High Speed Steel History
High speed steel grades have been developed over the years primarily for high speed cutting applications, but also for use in the production of tools and dies. The properties of each grade vary, but common properties include high wear resistance and excellent toughness. High speed steel grades also have high heat resistance up to 500°C, which makes them perfect for high speed use, hence the name.
Through heat treatment, these steels can achieve high Rockwell hardness, for example, M2 HSS is typically hardened to 64 HRC, while M42 can be hardened to as high as 70 HRC, although it is typically hardened to 66-68 HRC.
The chemical composition of HSS grades combines some or all of the alloying elements of carbon, chromium, molybdenum, vanadium, tungsten and cobalt. Grades combining carbon, vanadium and tungsten can provide the highest wear resistance. Cobalt grades provide improved thermal hardness and washability, but reduced toughness.
In 1868, Robert Meashet invented a self-hardening/air-hardening steel called wheat steel or R-ear bean special steel. This was the first known special steel that gained a degree of hardness when forged and cooled. It was widely used for engineering tools and was patented at the time, its chemical composition remaining secret. We now know that the 8% tungsten content is the key to the steel’s properties. In 1870, Samuel Osborn & Company of Selfrid, Selfrid, England, purchased the mass production of steel.
In the nineteenth century in the United States, Frederick Taylor and British, Maunsel White, who worked for Bethlehem Steel in Pennsylvania, did many tests and experiments on wheat steel to learn more about its characteristics. During these experiments, they found that adding 3.8 percent chromium to 8 percent tungsten steel allowed it to be quenched and tempered at high temperatures (near the steel’s melting point)). In the service used, it could work at a faster rate than Meashet steel. The name given is High Speed Steel.
T1 was one of the first mass-produced high-speed steels. It was developed and manufactured in 1910 and patented by the Crucible Steel Company in New Jersey, USA. In 1937 W Breelor, USA, invented the tungsten-molybdenum high-speed steel M2.
In the following years, many new grades of HSS were developed. In the UK, numerous specialised steel producers (mainly in Sheffield) made numerous HSS, as well as tool steel grades. It is common for a universal presence to exist for each manufacturer to offer each grade a unique company steel brand. For example, Samuel Osborn & Company is a good example of a company that prides itself on using the Mushet name in its HSS grades;
Samuel Osborn brand AISI BS4659*
Dual Particle ND T1 BT1
triple wheat floor GZ T4 BT4
mushet MKK M2 BM2
Meashet Special VG M15 BM15
* (introduced in 1971)
General HSS Specifications
The many brand names given to tools and HSS are confusing to buyers. In 1971, the British Standards Institution utilized a new standard for all major types of tool and HSS steels used in the UK, called BS4659. overtime to accelerate the production of a reduced range of HSS. The most popular grades are now M2, M35 and M42, available in round bar, flat bar and plate.
With its tungsten-molybdenum combination M2 HSS provides high wear resistance after hardening. With better toughness and good cutting power, it has now been replaced as the most popular grade of HSS. Today T1 is rarely produced or stocked in the UK.
The addition of cobalt to M35 gives it better heat resistance properties than M2.
Has high hardness (up to 70Hrc) and excellent hot hardness tooling made from M42 tools, providing excellent serviceability.
Applications
HSS specifications are commonly used for tool bits, cutting tools, taps, drills, cutters and strip blades. Utilizing their high hardness and high wear resistance HSS are commonly used in tooling applications such as punches and components of dies.
