Tungsten Carbide drill bits are considered the strongest and most durable option on the market, offering extreme hardness, high heat resistance, and long-lasting sharpness. For specialized applications in 2026, the Diablo Rebar Demon and Bosch SpeedXtreme are top choices for concrete and rebar.
For ultimate strength and heat resistance, carbide and cobalt are the strongest drill bits available. The ideal choice depends on your material, with carbide dominating for ultra-hard surfaces and cobalt taking the lead for heavy-duty metal fabrication and everyday abuse.
Cobalt is significantly stronger, harder, and more heat-resistant than titanium drill bits.
Carbide (specifically tungsten carbide) is the hardest and most durable material for drill bits, rating around 82 HRC (Rockwell scale). Because they hold a sharp edge much longer than other materials, they are the top choice for drilling hardened steel, masonry, and concrete. However, they can be brittle and expensive.
To drill hardened steel, you need drill bits made of solid carbide or cobalt (M35 or M42). Carbide is harder than the steel but brittle, while cobalt is a highly heat-resistant steel alloy. Standard high-speed steel (HSS) or black oxide bits will burn out or shatter instantly.
Applications: Due to the above, carbide is ideal for cutting tough materials like hardened steels, stainless steels, and abrasive materials.
For drilling through hardened steel, you need drill bits made of Cobalt (specifically M35 or M42 alloys) or Solid Carbide. These materials retain their hardness at the extreme temperatures generated when cutting tough metals.
Durability: Diamond bits are highly durable compared to carbide bits. These bits can easily drill holes into thick concrete slabs, glass, and tiles. Because of their toughness, they are preferred in the long run. Outstanding Hardness: Diamonds are widely recognized as the hardest natural substance.
If you drill holes through both steel and stainless steel with standard drill bits, it is recommended that you use cutting oil or an appropriate liquid lubricant because the two metals react differently to heat.
Heat Resistance: Both materials exhibit good heat resistance, but tungsten carbide maintains a higher hardness at elevated temperatures compared to HSS, making it more suitable for high-temperature applications.
The metal is highly reactive with oxygen, and when the two elements mix, becomes very fragile and brittle. This makes it brittle and more susceptible to cracking. Oxygen is titanium's biggest enemy.
Cobalt drill bits are extremely durable, particularly when drilling through tough, abrasive materials. They can withstand more stress and last longer than both black oxide and titanium bits in heavy-duty applications. Pros: Best for heavy-duty and tough drilling, great for hard metals.
The Long-Term Cost Benefits of Choosing the Right Bits
Although titanium-coated drill bits are typically more expensive upfront than their standard steel or cobalt counterparts, they're an investment that pays off over time. Their resistance to wear means fewer replacements are needed, saving time and money.
The "best" drill bit depends on what you are cutting and your usage frequency, but Milwaukee, DeWalt, and Irwin are the top consumer brands. For heavy-duty industrial or professional metalwork, USA-made brands like Norseman, Viking, and Champion are widely considered the gold standard.
The best drill bits for thick steel are Cobalt (M35 or M42) drill bits. They are made from a high-speed steel base blended with 5% to 8% cobalt, making them highly heat-resistant and allowing them to chew through thick, hardened, or high-tensile steel without dulling.
Although a cobalt bit can handle much harder material, a titanium drill bit offers good heat resistance and impressive durability. They are well-suited to most general-purpose drilling tasks but might not be the best option for industrial applications.
Yes, WD-40 helps by cooling the bit and clearing metal shavings, but it is primarily a penetrant and not a dedicated cutting lubricant. While standard WD-40 prevents mild steel drilling friction, true cutting fluid or motor oil is much better at withstanding high heat and pressure.
People oppose oil drilling primarily due to the severe environmental and health hazards associated with extraction, refining, and burning. Opponents argue that fossil fuels drive the climate crisis, threaten marine and land ecosystems, and delay the transition to renewable energy sources.
Here is the right way to drill stainless steel:
You need to exert a lot of pressure on the drill bit—as much as it will bear. Small bits can be a challenge because pressure can cause them to bend and break, but you can put a lot of pressure on any drill bit that's ¼in or larger.
The hardest standard drill bits you can buy are Solid Tungsten Carbide. They can reach hardness levels up to 82 HRC on the Rockwell C scale. Designed for industrial use, they effortlessly slice through hardened steel, cast iron, and masonry, but are highly brittle and require rigid machinery like a drill press.
Superabrasive, diamond plated tools have a major edge over carbide—longevity and cut-rate set diamond tools apart from the rest. Initially, a diamond tool will cost more money, but this investment goes toward the extended life of the bit. Additionally, diamond tools have a closer cut tolerance than carbide does.
Carbide is significantly harder, more wear-resistant, and retains its edge at higher temperatures, making it the stronger material for cutting and machining. However, cobalt is much tougher and more flexible.
Always drill metal on a slow speed combined with firm, steady pressure. High speeds generate excessive friction and heat, which will instantly burn and dull your drill bit.
For thick steel, the best choice is a Cobalt (M35 or M42) drill bit. Made of high-speed steel alloyed with 5% to 8% cobalt, these bits are highly heat-resistant, incredibly tough, and can be resharpened. Avoid standard black oxide or titanium-coated bits, as they will quickly burn out and dull in thick steel.
DeWalt drill bits are highly rated for offering an excellent balance between affordability and performance. They are ideal for DIYers and professionals tackling wood, plastic, and mild metals. While premium brands like Bosch or Viking may edge them out in extreme endurance, DeWalt is widely considered a great value.