Specific cutting energy and machinability The specific cutting energy used for comparing machinability of metals depends primarily on which material characteristics?

Introduction / Context:
Specific cutting energy (energy per unit volume removed) reflects how difficult it is to shear and remove material. It serves as a practical basis for comparing machinability across alloys and heat treatments under similar cutting conditions.

Given Data / Assumptions:

• Orthogonal cutting model insights apply to practical 3D cutting.
• Steady cutting conditions: tool geometry, speed, feed, and depth fixed for comparison.

Concept / Approach:
Specific cutting energy captures both material resistance to shear deformation and frictional losses. Friction at the tool–chip interface elevates the required energy. Microstructure controls flow stress (e.g., pearlite vs ferrite, precipitates), while work hardening raises flow stress with strain, further increasing energy demand.

Step-by-Step Solution:
Relate cutting energy = shear energy + friction energy.Coefficient of friction ↑ → interface friction ↑ → energy ↑ (A).Microstructure affects yield/flow stress and chip formation → energy varies (B).Strain hardening exponent n influences stress with plastic strain → energy varies (C).Therefore, all listed factors influence specific cutting energy → (D).

Verification / Alternative check:
Empirical data show higher specific energies for hardened or heavily work-hardening alloys; free-machining grades with sulfides reduce friction and energy.

Why Other Options Are Wrong:
(E) is too narrow; hardness alone does not fully predict cutting energy without considering microstructure and frictional behavior.

Common Pitfalls:
Comparing specific energy across tests with different tool geometries; ignoring coolant effects that alter friction; overlooking chip thickness effect on apparent energy.

Final Answer:
all of these