Laser as a "hammer" -

The new strategy of 3D printing innovates the "iron-making" process

【Editor-in-Chief Circle】

Science and Technology Daily, Beijing, October 10 (Reporter Zhang Jiaxin) In ancient times, people repeatedly hammered pig iron that burned red at high temperatures, and finally turned pig iron into steel. Now, a team led by the University of Cambridge in the United Kingdom has revolutionized technology and developed a new way to print metal in three dimensions (30D) by "programming" structural changes into metal alloys during the printing process, fine-tuning their properties without the need for a "heat forging" process that has been going on for thousands of years. This approach reduces costs and makes more efficient use of resources. The findings were published in the journal Nature Communications on the 3th.

Since the Bronze Age, metal parts have been made by a process of heating and forging. This method uses a hammer to harden the material and then soften it with fire, allowing one to make the metal into the desired shape while giving it flexibility or strength. What makes heating and forging so effective is that it changes the internal structure of the material, allowing it to control its properties.

One of the main drawbacks of current 3D printing technology is the inability to control the internal structure in the same way. This time, the team has developed a new strategy for 3D printing metals that allows for a high degree of control over the internal structure of the material as it is melted by the laser. By controlling how the material solidifies after melting, and the amount of heat generated in the process, researchers can program the properties of the final material.

When a 3D-printed metal part is placed at a relatively low temperature, it triggers a controlled restructuring of the microstructure, a strategy that can fully control the strength and toughness of the metal.

Researchers have found that during the 3D printing process, lasers can be used as miniature "hammers" to harden the metal. However, melting the metal a second time with the same laser relaxes its structure, allowing for a reconfiguration of the structure when the part is placed in the furnace. Their 3D-printed steel has been theoretically designed and experimentally verified, and its performance is comparable to that of steel made from heating and forging.

Steel and iron, in terms of their constituent elements, are not much different. Iron can be made into steel. To put it simply, after high-temperature calcination and other processes, the carbon content of iron is reduced, and steel becomes formed. Steel products have high strength, good toughness, high temperature resistance, corrosion resistance, easy processing... A variety of advantages make it throw off the iron several grades at once. These subtle and complex chemical processes are now replicated in 3D printing. The research team used lasers to change the internal structure of metal materials to control their properties. We will also add chromium, manganese and other elements to the steel, and in the future, 3D printed steel may also continue to be upgraded, showing different alloy steel characteristics.