Nondestructive flaw detection
Microstructure refers to the microstructure observed under optical microscope or electron microscope on the ground surface of metal sample or its replica or film made by appropriate method after treatment by appropriate method (such as erosion). The microstructure of iron and steel is a polymer composed of basic components in the steel and cast iron seen under the metallographic microscope or electron microscope. When observed with metallographic microscope, the surface of the sample should be polished and slightly eroded with appropriate aggressive agent. More complicated sample preparation is needed when observing with electron microscope. The microstructure of steel or cast iron with different carbon content and alloy composition is different. The same composition of steel or cast iron has different microstructure after different metal heat treatment. Different microstructure has different properties, so steel can get different properties through heat treatment. Microstructure analysis of steel is an important means to study steel and evaluate the quality of steel products. The microstructure of steel includes: ferrite, cementite, pearlite, Wei type structure, bainite (including upper bainite, lower bainite, and granular bainite), austenite, martensite, tempered martensite, tempered troostite, tempered listite, etc.