440 steel is not an exciting or new alloy; it has been around for quite some time, strictly because it is a good steel. In fact, it is a very tough and durable stainless steel. Despite the fact that there are newer alloys (such as CPM154CM) that seem to have marked advantages over 440, 440 continues to be produced and used because it has some unique benefits that other steels do not offer in the same configuration.
Among the attributes of 440 steel is its high corrosion resistance and excellent ability to retain a sharp edge when properly heat treated. It also has great strength and toughness, and it can be easily worked by conventional methods.
When it comes to the fabrication of 440, the grade is often supplied in the form of long bars, wires, billets or coils. These raw forms are the most conducive to metalworking. However, the grade is also available in free-machining conditions. This improves machining and reduces the amount of work hardening required, though it does sacrifice some of the strength at elevated temperatures.
440 steel contains 0.5% molybdenum, which helps to increase the hardenability of the alloy. It is also beneficial to the formation of chromium carbides and eta carbides, both of which enhance the strength, corrosion resistance and abrasion resistance of the steel. These characteristics make 440 one of the most popular and versatile knife blade grades available. Many novices, hobbyists and armchair metallurgists have written off this steel due to cost; this is a shame as the fact is that there are other alloys that are even more expensive but lack some of the positive qualities found in 440 steel.