10 Best Drill Bits To Drill Hardened Steel in 2026

An impact-rated shank and a titanium nitride coating make this set ready for the hammering action of an impact driver, a tool many people already own for driving screws. That design, combined with a no-skate tip for accurate starts, means you can drill hardened steel without hunting for a dedicated drill press. It’s a straightforward, no-fuss set for the user who needs a few reliable sizes and wants to use their most powerful driver for the job.

The set contains five bits, which covers a limited range of sizes compared to larger kits like the 14-piece Bosch CO14B or the 21-piece Crosstar sets. Its compact size, at just over five inches long, makes it easy to store in a small toolbox. Laser marking on each bit clearly identifies the diameter.

An 8% cobalt M42 alloy gives these bits ten times the life of standard ones, which means fewer replacements for frequent metalworkers. The surface-hardened tip and high heat resistance target tough materials like stainless steel, cast iron, and titanium. Bosch’s thick web-helix design provides additional stability, reducing walk and chatter during demanding applications.

Reviewers of Bosch Cobalt 42 bits report they can wear out more quickly when used on work-hardened steel or without cutting fluid. While the M42 alloy delivers durable performance for many hardened steel jobs, proper technique and coolant influence longevity. At around five dollars for a single 1/4-inch bit, the set represents an affordable high-cobalt option.

A 1/4-inch hex shank and impact rating let you drop these bits straight into an impact driver for use on materials like ferrous metal and stainless steel, preventing shank slippage under torque. The titanium nitride coating lasts 2.5 times longer than non-coated bits, which reduces wear and the need for frequent bit changes. A 135-degree split point geometry provides faster starts and less walking on the surface before the hole begins.

The trade-off is in specialization. While versatile across materials like wood, plastic, and metal, the 14-piece count focuses on common sizes. For the occasional stainless steel job mixed with wood and plastic, these are excellent. The set is built for users who rely on an impact driver, offering quick bit changes and the durability of a titanium nitride coating.

The TiAlN coating’s ability to withstand 800°C is the defining feature here. This extreme heat resistance directly translates to less friction and a longer-lasting cutting edge when you’re pushing through hardened steel or titanium. For anyone regularly drilling tough alloys, this coating means fewer bit changes and more consistent performance over time. The M35 cobalt core and the aggressive triple-flute geometry are built to support that coating, tackling materials up to 60 HRC with improved chip clearance.

This set is crafted from M35 cobalt steel with a TiAlN coating, engineered to drill hardened materials up to 60 HRC. That means it can handle tough jobs on stainless steel or titanium alloys without degrading quickly. Its titanium aluminum nitride coating withstands temperatures up to 1472°F, drastically reducing heat buildup for a longer tool life compared to standard coatings. The innovative triple-flute design, used on most bits, provides about 40% better chip ejection for cooler operation. It also delivers a superior hole finish and reduced bit walk during standard depth-of-cut work.

This set arrives in a case just over four inches long, so it slides easily into a tool drawer or a small bag. Inside, the M35 cobalt bits are hardened and polished, which helps them stay sharp for cutting stainless steel and other hard metals. A 135-degree point tip on each bit aids in self-centering to prevent walk-off, and the twist design promotes faster chip removal during use.

The included sizes range from 1/16 inch to 1/4 inch, providing a variety for different tasks. Compared to other sets, like the Bosch CO14B, this one has a smaller maximum diameter. Its jobber-length bits and compact case prioritize organized storage over a wider size selection or longer reach.

Withstanding friction temperatures over 1,472°F, the TiAlN coating is the key differentiator, forming a protective barrier that drastically reduces wear during the intense heat of drilling thin metals. This set is engineered specifically for the challenges of sheet metal and stainless steel, where rapid overheating causes standard bits to dull prematurely. The self-centering Pilot Point tip eliminates frustrating bit walk on curved or hard surfaces, allowing for cleaner holes with minimal burrs and significantly less post-processing time. For anyone regularly tackling precise, repeated drilling in thin, hardened materials that quickly work-harden, this focus on heat resistance and clean starts is precisely what delivers professional results.

Its tip geometry is optimized for thin stock. This focus means it may not be the most versatile set for general shop use across varied thicknesses. For a more general-purpose cobalt set that handles a wider range of material thicknesses, consider the Bosch CO14B Cobalt M42 set. The Crosstar set excels in its niche, delivering longevity and precision where thin, gummy metals would quickly destroy a less specialized bit.

A 29-piece set covering 1/16-inch to 1/2-inch in 1/64-inch increments means you’re equipped for nearly any hole size needed in steel fabrication or repair. The 5% cobalt alloy is the key here, letting you push into hardened material without the bit softening from friction heat. This comprehensive range suits a shop that needs a single, go-to set for everything from small pilot holes to large clearance bolts, eliminating the hunt for a specific bit mid-project.

The storage case measures 11.6 inches long, a size that dictates storing it on a workbench or in a toolbox drawer. Unlike the Makita Impact Gold set, these bits lack a hex shank for direct use in many impact drivers. Their heavy-duty web construction is a feature intended to enhance strength during demanding drilling tasks.

The 135-degree split stepped point is the key feature here. That aggressive geometry bites into an existing hole’s edge immediately, letting you cleanly step up the size without the bit wandering. It’s a set built for the mechanic or fabricator who frequently needs to open up a bolt hole or modify a bracket, not just start from scratch. The gold oxide coating on the cobalt steel helps manage the intense heat generated when working with hardened metals, which increases the tool’s lifespan.

You trade some versatility for this specialized performance. For drilling brand-new holes in flat stock, a traditional pilot-point cobalt set like the Bosch CO14B might offer a more straightforward experience. But when the job calls for precise enlargement, this Drill America set’s design eliminates the need for a separate reamer or a perfectly centered pilot hole. It’s a time-saver that lives up to the brand’s industrial heritage, putting a professional-grade solution for a specific problem into a well-organized case.

A 29-piece range means you can step up sizes precisely when drilling through hardened steel, without hunting for the right bit mid-job. The cobalt construction handles the heat and abrasion of tough alloys, and the organized case keeps every size in its place after use.

Its comprehensive case is large and heavy, which affects portability. This makes it a bench-top solution, not something you’d toss in a compact service bag. For a technician who needs a capable but more mobile set for on-site repairs, a compact option like the NordWolf M35 Cobalt Stubby Drill Bit Set with its hex shank might be a better fit. That option, however, offers far fewer sizes.

With a maximum length of just 2.32 inches, these stubby bits are designed specifically for accessing hard-to-reach and tight spaces where standard-length drill bits cannot fit. They are made from M35 cobalt steel for drilling into stainless steel and various hardened metals. The 1/4-inch hex shank is compatible with quick-change chucks and impact drivers, allowing for use without swapping tools.

The trade-off for that ultra-compact profile is reach; you won’t be drilling through thick material or accessing a spot that requires any depth. This set is also a focused toolkit, not a complete one. For a broader selection of sizes in a standard length, the MACXCOIP M35 Cobalt set offers thirteen bits from 1/16″ to 1/4″. With that set, however, you lose the stubby design and hex-shank impact driver compatibility that makes the NordWolf unique.