Molybdenum steel is a high-strength alloy used across a variety of industries. Steel alloys made with molybdenum are not only stronger and harder, they also are highly resistant to heat and corrosion. Electronics, heavy machine parts, tools and aircraft parts are often made with steel alloys that contain molybdenum.
The unique properties of molybdenum make it useful in steel alloys. Molybdenum is highly heat resistant and can withstand extremely high temperatures, with an exceptionally high melting temperature, and it also is an excellent thermal conductor. Alloys of molybdenum steel retain their strength when heated and are less likely to expand, soften or become deformed. Tools and parts exposed to extreme friction are often made from these alloys.
Steel made with molybdenum have other advantages as well. Molybdenum steel is highly resistant to corrosion and is used in stainless steel alloys for greater protection. The alloy is also easy to weld, making it especially versatile. It is only slightly more dense than iron and much lighter than tungsten, meaning that molybdenum can provide strength without dramatic increases in weight.
There is no single molybdenum steel, and a wide variety of alloys containing molybdenum are produced for specific applications. Most molybdenum alloys contain anywhere from 0.25 percent molybdenum to 8 percent molybdenum. Many nickel- and titanium-based steel alloys include molybdenum as well.
Before the 20th century, tungsten was most often used to make steel alloys. In the late 19th century, researchers began to experiment with the much lighter element molybdenum and had promising results. A French company named Schneider & Co. became the world’s first molybdenum steel manufacturers when it used the alloy to produce armor plating in 1891.
Throughout the first half of the 20th century, molybdenum began to replace tungsten. During World War I, the demand for tungsten drove up prices, making alternative alloys more attractive. Molybdenum not only was cheaper, the lower weight and higher heat resistance also made the metal more versatile, with manufacturers constantly finding new applications.
Modern industries continue to take advantage of the properties of this alloy. Molybdenum steel is used to make huge structural girders for the construction industry and tiny filaments for electronic devices. Parts for furnaces and turbines, automotive parts, aircraft parts and heavy machine parts such as bearings and dies are all made from these alloys. Stainless steel containing molybdenum is used throughout the pharmaceutical, healthcare, food manufacturing, restaurant and catering industries, as well as anywhere else that hygiene is an issue and sterile surfaces are required.