High-speed steels (HSS) — tungsten content trend In traditional tungsten-type high-speed steels used for cutting tools, the percentage of tungsten present is generally the __________ among the principal alloying elements (compared with chromium and vanadium).

Introduction / Context:
High-speed steels are engineered tool steels designed to retain high hardness at elevated temperature, a property often called red hardness. The classic tungsten series (T-grades) achieves this through a high proportion of tungsten, supported by chromium and a small amount of vanadium. Recognizing which element predominates helps learners connect composition with performance.

Given Data / Assumptions:

• We consider traditional tungsten-based HSS grades used for drills, taps, and milling cutters.
• Typical comparative elements: tungsten, chromium, and vanadium.
• Focus is on relative proportion, not exact percentages.

Concept / Approach:
Tungsten forms stable carbides that confer hot hardness and wear resistance. In T-series HSS, tungsten content is large, commonly around the high-teens by percent mass. Chromium is present at a moderate level to aid hardenability and oxidation resistance. Vanadium is deliberately kept low to moderate to refine grain size and provide abrasion resistance via vanadium carbides. Therefore, among these key alloying elements, tungsten is present in the highest proportion.

Step-by-Step Solution:
Identify the function of each element: W for hot hardness, Cr for hardenability and oxidation resistance, V for grain refinement and wear.Recall the relative levels in classic HSS: W is highest, Cr is moderate, V is lowest.Map to the blank: the tungsten percentage is the maximum among principal additions.Select the option that matches this relationship: maximum.

Verification / Alternative check:
Published compositions of T-series HSS list tungsten in the neighborhood of the high-teens percentage, with chromium around several percent and vanadium near one to a few percent. This confirms the qualitative ranking.

Why Other Options Are Wrong:

• Minimum, negligible, or zero: contradict the defining chemistry of tungsten-type HSS.
• Moderate: understates tungsten's dominant role in T-series grades.

Common Pitfalls:
Confusing tungsten-type HSS with molybdenum-type HSS; while Mo can substitute partly for W, the tungsten emphasis remains characteristic of the classic T-series.

Final Answer:
maximum