Best Drill Bits For Hardened Steel

There are many other things to consider when choosing the right drill bit for hardened steel. This post will cover what you need to know about drilling hardened steel and provide you with some suggestions on the best drill bits that will work well for your needs.

The best drill bit for hardened steel

Short on time?

If you are short on time, the best drill bits for hardened steel are carbide-tipped bits. They are the most suitable drill bits for hardened steel due to their robust and heat-resistant properties. However, there are other options such as titanium and cobalt. 

If you've worked with hardened steel before, you'll know that a regular drill bit won't cut through. Your best bet is to use the carbide bits because they are the hardest drill bits available.

Carbide drill bits are used for drilling broken bolts, safes, studs, bearing races, taps, and knives made from hardened steel. They are designed to allow the quick dissipation of heat and prevent chipping. 

What Kind of Drill Bit Will Go Through Hardened Steel?

When drilling through hardened steel, you must ensure that your drill bit is made from tougher materials. Carbide bits are the strongest drill bits material and can cut through hardened steel. But if they are not available, titanium and cobalt drill bits can also be used. However, drilling with either of these bits will take longer than drilling with a carbide drill bit.

  • Carbide

  • Carbide drill bits are the toughest drill bits available and best for drilling hardened steel. Carbide is a  compound made from tungsten and carbon. Carbide drill bits are typically composed of steel that has a carbide tip. 

    However, it would be best to exercise caution when using carbide-tipped drills since they can be brittle despite being the hardest. Because of their great strength, they are extensively employed in industrial applications. They can cut through concrete, masonry, tile, and hardened steel. 

  • Cobalt

  • Cobalt drill bits are not made of pure cobalt. Instead, they are made of steel combined with a small proportion of cobalt, often between 5 and 7 percent, and the remaining part steel. 



  • Titanium Coated

    Titanium drill bits are high-speed steel bits with a titanium nitride covering. Titanium-coated drill bits provide many advantages over ordinary steel bits, including the ability to endure greater temperatures, increased wear resistance, and higher durability.

    Titanium nitride (TiN) is a very strong ceramic substance that protects the steel bit and allows it to last longer, especially when drilling hardened steel.

    Is A Cobalt or Titanium Drill Bit Better?

    Titanium drill bits are high-speed steel bits with a titanium nitride (TiN) coating, whereas cobalt drill bits do not have a coating; the entire bit is constructed of alloy steel that contains 5 to 8% cobalt.

    Therefore, cobalt drill bits have a longer life and are more heat resistant than titanium drill bits. Which means cobalt drill bits are typically better since they are much more durable than titanium-coated bits and can drill holes through the hardest metals.

    RUKO MTwist TiN v Cobalt Drills

    When comparing the carbide, both cobalt and titanium drill bits are better than regular steel drill bits due to their added components, as well as their resistance to heat and wear. However, in terms of hardness and longevity, the carbide drill bit is better than both of them.

    Are cobalt drill bits good for hardened steel? 

    Cobalt has a high melting point of 1495°C, making it ideal for high heat drilling applications like hardened steel. The most common are M35, a 5% alloy, and M42, a 7% alloy.

    Which Is Harder Cobalt or Carbide?

    Carbide drill bits are typically harder than cobalt drill bits, although both are suitable for drilling stainless steel and other hard metals. However, Carbide drill bits retain their sharpness for a longer period than cobalt drill bits. They can also be utilized at a faster cutting rate and withstand higher temperatures than cobalt drill bits.

    How To Drill Hardened Steel

    The drill speed is critical for drilling hardened steel. Drilling at high speeds causes high temperatures, which will damage your drill bit. Therefore, drilling hardened steel should be done at a low RPM and feed rate. Feed rates are typically at least 50% lower than for lesser hardness steel. Speeds generally are 30% of that of a non-hardened material.

  • Use Eye Protection
  • For better protection, use safety glasses that wrap around the sides of your face. Eye protection is required to ensure that a tiny metal fragment does not cause significant eye injury.

  • Make a Dimple
  • Measure and mark the hole, then use a center punch and hammer to make a slight indentation. Drill bits tend to wander when they first start drilling. Therefore the dimple helps the drill bit become more steady. The dimple also serves as a reference for where to drill your hole.

  • Secure with a clamp
  • Make sure the piece of metal is in a flat and secure area. Holding the metal with one hand while running the drill with the other is not a good idea. It is better to secure the metal with a clamp.

  • Use Lubricant
    RUKO Lubricant
  • Lubricant should be applied to both the drill bit and the drilling surface. To reduce the temperature, repeat this step between drillings.




  • Drill at a Slow Speed 
  • Drill through-hardened steel metal at the recommended speed using a drill bit, preferably carbide bits. Larger drill bits require even slower speeds. 

    High Tensile Steel

    Surface Feet per Minute (SFM)

    Rockwell C 40 to 45 

    20 - 30

    Rockwell C 40 to 45 

    30 - 40 

    Rockwell C 45 to 50 

    25 - 35 

    Rockwell C 50 to 55 

    15 - 25 

    Rockwell C 56 and higher

    7 - 15

    RPM =SFM x 3.82Drill Diameter

    Rockwell hardness testing is a standard method for determining the  hardness of metals and polymers. Rockwell hardness is measured with a device known as a Rockwell hardness tester. The tougher the steel is, the higher the number on the RC scale. The higher the RC number, the slower the drill speed should be. 

    In computing for the RPM, for example 1"-diameter tool must run at 30 sfm. Based on the equation above, at 30  sfm: (30 × 3.82) ÷ 1 = 114.6, this means you have to use 115 RPM to drill a 1 inch Rockwell C 40 to 45 steel. 

     Where is hardened Steel used?

    Hardened steel types include ATS34, CPM440V, Z60CDV14,  Sandvic, and 12C27. Carbon steel must go through a succession of heat treatments, quenching, and reheating to become hardened steel. 

    Hardened steel is used in energy,  transportation, general mechanical engineering components, and many other applications. Axles, arbors, driving pinions, camshafts, and Cardan joints are examples of hardened steel components.

    If you are in the process of drilling hardened steel, maybe for one of the reasons mentioned above, or potentially something completely different, why not take a look at the drill bits we have available for metal. Our range is designed for high end performance and is suitable for those drilling hardened and normal stainless steel.

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