Struers Inc.

Westlake, OH, United States

Struers Inc.

Westlake, OH, United States
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Vander Voort G.F.,Struers Inc.
Materials Performance and Characterization | Year: 2016

Over the years, ASTM Committee E4 on metallography has conducted interlaboratory test programs to evaluate the precision and bias associated with measurements of microstructure using proposed and existing test methods. ASTM decided in the late 1970s that all test methods that generated numerical data must have a precision and bias section defining the repeatability and reproducibility of the method. Defining bias associated with a test method is difficult unless there is an absolute known value for the quantity being measured and this is not possible when microstructural features are being measured. This paper shows the results for an interlaboratory test using Method A, "worst-field" ratings of inclusions in steels using the original Plates I and III of ASTM E45, using Method C, a worst-field rating using Plate II; and, using Method D, a quantitative approach where every field is rated using Plates I and III. The results from nine people who were reported to be qualified, regular users of the method revealed consistent problems of misclassification of inclusion types and a wide range of severity ratings for each specimen. The test results using an image analyzer will be compared to that of the manual raters. © 2016 by ASTM International, 100 Barr Harbor Drive.


Vander Voort G.F.,Struers Inc.
Advanced Materials and Processes | Year: 2011

Metallographic examination is a key tool in the destructive examination of weldments, both as a process control tool and as a post-mortem examination of failed components. Cracks that can be detected in the weld nugget or in the heat-affected zone are described based on their location such as crater cracks, root cracks, and heat-affected zone cracks. Macroetched low-carbon structural steels is welded using either different protective gas atmospheres or different heat inputs showing the influence of these variables upon the shape of the weld nugget, the depth of weld penetration, and the depth of the heat-affected zones. Examining a welded joint requires cutting out one or more specimens to sample the structure of the weld, heat-affected zone, and adjacent base metal. A polished specimen, when etched using a suitable reagent for the alloy, reveals both the macrostructure and the microstructure.


Vander Voort G.F.,Struers Inc.
Materials Performance and Characterization | Year: 2013

The claim made by Li in 1995 and 2011 publications that the Jeffries planimetric method of determining grain size presented in ASTM E112, as well as in DIN 50601 (it is the standard for every national and international grain size test method and is described in every textbook on quantitative metallography), is wrong and produces biased grain size ratings when the counts are low is incorrect. Li based this statement upon theoretical considerations described by Saltykov, who proposed using rectangles for the planimetric method, rather than circles, to minimize bias at low counts of the number of grains inside the circle. Saltykov, however, did not publish actual test data to back up this proposition. The count levels mentioned are far below those recommended by ASTM E112 for these methods, but they could be encountered in manual measurements of the size of very coarse grains (which might be performed but is rarely done). Actual grain size measurements using both test circles and rectangles, with a very wide range of grains within the test figures and intersecting their borders, showed that the ASTM Jeffries planimetric and Hilliard single-circle intercept methods produced statistically identical measures of the ASTM grain size G down to count levels far below what is recommended-down to 30 for (ninside+0.5nintercepted) for the planimetric method and down to 20 grain boundary intersections (Pintersections) for the intercept method (well below the recommended minimums of 50 and 35, respectively). At levels below these limits, bias was small-mainly data scatter was observed at counts less than 10 for both methods. The Saltykov planimetric method using rectangles gave the best data, identical to the ASTM E112 data, with statistically identical grain size values down to 10, and it was bias free, but it also exhibited data scatter at counts less than 10. Li's counting method, however, produced more bias at low counts than any other method. His claims have no validity. His model did not evaluate the effect of varying the counting conditions, which was the basis of his claim about the creation of bias. Also, he did not do actual tests to prove that his model was valid and that his claim was correct. Models do not have any validity if they do not test the actual conditions and are not verified by actual experimental data. © 2013 by ASTM International.


