The similarities and differences between the test blocks of the flaw detectors V1 (IIW) and V2 (IIW2) and the basic requirements for the application of standard test blocks: The material of the standard test block should be uniform, with little internal impurities, and no defects that affect the use. It is easy to process, not easy to be deformed and embroidered, and has good acoustic properties. The parallelism, perpendicularity, roughness and dimensional accuracy of the test block should be strictly inspected and meet certain requirements. The standard test block should be made of open-hearth killed steel or electric furnace mild steel, such as No. 20 carbon steel. The flat-bottomed hole on the test block should be inspected for its diameter, surface roughness and flatness at the bottom of the hole. The following inspection methods are commonly used: first clean the hole with a non-corrosive solvent and dry it, then use a syringe to inject the silicone rubber into the hole, draw out the syringe, insert a pin, take out the rubber model with the pin after the rubber is solidified, and check on the optical projector The roughness and flatness of the hole bottom. Commonly used standard test block: IIW test block (V 1 test block): IIW is the abbreviation of International Welding Society

How to optimize the resolution of the microscope As one of the main equipment of inspection equipment, the resolution is an important indicator to judge the performance of the microscope. Resolution refers to the smallest distance between two small dots or two lines that can be clearly distinguished. The human eye itself is a microscope. Under standard lighting conditions, the resolution of the human eye at the photopic distance (the internationally recognized 25cm) is approximately equal to 1/10mm. For observing two straight lines, since the straight line can stimulate a series of nerve cells, the resolution of the eye can be improved. The resolution of the human eye is only 1/10mm, so the human eye cannot distinguish the distance between an object smaller than 1/10mm or two tiny objects closer than 1/10mm. So there has been a simple macroscopic magnifying glass to an optical microscope for microscopic observation, and then an electron microscope. The definition of microscope resolution refers to the minimum distance between two small points that can be clearly distinguished on a specimen. The calculation formula is: D

Brinell hardness tester's test standards, working principle and application scope 1. Brinell hardness test execution standard: The new standard of metal Brinell hardness test method adopts the international standard ISO 6506-1:2005. The new standard is re-drafted in accordance with ISO 6506-1:2005, and according to the actual situation of our country, it has been modified and supplemented when adopting international standards. According to the international standard structure, ISO 6506 is composed of 3 parts: ISO 6506-1:2005 Brinell hardness test method for metallic materials ISO 6506-2:2005 Brinell hardness test hardness tester inspection and calibration for metallic materials ISO 6506-3:2005 Brinell hardness test standard hardness block calibration of metallic materials ISO 6506-4: 2005 Brinell hardness test hardness value table of metallic materials China’s Brinell hardness test method standard compilation is relative to international standards

The contrast between bright and dark field metallurgical microscopes and their applications in metallographic analysis 1. Bright field and dark field imaging principles The principle of dark field imaging is the same, but the imaging effect is opposite to that of bright field. 2. Comparison of the characteristics of bright field and dark field ⑴ Bright field--------the beam of light illuminates the surface of the sample vertically ⑵ Dark field--------the light obliquely illuminates the surface of the sample Optical stroke: There is a significant difference between dark field lighting and bright field lighting in terms of optical path arrangement and lighting effect. To illustrate the effect of dark field lighting, we must first study the optical arrangement of the dark field (see the figure below). The parallel light from the light source is blocked by the circular shading plate, and the central part of the light is blocked. The light passing through the circular shading plate enters the vertical illuminator as a hollow cylindrical beam. The vertical illuminator for dark-field illumination is a circular reflector, which reflects the cylindrical beam upwards and casts it on the metal arc reflecting surface of the reflecting condenser along the objective lens shell.