Easy mastery of metallographic cutting direction skills

The cutting of metallographic specimens is an important step in the preparation process of metallographic specimens. The methods for cutting patterns include hand saws, sawing machines, grinding wheel cutting machines, and wire cutting machines, among others. Choose an appropriate method for cutting based on the shape and material of the parts. Grinding wheel cutting machines are mainly widely used for cutting metallographic specimens due to their strong adaptability and relatively high cutting accuracy. Resin grinding wheels can cut soft metal parts such as copper, aluminum, and alloys, as well as hard metal parts such as quenched carbon steel and high-speed steel. Diamond cutting blades can cut superhard materials such as hard alloys, ceramics, etc.

Requirements for cutting direction: For different material testing requirements, there are requirements for the cutting direction. Taking metal materials as an example:Vertical sampling refers to cutting a sample along the direction of forging and rolling, which can be used to detect the degree of deformation of non-metallic inclusions, grain distortion, plastic deformation, various structural morphologies after deformation, and the overall situation of heat treatment, etc.Horizontal sampling refers to cutting a sample perpendicular to the direction of forging and rolling, which can be used to detect the microstructure, grain size level, carbide network, depth of surface defects, depth of oxide layer, depth of decarburization layer, depth of corrosion layer, surface chemical heat treatment, and coating size from surface to center.The requirement for cutting direction can be achieved through the feed direction of the cutting machine and the sample clamping direction.When cutting, try to maintain the original characteristics of the material as much as possible: the requirements for metallographic sampling should not only be based on the convenience of observation, but also on the purpose of observation.Taking the observation of coating as an example, if cutting from the substrate to the coating, the cutting process will generate a certain amount of tearing stress on the joint between the coating and the substrate, causing deformation of the joint and affecting the observation.Taking soft or brittle materials as an example, if the tearing stress caused by the cutting process is relatively strong, it may cause deformation of the matrix morphology, affecting observation.It is difficult to avoid tissue deformation caused by the cutting process, and deformation can be minimized by controlling the cutting speed and direction, as well as effective cooling.