Impact Testing: The Key to Quality Control of Metal Parts

In the application field of metal materials, whether it is a foundry or a forging plant, the performance of metal materials is directly related to the quality, safety, and service life of the products. Among them, the impact test of metal materials plays an indispensable role as an important means to evaluate the performance of materials under sudden impact loads.

The Importance of Impact Test

In the actual working environment, metal materials are often subjected to sudden impacts, such as violent collisions during mechanical failures and accidental collisions during equipment operation. Impact tests can simulate these actual scenarios and gain an in-depth understanding of the impact resistance and damage mechanism of materials. Through impact tests, factories can ensure that the materials used can withstand potential impacts in the intended application and provide guarantees for the safety of products. At the same time, the data provided by the test helps to predict the performance of materials in actual applications, determine the durability and service life of materials and products, and is crucial for product quality control.

Temperature is a critical factor influencing the impact resistance of metal materials. Generally, metal materials exhibit different impact toughness at various temperatures. At lower temperatures, metals tend to become more brittle, leading to a significant decrease in impact resistance and an increased likelihood of brittle fracture. Conversely, at higher temperatures, metals usually display better ductility and toughness, enhancing their ability to absorb impact energy. Therefore, conducting impact tests across a range of temperatures is essential to comprehensively evaluate the performance of metal materials under different thermal conditions.

Impact Test Examples In Foundries

In foundries, the castings produced are widely used in various machinery and equipment. For example, the cylinder block of an automobile engine, the bed of a machine tool, etc. These castings may be subjected to impact forces from different directions during operation.

Taking the production of automobile engine cylinder blocks as an example, after casting, a certain number of cost test bars need to be drawn from the same batch for impact testing. The Charpy impact test method is usually used. The notched specimen is placed on the testing machine, and the specimen is hit by a pendulum to measure the energy absorbed when it breaks.

Temperature control is vital during these impact tests. Typically, the impact tests on these cost test bars are conducted over a temperature range that reflects the actual operating conditions of the cylinder block, often spanning from sub-zero temperatures (e.g., -40°C) to elevated temperatures (e.g., 200°C). Before testing, the specimens are carefully conditioned to the desired temperature using environmental chambers or liquid baths to ensure consistent and accurate results.

If the energy absorbed by the specimen is lower than the specified standard value at any tested temperature, it means that the material toughness of the batch of castings is insufficient for that specific thermal condition. During the operation of the engine, brittle fracture may occur due to the impact force on the cylinder block, resulting in engine failure or even safety accidents. Therefore, the factory will adjust the casting process according to the results of the impact test, such as adjusting the alloy composition, optimizing the casting temperature and cooling rate, etc., to improve the impact resistance of the casting material across the relevant temperature spectrum.

Impact Test Example In Forging Plant

Forgings produced by forging plants have higher strength and toughness, and are often used to manufacture parts that bear high loads, such as blades of aircraft engines and crankshafts of large ships. During operation, these parts not only have to bear static loads, but also have to deal with various sudden impacts.

Taking aircraft engine blades as an example, during the flight of the aircraft, the blades may be impacted by bird strikes, airflow disturbances, etc. In order to ensure the safety and reliability of the blades, the forging factory will conduct impact tests on the blade materials after forging. Generally, the Izod impact test method is used to impact the vertically placed specimens.

Similar to foundries, forging plants also consider temperature as a crucial variable in impact testing. Aircraft engine blades may encounter extreme temperatures, from the frigid conditions at high altitudes to the intense heat generated by engine operation. Thus, impact tests are performed over a wide temperature range, often from -60°C to 300°C or even higher, depending on the specific application requirements.

Through the test, the toughness, resilience, and fracture resistance of the material under dynamic load at different temperatures can be understood. If the test results are not ideal at any temperature, the factory will analyze the reasons, which may be insufficient deformation during the forging process, inappropriate heating temperature, etc., and then adjust the forging process parameters in a targeted manner to ensure that the blade material has sufficient impact resistance across the entire operating temperature range.

SMEMACH's Impact Test Equipment And Services

Our casting and forging factories have professional pendulum impact test and drop hammer impact test equipment. These equipment can accurately measure the impact resistance of metal materials under dynamic loads. The pendulum impact test equipment applies impact force to the specimen through the swing of the pendulum and measures the energy absorbed by the specimen; the drop hammer impact test equipment impacts the specimen by controlling the height and mass of the drop hammer to simulate impact conditions at different energy levels.

In addition to the basic impact testing capabilities, our equipment is equipped with advanced temperature control systems. These systems allow precise regulation of the specimen temperature during testing, enabling accurate assessments of material performance across a broad temperature spectrum. Whether it's sub-zero conditions or high-temperature environments, our equipment can maintain the desired temperature with minimal fluctuations, ensuring reliable and repeatable test results.

Using impact test equipment, the factory can accurately obtain the impact performance data of the material, providing a strong basis for the optimization of production processes and the control of product quality. At the same time, the factory can also provide relevant technical support and after-sales service to help the factory better carry out impact testing.

Metal material impact testing is of great significance in casting and forging factories. By conducting impact tests on cost test bars across a range of temperatures, the factory can timely understand the impact resistance of the material under different thermal conditions and take corresponding measures to ensure product quality and safety. SMEMACH's impact testing equipment and services provide strong technical support for the factory and help the high-quality development of the metal materials industry.