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Scientists MIT have discovered why razor blades become blunt repeated use. They did research why razor blades lose their sharpness. Razor blades are 50 times harder than the hairs they cut. Even though human hair is 50 times softer than the metal a razor blade, the hair damages the edge the blade. Razor blades are made stainless steel. They are usually coated tougher materials like hardened carbon. The MIT scientists said that each time a blade cuts a hair, the hair causes tiny amounts damage. A blade usually cuts thousands of hairs one shaving session. This means the life a razor blade is limited and will need to be replaced regularly.

The researchers used powerful microscopes to find out how hair damages a razor blade. They got a close- view of what happens a shave when the blade cuts a hair. The blade gets damaged a variety of ways. One way is that a single hair creates a tiny chip the edge a blade. This chip becomes bigger as it cuts more hair. After more shaving, the blade loses its ability to cut cleanly and becomes blunt. A researcher said: "We are metallurgists and want to...make better metals. this case, it was intriguing that if you cut something very soft, human hair, something very hard, steel, the hard material would fail." He said his team is "aiming to solve an important engineering problem".

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