High-Speed Steels (HSS)

High-Speed Steels (HSS) are the cutting tool materials used for machining of materials. The HSS will be used for machining of materials. The General use of HSS is 18-4-1.

  • 18% of Tungsten or Molybdenum, used for increasing hot hardness temperature of tool material.
  • 4% of Chromium, used for increasing the strength of resistance to deformation of the cutting tool material.
  • 1% of Vanadium, used for improving the wear resistance of the cutting tool material or for maintaining the keenness of cutting edge.

In addition to these 2.5 to 10 %, cobalt is used to increase the red-hot hardness of tool.

Drill bits made of High Speed Steels

Drill bits made of High-Speed Steels

If 18% tungsten is used in the HSS is called tungsten based HSS and if 18% molybdenum is used in HSS is called molybdenum based HSS. Out of the two the most commonly used HSS is the tungsten-based HSS even though the molybdenum is cheaper than tungsten because the tungsten-based HSS will have higher wear resistance than the molybdenum-based HSS.

HSS is the most commonly used cutting tool material for machining of materials with a cutting velocity of 40 to 50 m/min. HSS cutting tool is preferable to use for machining of large carbon workpieces because the presence of nearly 76% of iron in the HSS cutting tool will attract the carbon atoms from the high carbon workpiece and produce Built Up Edge (BUE) on the HSS tool. Hence for machining of large carbon workpieces in place of HSS the satellite cutting tools are used.

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Vinodh Reddy is a Mechanical Engineer and Editor-in-chief of ME Mechanical. He holds a Bachelor of Engineering (Honours) degree in Mechanical Engineering. He also blogs at Way2Learn for Exams. He interested in the manufacturing field.

All Comments

  • there is no information about cobalt presence in hss
    molybdenum hss has higher strength then T1 Steel and same red hardness but additional cobalt content has high wear resistance at high temperature , more cobalt is better then high tungsten ,,

    manjit Jan 17, 2018 7:14 pm Reply

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