Best Drill Bits for Hardened Steel 

What Are the Best Drill Bits for Drilling Through Hardened Steel?

If you have ever attempted drilling through hardened steel, or any hardened metal, then you know just how tough that can be. Using an ordinary drill bit designed for normal metal materials will not work, and in fact will ruin that bit for other uses.

The perfect drill for taking on hardened steel is a "Cobalt HSS"
drill bit which has been specifically designed for this purpose. We shall go on to show you the best types of those, but for now we would like to briefly explain what hardened steel is, and how it is  made.

Top 4 Drill Bits for Drilling Hardened Steel

Dewalt DW1361 Titanium Drill Bit Set

The DEWALT DW1361 Titanium Pilot Point Drill Bit Set for Steel is one of the best sellers on the market for this type of work.

This set includes sizes from 1/16-inch to 1/2-inch and they come in a tough plastic case, which will help keep them safely stored. Just remember these need to be used in a Jacob's style chuck.

They have a titanium pilot point which ensures a much longer life for each of your bits. As you can these are very highly rated and one of the best sets on the market right now, in my opinion.

Picture of a Dewalt DW1361 Titanium

96% buyer satisfaction based on 13,000+ online buyer reviews

IRWIN Drill Bit Set, Cobalt, Jobber, Fractional, 21-Piece (63221)

If you can afford these cobalt drills then these will last you for a very long time. These are very high quality and will last a long time. Buying cheap drill bits is never a good idea in my honest opinion.

I have done that in the past and the reality is that after a few uses you may as well throw them away as they become blunt and useless for drilling.

I think you are better with one good set that you can reply on to get the job done. The problem is of course you will have to pay to get that type of quality. Buyers rate this Irwin set with an overall 86% buyer satisfaction rating.

I guess therefore it depends on how much use they are going to get and how much you really need or depend on them.

This set gives you 21 high quality cobalt bits and are M42 rated with a 5% cobalt content.

IRWIN Drill Bit Set

94% buyer satisfaction based on 900+ online buyer reviews

Irwin Industrial Tools 316015 Cobalt Drill Bit Set

At number 4 on my list is this set from the higher end Irwin brand. This is a 15 piece set which is popular with many online buyers. Overall those same buyers have given this set of drills an online buyer satisfaction rating of 86%.

Most buyers say that these do a very good job and are made to last. The majority of buyers used these for drilling out broken off bolts. Quite a number of other buyers said they used these on manifolds for removing old exhaust systems.

Most buyers said they did a good job at that, though a small number of people said that these were poor quality, and would not drill out the really hard bolts, that has been rusted in place.

At a price point of around $30-40 for the set we think these are good value for money. We wouldn't want to pay much more for them though.

Irwin Industrial Tools 316015

85% buyer satisfaction based on 200+ online buyer reviews

Hymnorq Metric M35 Cobalt Steel

These are made from M35 cobalt steel, with molybdenum and cobalt added to create a hardened alloy, measuring Rockwell hardness up to 67

They are heat resistant; for much faster cutting and extra longer life span, with up to twelve times when compared with an average HSS drill bit.

The set includes 13pcs of M35 cobalt steel twist drill bits: 1.5mm, 2mm, 2.5mm, 3mm, 3.2mm, 3.5mm, 4mm, 4.5mm, 4.8mm, 5mm, 5.5mm, 6mm, 6.5mm.

These are good for cutting through hard metals such as stainless steel and cast iron, although they can be used for softer materials, too. 

Hymnorq Metric M35 Drill bit set

90% buyer satisfaction based on 1,500+ online buyer reviews

Is It Hard to Drill Hardened Steel?

If you have never done this before, then you are in for a pretty tough piece of drilling. Attempting to do this with any of the standard drill bits that you get will be impossible. f you try to use any of those, then not only will you be wasting your time, but the hardened steel will ruin those bits for use on other types of softer metals.

You need a drill bit that has been designed to cut its way through the hardened steel and a cobalt drill is the correct type.

We have listed below the best cobalt drill bits available on the market today. Just before you have a look at them I think it is important to understand how HSS drill bits are actually graded.

Cobalt Drill Bit Grading of Drill Bits

There are basically 5 different levels of HSS drill bits:

  1. T1
  2. M2
  3. M7
  4. M35 - 5% cobalt
  5. M42 - 8% cobalt

The best choice for drilling through hardened steel is the M42 rated drill bits.

The logic is that to drill through any material the drill bit that you are using has to be made of a material that is harder, than the material you are trying to drill through.

In addition to this, very high temperatures will be created when you perform any kind of drilling task. With the Dewalt DW1361 set, you get 21 high quality drills, at a very affordable price.

Hardened Steel General Information

We have included a video below on how to harden mild steel.

How Is Hardened Steel Made and Produced?

We always find that when we understand how something is made, that it is easier to understand how you can work with it. This includes how to drill it. Hardened steel will take an ordinary steel that is high in carbon content and put it through the processes of quenching and then tempering.

To harden steel, extremely high temperatures are used, and that type of steel must have a lot of carbon in it to begin with.
All hardened steels go through a four step process which we will not bore you with here. It is important to note that the carbon steel is heated to high temperatures which hardens the steel.

It is then dipped into cold water, pretty much in the way you would see a blacksmith working, but that makes it brittle. This is the quenching process. The tempering process then reduces how brittle the steel becomes and the net result is you are left with a pretty tough hardened steel product.

Different Uses of Hardened Steel

Hardened steel is used for objects that are subject to high levels of force or abuse such as cranes, car parts, trucks, hand tools, guns, and knives to name but a few. Compared to ordinary steel, hardened steel is much more durable, more resistant to wear and tear and perfect material for all types of heavy duty applications.

That concludes our reviews, on what we believe to be the best drill bits for hardened steel. You can of course just buy a single drill bit on its own as long as you know the exact size.

Drill bit sets though are always better value for money. As long as you are going to make use of the full set, then these should be considered. This type of drill bit is not something that most home owners will only ever use once or twice. It is always handy to have a small set of these in your tool box though, as you never know when you will need them.

We have used these to drill into garage doors, and some aluminium shelving. Hopefully you found our reviews on the best drill bits for hardened steel helpful and informative. If you are still not sure then check out our article on which drill bit to use.

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