter
Thermal imaging camera
Leptoscope for determining coating thickness

Metallography laboratory:

Wet cutting grinder for sampling
Wet grinding machines for sample preparation to the desired grinding level
Various molds for cold mounting of ground specimens
Reflected light microscope (up to 250x magnification) for evaluating sections
Semi-automatic hardness testing system HV1 & HV10

The evaluation is always carried out on macrosections.

Over 35 years of experience and the trust of
more than 500 customers speak for us.

Customised solutions

BLS Lasertechnology manufactures customised solutions at the highest level. The BLS team works closely with its customers to develop the optimum laser application.

Flexibility

The adaptive use of resources enables a high degree of flexibility in production and deliveries at short notice.

Know-how

With over 35 years of laser experience, the BLS team offers exceptional expertise in laser processing. BLS customers also have access to experts in materials science, fixture construction and machine technology.

High performance

A powerful and broad range of machines (up to 12 KW laser power) with different laser sources (CO2 to solid-state) enable the optimum setup for every customer application.

What added value does metallographic examination offer in the following areas?

Thanks to our in-house laboratory, tests can be carried out during production, thus ensuring short throughput times.

Metallographic investigations play a fundamental role in quality assurance and process optimization in the fields of laser welding, laser cutting, laser hardening and laser cladding.

For laser welding, metallographic examinations enable the evaluation of the weld seam geometry, the weld penetration and the mixing zone. In addition, stresses and distortions can be examined and pore formation and cracking analyzed.

In laser cutting, examinations allow the quality of the cut surface, the heat-affected zone and burr formation to be analyzed. Hardening and stresses can also be assessed.

In the field of laser hardening, the hardening depth, hardness distribution and microstructure formation can be determined. In addition, metallographic examinations allow cracks and distortion to be analyzed.

In laser cladding, the tests make it possible to evaluate the adhesive strength, porosity and mixing zone. In addition, the adhesion between the base material and the weld deposit can be analyzed.

What else should I know about metallography
at the BLS?

BLS Lasertechnology GmbH is an owner-managed company with many years of expertise in laser processing. Our team of experienced employees has extensive know-how in the field of laser material processing of metal components. In laser welding and laser cladding in particular, we can call ourselves leading experts for complex orders.

Quality in laser processing is a central component of our corporate philosophy. In addition to the measuring laboratory with included metallography laboratory, we have an ISO 9001-certified quality management system for constant compliance with the highest quality standards and the achievement of first-class results in laser material processing.

Do you need high-quality, reliable and punctual laser processing of metal components?