Guide to Optimizing Zirconium Machining and Forming Processes

In harsh chemical environments where equipment frequently fails due to corrosion—leading to reduced productivity and soaring maintenance costs—zirconium emerges as an exceptional solution. This article explores the processing and forming techniques for zirconium and its alloys, enabling industries to maximize their performance advantages.

Zirconium is a hard, lustrous, silver-gray metal renowned for its outstanding corrosion resistance, making it the material of choice for chemical processing equipment. In non-nuclear applications, zirconium primarily exists in two alloy forms:

• ASTM R60702 (Zr 702): Unalloyed pure zirconium
• ASTM R60705: Zirconium-niobium alloy containing 2.0-3.0% niobium

The physical and mechanical properties of zirconium and its alloys (detailed in Table 1) make them particularly effective in applications requiring high corrosion resistance.

Zirconium offers good ductility and machinability using standard workshop equipment with minor modifications. However, three fundamental principles must be observed:

1. Low Cutting Speeds: Avoid excessive speeds to minimize heat generation and work hardening
2. High Feed Rates: Produce coarse chips to reduce tool wear
3. Adequate Cooling: Use water-soluble oil lubricants to lower cutting temperatures

Due to its tendency for galling and work hardening, zirconium requires larger tool clearance angles than normal. Maintaining sharp tools is crucial, as fine chips pose a fire hazard (see Safety section).

Zirconium turning requires no special equipment. Recommended parameters are shown in Tables 2 and 3. Tool rake angles should range between +15° to +60°.

Both vertical and horizontal milling perform well with zirconium. Climb milling is preferred to penetrate work-hardened surfaces. Tools must remain sharp with adequate coolant flow. Tables 4-9 provide detailed milling parameters.

Standard 118° thin-web drill bits with coolant produce satisfactory results. Rigid backing prevents burring at exit points. Tables 10-13 outline drilling, boring, tapping, and reaming specifications.

Both wheel and belt grinding are effective. Silicon carbide wheels outperform aluminum oxide. Grinding oils yield better results than water-soluble fluids. Tables 14-17 present grinding parameters.

Power hacksaws perform best with coarse-tooth (3T) high-speed steel blades. Band saws require 0.042" raker-set blades with coolant. Tables 18-20 contain sawing recommendations.

Zirconium can be formed using standard equipment but reacts with atmospheric gases at high temperatures and tends to gall.

A. Bending: Minimum bend radii are 5T at room temperature and 3T at 200°C. Tube bending requires 3x OD radius minimum.

B. Punching: Requires high blankholder pressure with 1-2% metal thickness clearance for optimal results.

C. Drawing & Spinning: Good formability despite work hardening characteristics. Large radii and gradual section changes are essential.

Zirconium's pyrophoric nature requires special precautions. While bulk material is safe, fine chips and turnings readily ignite at high temperatures. Storage in water-covered containers is recommended. Never use water or standard extinguishers on zirconium fires—only dry sand, graphite powder, or Metal-X powder.