Simple Ways to Distinguish Tungsten Steel from Highspeed Steel

When working with metal cutting tools, correctly identifying whether they're made of wear-resistant tungsten carbide (hard metal) or tough high-speed steel is crucial for selecting appropriate machining parameters. An incorrect choice may lead to premature tool wear or even chipping, resulting in unnecessary losses. While professional testing equipment provides the most accurate results, there are several practical methods to distinguish these materials without specialized tools.

1. Hardness Test (Scratch Method)

The most straightforward approach leverages the significant hardness difference between the materials. Tungsten carbide typically measures 90-92 HRA, while high-speed steel ranges between 62-67 HRC.

• Select an inconspicuous area on each tool for testing
• Attempt to scratch each material with the other
• The material that leaves a visible scratch is the harder one (likely tungsten carbide)
• High-speed steel will rarely mark tungsten carbide surfaces

Note that this method is somewhat destructive and should be performed on non-critical tool sections.

2. Acoustic Test (Tapping Method)

The materials produce distinct sounds when struck due to differences in density and hardness:

• Tungsten carbide emits a high-pitched, glass-like ringing tone
• High-speed steel produces a duller, lower-frequency sound

This technique requires some practice to master. For best results, compare known samples of each material to develop an auditory reference.

3. Visual Inspection (Spark Test)

When ground on a bench grinder, the materials generate characteristic spark patterns:

• Tungsten carbide: Produces sparse, dark red sparks with short, thick trajectories
• High-speed steel: Creates abundant bright yellow sparks with long, thin paths that often fork at the ends

Always wear proper eye protection when performing spark tests. The technique becomes more reliable with experience comparing known samples.

These field methods provide reasonable accuracy for most practical applications. For critical applications requiring definitive identification, professional hardness testers or material analysis equipment should be employed. Combining multiple test methods increases identification confidence and helps prevent costly material misclassification errors.