2 Ways We Streamline ASTM Standard Compliance in OLYMPUS Stream Software

By Dr. Norbert Radomski - 30 December, 2019

ASTM International standards have been adopted by government agencies and corporations around the world to support quality manufacturing and environmental safety.

Yet, standard practice procedures can involve repetitive inspection and measurement tasks that become tedious and time-consuming.

To tackle this challenge, our Custom Solutions Group (CSG) set up personalized workflows in OLYMPUS Stream™ software to help customers efficiently meet ASTM standards for the manufacturing process. Here are two examples.

1. ASTM E1268

ASTM E1268 is an international standard practice to assess the degree of banding or the orientation of microstructures. Banding and orientation can affect a materials’ mechanical properties, such as the microhardness, and impact the strength of carbon or alloy steels. For this reason, inspectors use this standard to help ensure material quality after heat treatments in the manufacturing process.

For this standard, metallurgists must qualitatively describe the nature of banded or oriented microstructures based on their structural appearance. One customer approached us and asked if there was a way we could modify OLYMPUS Stream software to help them quickly and accurately acquire measured values for the ASTM E1268 standard. We got to work and created a special workflow for their OLYMPUS Stream software. Here’s how it works:

Measure banding and orientation with a pre-set grid

In this custom setup, the operator places a grid with a previously set line distance and size over the image of the sample. Then an automated threshold-based analysis runs to see if the alloy phase, or a part of the phase, is located on the image gridlines. Full or half weighted counts will apply depending on how distinct the phase or part appears on the grid.

The result is then evaluated based on the ASTM E1268 standard. The system will calculate the following features to characterize the banding:

N |_ [1/mm]: Number of feature interceptions with grid lines perpendicular to the deformation direction.
N || [1/mm]: Number of feature interceptions with grid lines parallel to the deformation direction.
Anisotropy index (AI): Ratio between N |_ and N ||.
Degree of orientation (Ω): Degree of orientation of partially oriented linear structure elements on the two-dimensional plane of polish (greater than zero for horizontal orientation; near zero for a non-orientated structure).
Band spacing [μm] (SB): Mean center-to-center spacing of the bands; this feature is only useful for strong banded structures.
Free path spacing [μm] (λ): Mean edge-to-edge spacing of the bands; this feature is only useful for strong banded structures.

Setting up the custom OLYMPUS Stream workflow for ASTM E1268

Here’s a quick overview of how the customer set up this workflow:

First, the operator opens the custom workflow window in a separate tab to easily access both the OLYMPUS Stream standard features and the custom functions.

The workflow area provides options to define the threshold (intensity range for the particle phase) and the measurement grid (line distance and size).

The operator then clicks the Measure button to execute the measurement. Values are displayed in the sheet area, and the grid shows marked line sections based on the phase membership.

When finished, the operator can save the resulting sheet as an Excel workbook in an XLSX or CSV file. They can then convert the measurement overlay to a standard Stream overlay by selecting Copy Overlay.

2. ASTM E562

ASTM E562 is an international standard test method for determining the area of a material phase (also known as the volume fraction) with a systematic manual point count procedure. Metallographic inspectors use this method to count distinguishable constituents or phases within a microstructure. Inspectors can apply this test method to any solid material where adequate 2D sections can be prepared and observed.

In manufacturing, ASTM E562 is commonly used to measure the ferrite content of duplex stainless steel (DSS) welds to ensure the material retained its mechanical properties and corrosion resistance after welding.

We built a custom workflow for a customers’ OLYMPUS Stream image analysis software to streamline this test method. It works like this:

The point grid for systematic manual point counting

In this custom setup, a grid with a previously set number of grid points is placed over the image of the sample. The number of grid points is defined with the option Define Grid. A visual assessment is then carried out to see if the phase, or a part of the phase, is located on the grid point in the image. Full or half points are counted depending on how distinct the phase or part appears on the grid point.

The result of the manual point count is evaluated based on the ASTM E562 standard. The statistical parameters include:

Area fraction: The area fraction is the percentage of the area ratio of the assessed components for the acquired image.
Mean area fraction: The mean area ratio is the area ratio as a percent average on all point counts of all images.
Standard deviation: The standard deviation is a measure for the deviation from the mean. In case of a manual point count, the mean is defined as mean area ratio. The standard deviation shows how intense the found values are scattered around the mean value (mean area fraction in %), in other words, the extent of fluctuation.
Confidence interval (CI): The confidence interval is the so-called confidence range. In other words, a confidence interval of 95 means that there is a 95% probability that the found values contain the true position of the parameter.
Relative accuracy: The relative accuracy shows how precise the measurement is. The relative accuracy increases with the number of counted points per grid.

Now let’s explore how our customer set up this special workflow.

Setting up the custom OLYMPUS Stream workflow for ASTM E562

As we mentioned in the previous example, the operators open the custom solution window in a new tab with the standard OLYMPUS Stream capabilities in another. In the custom tool window, the image area will synchronize with the live image or recently acquired images.

To switch between different images, operators can use the gallery tool window in the standard OLYMPUS Stream tab. The workflow area includes options to define the measurement grid and perform full and half rated counts, as well as options to delete selected single measurement points and the entire actual measurement.

To finalize, the operator finds the manual counting results in the sheet area of the tool window and saves this sheet as an Excel-compatible CSV file. Then they can save the measurement overlay with the Copy Grid button.

Meet global standards with personalized workflows

These examples just scratch the surface. Today there are over 12,000 global ASTM standards, and our custom solution workflows can help metallurgists reduce repetitive tasks and the time spent training personnel.

If you want to personalize your current OLYMPUS Stream workflow for ASTM, ISO, and other international standards, then reach out to us today.