Waterjet Cutting Titanium: Grade 2, Grade 5 (Ti-6Al-4V), and Grade 23

When titanium is heated above roughly 1100-1300 F in air, the surface absorbs oxygen and nitrogen and forms alpha case, an oxygen-stabilized layer that is hard, brittle, and a fatigue-crack initiator. In aerospace and medical service that layer is a defect; specs frequently require it to be machined or chemically milled away. Laser and plasma cutting of titanium produce exactly this contaminated edge, plus a recast layer, so thermally cut titanium usually carries a stock allowance that must be removed. Abrasive waterjet cuts titanium cold by erosion, so no alpha case forms at the edge, no oxygen pickup occurs, and the metallurgy stays clean to the kerf wall. This is the central reason titanium and waterjet pair so well: you get a contamination-free blank without the chemical milling or skim machining that thermal cutting forces. For fatigue-critical airframe and implant parts, that clean edge is not a convenience, it is a requirement.

Grade 2 is commercially pure titanium, relatively soft and ductile, and it cuts the fastest of the three on a waterjet. It is common in chemical processing, marine, and medical hardware where strength is secondary to corrosion resistance and formability. Grade 5, Ti-6Al-4V, is the alpha-beta workhorse alloy and the most-cut titanium overall; it is stronger and tougher, so it cuts maybe 20-30 percent slower than Grade 2 at equal thickness, but the cold cut is doubly valuable because Ti-6Al-4V is the alloy aerospace and orthopedics build with. Grade 23, Ti-6Al-4V ELI (extra low interstitials), is the high-purity, high-toughness variant used for implants and fracture-critical aerospace parts. It cuts much like Grade 5 on the waterjet, and the cold process protects the very thing that makes ELI valuable: its low interstitial oxygen and nitrogen content. Any thermal pickup would defeat the purpose of buying ELI in the first place, so waterjet is the natural cutting method for Grade 23 blanks destined for the machine shop.

On 0.25 inch Ti-6Al-4V a quality waterjet holds around +/-0.005 inch; at 0.5 inch expect +/-0.005 to +/-0.008 inch, and at 1 inch +/-0.010 inch with taper unless corrected by a tilting head. Titanium is tough, so cut speeds are slower than steel and the lower edge shows striations. Most titanium blanks are quoted Q3, since the part will almost always be finish-machined anyway. Because titanium parts are valuable and usually machined after cutting, the practical workflow is to waterjet a net-near blank with 0.030-0.060 inch of stock on profiled surfaces and machine to final dimension. The waterjet saves enormous material versus sawing rectangular blanks and removing the rest, which matters when Ti-6Al-4V plate runs many times the cost of steel. The clean, alpha-case-free edge means the finish machining only has to remove the stock you intended, not a contaminated layer on top.

Titanium plate is expensive, often fifteen to thirty times the cost of mild steel per pound, so material yield dominates the economics. Waterjet's tooling-free nesting lets you pack profiled parts tightly and recover the web as remnant, which can save more money than the cut itself costs. The cut is slow and garnet consumption is normal, so machine time is real but secondary to material on titanium jobs. The pairing pays off most clearly for aerospace detail parts, medical implant and instrument blanks, and energy hardware in titanium where the alternative is chemical milling after a thermal cut or wasteful saw blanking. Lead times run a few days to a couple of weeks depending on plate availability and quantity. When the part is titanium and will be machined or fatigue-loaded, waterjet blanking is close to the default first operation, and it is rarely the wrong choice.