Cobalt-based hard-facing alloys — stellite Stellite, a well-known hard-facing alloy system for wear and corrosion resistance, is primarily composed of which elements?

Introduction / Context:
Stellite is a family of cobalt-based hard-facing alloys widely used for valves, seats, cutting tools, and wear surfaces where abrasion, corrosion, and high-temperature strength are critical.

Given Data / Assumptions:

• Trade name: Stellite.
• Target properties: wear resistance, hot hardness, corrosion resistance.

Concept / Approach:
The core chemistry of stellite alloys features a cobalt matrix strengthened by chromium and tungsten (often with carbon to form carbides). Chromium enhances corrosion/oxidation resistance, while tungsten promotes carbide formation and hot hardness, delivering superior wear performance at elevated temperatures.

Step-by-Step Solution:
Identify hallmark elements: Co–Cr–W system.Relate chemistry to properties: Cr for corrosion/oxidation, W for carbides/hot hardness, Co matrix for toughness at temperature.Therefore, choose cobalt, chromium and tungsten.

Verification / Alternative check:
Materials datasheets and welding consumable catalogs list Co–Cr–W as the base for Stellite grades (e.g., Stellite 6).

Why Other Options Are Wrong:

• Zn–Cu–Ni / Zn–Al–Ni: non-stellite compositions.
• Ni–Co–V: can form other superalloys, but not classic stellite chemistry.

Common Pitfalls:

• Assuming all hard-facing alloys are nickel-based; stellite is cobalt-based.

Final Answer:
Cobalt, chromium and tungsten