Macroetch & Sulfur Print Testing
With a long history of providing analytical services for the steel and metals industry, Clark Laboratories has been providing Macro etching and Sulphur printing services to steel producers for many years. Macro etching, also known as deep etching or chemical etching, is a non-destructive quality inspection to expose granular material segregation, cracks, voids, pinholes, porosity, or structural anomalies. Macro etching analysis can evaluate grain size and flow along with indication of overheating during
the steel casting process.
Along with the quality analysis features provided by Macro etching, the process can also be beneficial for essential maintenance for the steel casting process. By measuring certain voids or streaks,
calculations can be made to perform necessary maintenance of the casting process to improve the quality of casting. Clark Labs provides Macro Etching services in accordance with ASTM E340 and ASTM E381. The process involves cutting and cleaning the specimen to expose a clean surface. The specimen is then prepared with an acid or reagent for microstructural examination and then photographed at a high resolution. The photographs will show patterns of grains, voids, porosity, cracks, inclusions, segregation, banding and structural imperfections.
Sulfur printing, also known as Baumann Prints, measures the distribution of sulfides in steel. Sulfur
print test is a qualitative analysis and will reveal the details of the solidification pattern or flow of metal
from hot or cold working on the test specimen.
The process includes a prepared steel specimen freshly cut and cleaned to remove all scale, cutting oils, and other contaminants. Photographic paper is used to transfer the image of the embedded silver sulfide from the specimen. The photographic paper is soaked in a sulfuric acid, citric acid or acetic acid solution. The photographic paper is removed, washed in water and dried flat.
Sulfur printing complements Macro etching to provide additional evidence of homogeneity of a steel