Macroetching, which is the etching of specimens for macrostructural examination at low magnifications, is frequently used in the study of weld structure, definition of weld penetration, dilution of filler metal by base metals, entrapment of flux, porosity, and cracks in weld and heat affected zones.
Macroetching will also provide information on variations in structure, such as grain size, flow lines, columnar structure, dendrites, etc.; and variations in chemical composition as evidenced by segregation, carbide and ferrite banding, coring, inclusions, and depth of carburization or decarburization.
The primary objective of metallographic examinations is to reveal the constituents and structure of metals and their alloys by means of a light optical or scanning electron microscope. Examination of metallographically prepared specimens are conducted using an advanced high magnification (up till 2000X) optical light microscope.
ASTM GRAIN SIZE DETERMINATION (USING COMPARISON CHARTS FOR UNTWINED GRAINS, TWINNED GRAINS & AUSTENITIC GRAINS IN STEEL: MCQUAID-EHN)
Determination of planar grain size, characterization of the two dimensional grain sections as revealed by the sectioning plane, is conducted.
The determination of average grain size is conducted according to standard ASTM112-13, Standard Test Method for Determining Average Grain Size, by Planemetric (or Jeffrie’s) Procedure.
SCANNING ELECTRON MICROSCOPY (SEM) / ENERGY DISPERSIVE X-RAY (EDX) ANALYSIS
A microscopy technique mainly focused on the usage of the Energy Dispersive X-Ray (EDX) detector coupled to the Scanning Electron Microscope (SEM) to examine surfaces of post-corrosion test coupons. it is used to identify and determine the elemental composition and nature of the corrosion deposits.
FERRITE CONTENT BY POINT COUNT METHOD (LAB-BASED)
This is a systematic manual point counting procedure for statistically estimating the volume fraction of an identifiable constituent or phase (e.g. ferrite in duplex stainless steel) from sections through the microstructure by means of a point grid.
ENERGY DISPERSIVE X-RAY (EDX) SPECTROSCOPY
Energy-dispersive X-ray spectroscopy (EDS, EDX, EDXS or XEDS), sometimes called energy dispersive X-ray analysis (EDXA) is an analytical technique used for the elemental analysis or chemical characterization of a sample.
Standard elemental composition of surface deposits and contaminants can be determined by this spectroscopy method.