Metal impact testing machine, metal toughness tester

Resilience is the ability of a material to absorb energy during elastic deformation, plastic deformation, and fracture processes. Materials with good toughness will not suddenly undergo brittle fracture under service conditions, ensuring safety.

The measurement principle of impact absorption energy is that a portion of the energy in the form of pendulum potential energy before impact is absorbed by the specimen during the fracture process after impact. The difference between the starting height of the pendulum and the maximum height it reaches after punching the specimen can be directly converted into the energy consumed by the specimen during the punching process, and the work absorbed by the specimen is called impact energy.

Use a pendulum of a specified height to strike a series of notched specimens of simply supported beams at different temperatures in one go, and measure the impact absorption energy at the time of fracture of each specimen. Changing the test temperature and conducting a series of impact tests to determine the temperature range at which materials transition from human nature to brittleness is called "impact testing". The ductile brittle transition temperature is the temperature at which the Ak value on the Ak-T curve significantly decreases. The middle part where the impact energy of the curve changes significantly is called the transition zone, and the temperature at which the brittle zone and plastic zone each account for 50% is called the ductile brittle transition temperature. When the crystalline or cleavage like brittle zone on the fracture surface reaches 50%, the corresponding temperature is called the fracture morphology transformation temperature.

1. Brittle fracture: Materials will exhibit brittle fracture at low temperatures. Brittle fracture is a rapid fracture process that absorbs very little energy, and there is a lack of significant plastic deformation before and during the fracture process.

2. Brittle ductile transition: The energy absorbed by a material during fracture under impact load within a limited temperature range will undergo significant changes. This phenomenon is called the ductile brittle transition of materials.

3. Cleavage fracture: The phenomenon of transgranular fracture that occurs rapidly along a specific crystal plane when the applied normal stress reaches a certain value is called cleavage; The basic microscopic features of cleavage fracture are steps, rivers, snake like patterns, etc.

4. Full toughness fracture: The percentage of crystalline zone area on the fracture is set at 0%; Fully brittle fracture: The percentage of crystalline zone area on the fracture is set at 100%;

5. Brittle fracture: The percentage of crystalline zone area on the fracture surface needs to be measured using a tool microscope. The fracture surface of the fracture specimen can be observed under the microscope, and the brittle fracture part generally shows a scattered distribution of bright and dark spots. The area of the brittle fracture trapezoid can be calculated through measurement.