Grain Size Analysis
Grain size analysis of metal and alloy samples such as aluminum or steel is a very important step in the whole quality control process of metallographic laboratory. The standard grain size is divided into 12 grades, 1-4 grade is coarse grain, 5-8 grade is fine grain, and 9-12 grade is ultra-fine grain size. It is a well-known fact that smaller grain size usually improves the mechanical properties of the sample, so it is very important to control the alloy composition and process to achieve the desired grain size. In addition, grain size analysis is also used to investigate the causes of possible material failures. According to ASTM E112-13 (Standard Test Methods for Determining Average Grain Size), T,C&A Lab can perform grain size analysis on a wide range of metallic materials and nonmetallic materials whose structures having appearances similar to those of the metallic structures. Welcome to contact our experts for consultation.
The grain size test methods T,C&A Lab provides include:
The comparison method does not need to calculate any grains, intercepts, or intersections. There is generally a certain deviation (±0.5 grain size units) when evaluating the grain size by the comparison method. The repeatability and reproducibility of the evaluation value is usually ±1 grain size number.
The planimetric method is to calculate the number of grains in a known area, and use the number of grains per unit area to determine the grain size level. The measurement result of the planimetric method is unbiased, and the accuracy of ±0.25 grain size units can be achieved through reasonable counting. The repeatability and reproducibility of the evaluation value are less than ±0.5 grain size units. The key to the grain size of the planimetric method is the count of grains that are clearly divided by the grain interface.
The intercept method is to calculate the number of intercepts at the intersection of a test line segment (or network) of known length with the grain interface, and use the intercept per unit length to determine the grain size level. The accuracy of the intercept method is a function of the calculated intercept or intersection. The accuracy of the effective statistical results can reach ±0.25 grain size units. The measurement result of the intercept method is unbiased, and the repeatability and reproducibility are less than ±0.5 grain size units.
After obtaining the specific microscopic photos, the average grain diameter can be calculated according to the following process.
Determine picture magnification
First measure the size of the microphotograph, choose one of length or width, and then measure the actual length or width of the sample.
Magnification=picture distance/actual distance
Find out the number of grains per unit
After calculating the magnification, the grain size level can be determined. First, calculate the number of grains in the sample.
The number of grains = the number of complete grains + 0.5 times the partial grains. The grain boundaries of the complete grains are all observable.
Then calculate the actual area, actual area = picture length/magnification rate x width/magnification rate.
According to the calculation formula in ASTM standard: N=2(n-1). Where N refers to the number of grains per square inch under 100 times magnification, and n refers to the grain level. The N can be obtained after unit conversion. Finally, the grain grade number n can be calculated.
Calculate the average grain diameter
Average grain diameter = actual length of the sample / number of grains in the intercepted part
Actual length = cut length / magnification
Instruments and data
T,C&A Lab's services include, but are not limited to
Note: this service is for Research Use Only and Not intended for clinical use.
- Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES)
- X-Ray Fluorescence (XRF) Testing
- X-Ray Photoelectron Spectroscopy (XPS) Testing
- Infrared Spectroscopy Testing
- Ultraviolet Spectrum (UV) Testing
- Mass Spectrometry Testing
- Micro-Raman Spectroscopy Testing
- Nuclear Magnetic Resonance Spectroscopy Testing
- Elemental Analysis
- Structural Characterization
- Morphology & Size Analysis
- Corrosion Inhibitor Testing
- Crevice Corrosion Testing
- Electrochemical Corrosion Testing
- Galvanic Corrosion Testing
- High Pressure High Temperature (HPHT) Corrosion Testing
- Hydrogen Embrittlement Testing
- Intergranular Corrosion (IGC) Testing
- Pitting Corrosion Testing
- Salt Spray Testing
- Sour Service Corrosion Testing
- Stress Corrosion Cracking (SCC) Testing
- Sulfide Stress Cracking (SSC) Testing
- Thermal Analysis
- Mechanical Testing
- Non-Destructive Testing
- Performance Testing
- Pharmaceutical Testing
- Chemical Analysis
- Case Depth Testing and Analysis
- Grain Size Analysis
- Particle Size Distribution Analysis and Testing
- Coating Thickness Testing
- Inclusion Rating
- Ferrite Testing
- Porosity Testing
- Grain Flow Testing and Analysis
- Weld Testing
- X-Ray Diffraction (XRD) Analysis
- Scanning Electron Microscopy (SEM) Laboratory
- Harmful Substances Testing
- Reverse Engineering & Deformulation
- Karl Fischer (KF) Moisture Testing
- Industrial Problem Diagnosis
- Ingredient Analysis