Which Are the Hardest Metals to Cut? Here's the Ranking

Certainly, there is a list of the hardest metals to cut that you need to know when working with band or circular saws. Because if the power tool you use can make a difference, the same goes for the blade you use. It must be aligned with the challenge you face.

There are hard metals to drill and suitable drill bits for these challenges. The same can be said for cutting activities. Here is the ranking of materials you need to handle with due care – and with special blades – when you decide to perform precise cuts.

Always considering that there is a list of the hardest metals on earth and that we must make a difference between materials with high hardness and those difficult to machine: it's not the same thing and those who work in the field of technical activities must be aware of this.

Hard Metals, Here Is the List of the Most Resistant

Let's start with the list of hard metals according to well-known evaluation scales such as Mohs, HRC, and HV. Based on these parameters, which indicate empirical criteria for assessing hardness, we can say that tungsten carbide in its worked form and transformed into Widia or hard metal is certainly the ideal candidate to dominate the ranking of the most difficult metals to machine.

According to the Vickers scale (HV), it can range from 1,600 HV to over 2,400 HV, depending on the cobalt content and grain size distribution of the grains. While the Mohs scale indicates a value of about 9, a characteristic that positions Widia below diamond and cubic boron nitride.

Pure chromium is also very hard, harder than most hardened steels. It has a value of 8.5 on the Mohs scale and, in addition to hardness, offers high wear and corrosion resistance. Shortly after we find the family of hardened carbon or alloy steels that have undergone a heat hardening treatment. Want to evaluate what are the benefits of this step?

On the Vickers scale, a hardened steel reaches approximately 450 - 900 HV, depending on the alloy and degree of hardening. A mild steel reaches 150 - 200 HV, so hardening can triple or quadruple hardness. But strength decreases and these materials become very impact sensitive. This is why machining these materials is particularly complex.

Materials Difficult to Machine Due to Low Machinability

It must be considered that high hardness is not a direct synonym for difficulty in machining. Turning, milling, drilling, and sawing are activities that can change based on the type of material that can have very high values on HRC/HV scales and therefore resist material removal. But there are others that, even if not extremely hard, tend to overheat, harden during cutting (work hardening).

For example, nickel-based superalloys like Inconel, Hastelloy, and Monel resist heat, are abrasive, and consume many tools. Tungsten is also difficult to cut since it is very hard but also brittle. In this list we also have titanium and related alloys (Ti-6Al-4V) that have low thermal conductivity. So they accumulate heat on the cutting edge of the power tool.

Also worth mentioning are cobalt alloys which are highly wear-resistant solutions, a condition that causes problems for standard tools. This is why we recommend considering solutions such as Krino circular saws that allow you to achieve excellent results even on the most complex and difficult materials to cut.