Tool material characteristics Carbon tool steels exhibit low heat resistance and low wear resistance compared with HSS and carbides. Is this statement correct?

Difficulty: Easy

Correct Answer: Correct

Explanation:


Introduction / Context:
Tool material selection balances hot hardness, wear resistance, toughness, and cost. Carbon tool steels were historically common but are now limited to low-speed applications due to poor hot-strength and rapid softening at modest temperatures.



Given Data / Assumptions:

  • Carbon tool steels lose hardness rapidly above roughly 200–250 °C.
  • Comparators: high-speed steel (HSS), cast/cemented carbides, ceramics.
  • Operations: general cutting where heat generation is significant.


Concept / Approach:
Hot hardness describes a material's ability to retain hardness at elevated temperatures. Carbon tool steels temper easily and cannot maintain an edge under modern cutting speeds, leading to accelerated flank wear and built-up edge formation.



Step-by-Step Solution:

Assess heat resistance: carbon tool steels soften at relatively low temperatures → low heat resistance.Assess wear resistance: softening plus limited alloy carbides → poorer wear resistance than HSS/carbides.Conclusion: the statement is correct.


Verification / Alternative check:
Tool life curves (Taylor's equation) show dramatically lower permissible cutting speeds for carbon steels versus HSS/carbide for the same life.



Why Other Options Are Wrong:
Claiming incorrectness or exceptions (interrupted cuts, high temperatures) misunderstands the fundamental deficiency in hot hardness and wear resistance.



Common Pitfalls:
Using carbon tool steel where heat cannot be controlled; choose HSS or carbide for sustained industrial speeds.



Final Answer:

Correct

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