The "seconds" of the barrel's service life do not refer to the installation time, but to the cumulative effective firing time that can withstand the high temperature and high pressure gas pressure and friction generated during the firing of the shell. Taking the 120mm smoothbore gun of the German "Leopard 2" main battle tank as an example, the service life of the barrel is about 1000 rounds of ammunition. When firing one shell, the time for the shell to pass through the barrel is about 5 milliseconds, and the cumulative service life of the barrel for 1000 rounds of ammunition is about 5 seconds. Gun barrel steel is known as the "king of steel" due to its strong hardness. So, why is the lifespan of the gun barrel only a few seconds? Firstly, there is instantaneous high temperature. When a shell is fired, the barrel temperature can reach 2500 to 3500 degrees Celsius, far exceeding the melting point of steel at 1500 degrees Celsius. Although the interior is coated with a heat-resistant layer, repeated temperature fluctuations can cause metal fatigue and even coating peeling. Next is high-pressure shock. When a shell is fired, the barrel pressure can reach 300 to 600 megapascals, and the enormous pressure can cause the barrel to deform and crack, resulting in rifling wear. Finally, there is chemical corrosion. When gunpowder burns, gases such as hydrogen sulfide produced can cause damage to the inner wall of the barrel. So, how to extend the lifespan of a gun barrel? The first move is to innovate materials. During the casting process, the factory adopts a composite formula of high-strength alloy steel and rare earth elements to enhance the metal's high temperature resistance and fatigue resistance. The second trick is to upgrade the technology. Through advanced manufacturing processes, impurities such as pores inside the metal are eliminated, and plasma spraying technology is used to form a nanoscale ceramic coating on the inner wall of the gun barrel, which not only enhances wear resistance but also isolates chemical corrosion. In addition, in order to improve the service life of the gun barrel, maintenance work must be done after the gun is installed. Built in micro sensors in the barrel to monitor chamber pressure and temperature in real-time, avoiding excessive use; Equipped with endoscope and laser ranging equipment, it can detect the depth of rifling and the corrosion of the inner wall, accurately determine maintenance nodes. Data shows that the United States widely uses laser detection systems to perform three-dimensional scanning of the interior of gun barrels, which can identify sub millimeter chromium layer detachment and rifling wear, shifting maintenance decisions from "experience based" to "data based". In the future, with the development of composite materials, magnetron plasma anti ablation technology, and intelligent diagnostic technology, gun barrels will evolve towards lightweight and intelligent directions, further improving durability and sustained combat capabilities. (New Society)