Tool steels are top quality , carbon and alloy steels that are commonly used to make cutters, reamers, bits etc used for machining metals, plastics, and wood. they’re usually melted in furnaces and processed to supply them properties required for shaping other metals into useful components.
Steels used for creating tools, punches, and dies are perhaps the toughest , the strongest, and toughest steels utilized in industry. it’s obvious that tools used for working steels and other metals must be stronger and harder than the steels or material they cut or form.
The metallurgical characteristics of varied compositions of tool steels are extremely complex. There are many different makes and kinds of tool steels available and every may have a selected composition and end use.
In the us , the Society of Automotive Engineers, in cooperation with the American Iron and Steel Institute, has established a arrangement which relates to the utilization of the fabric and its composition or sort of heat treatment.
In general, tool steels are basically medium- to high-carbon steels with specific elements included in several amounts to supply special characteristics. The carbon within the alloy steel is provided to assist harden the steel to greater hardness for cutting and wear resistance. Other elements are added to supply greater toughness or strength.
In some cases elements are added to retain the dimensions and shape of the tool during its heat treat hardening operation or to form the hardening operation safer and to supply red hardness in order that the tool retains its hardness and strength when it becomes extremely hot. Various alloying elements additionally to carbon are chromium (Cr), cobalt (Co), manganese (Mn), molybdenum (Mo), nickel (Ni), tungsten (W), and vanadium (V).
The addition of elements produces different effects on the resultant composition as follows:
*Chromium produces deeper hardness penetration in heat treatment and contributes wear resistance and toughness.
*Cobalt is employed in high-speed steels and increases the red hardness in order that they will be used at higher operating temperatures.
*Manganese in small amounts is employed to assist in making steel sound and further additions help steel to harden deeper and more quickly in heat treatment. It also helps to lower the quenching temperature necessary to harden steels. Larger amounts of manganese within the 1.20-1.60% range allow steels to be oil quenched instead of water quenched.
*Molybdenum increases the hardness penetration in heat treatment and reduces quenching temperatures. It also helps increase red hardness and wear resistance.
*Nickel adds toughness and wear resistance to steel and is employed in conjunction with hardening elements.
*Tungsten added to the steel increases its wear resistance and provides red hardness characteristics. Approximately 1.5% increases wear resistance and about 4% together with high carbon will greatly increase wear resistance. Tungsten in large quantities with chromium provides for red hardness.
*Vanadium in small quantities increases the toughening effect and reduces grain size. Vanadium in amounts over 1% provides extreme wear resistance especially to high-speed steels. Smaller amounts of vanadium in conjunction with chromium, and tungsten, aid in increasing red hardness properties.
The tool or die steels are designed for special purposes that are dependent upon composition. Certain tool steels are made for producing die blocks; some are made for producing molds, others are made for decent working, and still others for high-speed cutting applications.
The other way for classifying tool steels is consistent with the sort of quench required to harden the steel. the foremost severe quench after heating is that the water quench (water-hardening steels). A less severe quench is that the oil quench obtained by cooling the alloy steel in oil baths (oil-hardening steels). the smallest amount drastic quench is cooling in air (air-hardening steels).