Vander Voort G.F.,Stivers Inc. | Vander Voort G.F.,Struers Inc. | Fowler R.,Stivers Inc.
Advanced Materials and Processes | Year: 2012

Different trends observed for low-load Vickers hardness are due to visual perception problems of operators of where indent tips are, not a material problem. The macro Vickers test creates a smaller impression, so it is not as good at averaging inhomogenieties in metals as the Brinell test. However, macro Vickers tests on such specimens reveal more consistent hardness numbers as the test load is increased and the indent becomes larger. Macro Vickers is very good for testing the hardness of cold-rolled metals and heat treated steels. Because the shape of the Vickers indentation is geometrically similar at all test loads, the HV value is constant within statistical precision over a very wide test load range as long as the test specimen is reasonably homogeneous. Specimen preparation for microindentation hardness testing is not a trivial matter, and becomes more critical as the applied force decreases. Specimen preparation for macro Vickers testing is less critical as the load increases.


Vander Voort G.F.,Struers Inc.
Advanced Materials and Processes | Year: 2012

George F Vander Voort explains how he was recently asked by Eric Gehringer, an associate producer at Hoggard Films in Boulder, Cob., to examine a lampshade frame to determine when and where it was made. Eric was hired by National Geographic to do a documentary film about the lampshade found in a damaged, abandoned house in the 9th Ward of New Orleans, destroyed by Hurricane Katrina. The initial examination of the lampshade was to take place at Aston Metallurgical, an independent laboratory located in Wheeling, Illinois, starting with cutting a section containing a small portion of the wire running from the bottom hoop to where it was welded to the ring that sits around the light bulb. Steels used for the ring and the wire are not modern steels, but typical of those made prior to WW II. These steels were heavily killed with aluminum, but without a Si addition. Prior to WWII, it was well known that Al was a much more effective deoxidizer than Si.


Although some publications have claimed that mechanical specimen preparation is inadequate for producing damage-free specimens for EBSD, this is certainly not true. Our methods have concentrated upon producing the best possible surfaces using an automated grinder-polisher with standard consumable products in a reasonable amount of time and at low cost Furthermore, these methods are highly reproducible as demonstrated by extensive tests on many metals and alloys from aluminum to zirconium Success depends first, and foremost, upon limiting cutting damage by using the proper blade and cutter Next, commence grinding with the finest abrasive that will remove the cutting damage in a reasonable time and make all of the specimens in the holder co-planar. Polishing is done in counter rotation with a low holder rotational speed to keep the cloth as uniformly covered with abrasive and lubricant as possible. The grinding and polishing steps must keep the surface perfectly flat for best results. After the final polish, a general purpose etch can be applied, with the specimens in the holder, to evaluate the success of the preparation and determine what the structure is. Then, remove the etched surface by repeating the final step but with about half the required time Preparation procedures are influenced by the crystal structure of the specimen. Face-centered cubic specimens will always exhibit more damage from each step than less ductile HCP and BCC metals and alloys. © Carl Hanser Verlag, München.


Decarburization is detrimental to the wear life and fatigue life of steel heat-treated components. Decarburization occurs when carbon atoms at the steel surface interact with the furnace atmosphere and are removed from the steel as a gaseous phase. If the surface hardness is below some predetermined limit, which varies with grade, then a microstructural examination is required. Chemical analysis of carbon on incremental turnings (or millings) can be performed, although this is more applicable to research than production. Metallographic rating of decarburization depth requires properly prepared specimens with good edge retention. This can easily be achieved with modern equipment and is reasonably fast. Microindentation hardness traverses are excellent for defining the maximum affected depth (MAD). The free-ferrite depth (FFD) is easily observed by light microscopy and adequate inspection of the periphery is needed to detect the deepest amount present.


Struers Inc., Cleveland, Ohio, introduces its new LaboSystem, a modular polishing system offering a choice of three LaboPol polishers, three LaboForce specimen movers, and two LaboDosers. Designed for reliability and speed, all LaboSystem products have been tested for more than 40,000 cycles. Short preparation time is essential for productivity, and the system makes it easy to switch from a 250-mm disk to a 300-mm disk, which means 44% increased surface area, faster processing time, and more room for larger samples. The LaboPol is made of corrosion-resistant, robust, and impact-proof materials. It features a cast aluminum block that serves as a rigid backbone, providing a robust base for the control panel and specimen mover. A modular design enabling seven different configurations allows adapting or upgrading according to developing needs. The elevated control panel is located to avoid accidental speed change or damage by large samples. An integrated LED light provides the best possible view of the preparation area. The LaboPol features an emergency stop that immediately halts all moving parts, and a splash ring to prevent fingers or specimens from getting trapped between the cabinet and the disc.

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