Hardenability
Materials Science · FE Reference Handbook section
Handbook notes for this section
Definitions and conditions exactly as the handbook states them.
- Hardness: Resistance to penetration. Measured by denting a material under known load and measuring the size of the dent.
- Hardenability: The "ease" with which hardness can be obtained.
- JOMINY HARDENABILITY CURVES FOR SIX STEELS
- The following two graphs show cooling curves for four different positions in the bar.
- These positions are shown in the following figure.
- COOLING RATES FOR BARS QUENCHED IN AGITATED WATER
- COOLING RATES FOR BARS QUENCHED IN AGITATED OIL
Core formulas for this FE topic
Definitions, applicability, units, assumptions and worked examples for each relation.
Worked exam-style examples
The four ways this section is written on the real exam — thoughts first, then equations, then substitution.
A metallurgist evaluates the hardenability of a steel alloy using Jominy end-quench data. Given surface hardness (HRC0) = 53.5000 HRC; hardness gradient (k) = 11.5000 HRC/in; Jominy distance (d) = 2.4000 in, determine the hardness at distance d (HRC) in HRC.
Given
Find
hardness at distance d (HRC), in HRC
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except HRC is given, so isolate HRC symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for HRC:
Step 3 — List the givens: surface hardness (HRC0) = 53.5000 HRC, hardness gradient (k) = 11.5000 HRC/in, Jominy distance (d) = 2.4000 in.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning HRC = 25.9000 HRC to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 51.8000 — kept a factor of two that cancels in the correct rearrangement.
- 12.9500 — dropped that same factor in the other direction.
- 28.4900 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability
An engineer selects a steel grade based on its hardenability requirement. Given hardness gradient (k) = 6.5000 HRC/in; Jominy distance (d) = 0.6000 in; hardness at distance d (HRC) = 10.2000 HRC, determine the surface hardness (HRC0) in HRC.
Given
Find
surface hardness (HRC0), in HRC
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except HRC0 is given, so isolate HRC0 symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for HRC0:
Step 3 — List the givens: hardness gradient (k) = 6.5000 HRC/in, Jominy distance (d) = 0.6000 in, hardness at distance d (HRC) = 10.2000 HRC.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning HRC0 = 14.1000 HRC to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 28.2000 — kept a factor of two that cancels in the correct rearrangement.
- 7.0500 — dropped that same factor in the other direction.
- 15.5100 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability
The hardenability curve shows hardness dropping with distance from the quenched face. Given surface hardness (HRC0) = 54.0000 HRC; hardness gradient (k) = 7.0000 HRC/in; hardness at distance d (HRC) = 15.3000 HRC, determine the Jominy distance (d) in in.
Given
Find
Jominy distance (d), in in
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except d is given, so isolate d symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for d:
Step 3 — List the givens: surface hardness (HRC0) = 54.0000 HRC, hardness gradient (k) = 7.0000 HRC/in, hardness at distance d (HRC) = 15.3000 HRC.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning d = 5.5286 in to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 11.0571 — kept a factor of two that cancels in the correct rearrangement.
- 2.7643 — dropped that same factor in the other direction.
- 6.0814 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability
A metallurgist evaluates the hardenability of a steel alloy using Jominy end-quench data. Given surface hardness (HRC0) = 52.0000 HRC; hardness gradient (k) = 5.0000 HRC/in; Jominy distance (d) = 0.8000 in, determine the hardness at distance d (HRC) in HRC.
Given
Find
hardness at distance d (HRC), in HRC
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except HRC is given, so isolate HRC symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for HRC:
Step 3 — List the givens: surface hardness (HRC0) = 52.0000 HRC, hardness gradient (k) = 5.0000 HRC/in, Jominy distance (d) = 0.8000 in.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning HRC = 48.0000 HRC to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 96.0000 — kept a factor of two that cancels in the correct rearrangement.
- 24.0000 — dropped that same factor in the other direction.
- 52.8000 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability
An engineer selects a steel grade based on its hardenability requirement. Given hardness gradient (k) = 5.5000 HRC/in; Jominy distance (d) = 2.6000 in; hardness at distance d (HRC) = 23.0000 HRC, determine the surface hardness (HRC0) in HRC.
Given
Find
surface hardness (HRC0), in HRC
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except HRC0 is given, so isolate HRC0 symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for HRC0:
Step 3 — List the givens: hardness gradient (k) = 5.5000 HRC/in, Jominy distance (d) = 2.6000 in, hardness at distance d (HRC) = 23.0000 HRC.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning HRC0 = 37.3000 HRC to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 74.6000 — kept a factor of two that cancels in the correct rearrangement.
- 18.6500 — dropped that same factor in the other direction.
- 41.0300 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability
The hardenability curve shows hardness dropping with distance from the quenched face. Given surface hardness (HRC0) = 52.0000 HRC; hardness gradient (k) = 12.0000 HRC/in; hardness at distance d (HRC) = 34.4000 HRC, determine the Jominy distance (d) in in.
Given
Find
Jominy distance (d), in in
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except d is given, so isolate d symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for d:
Step 3 — List the givens: surface hardness (HRC0) = 52.0000 HRC, hardness gradient (k) = 12.0000 HRC/in, hardness at distance d (HRC) = 34.4000 HRC.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning d = 1.4667 in to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 2.9333 — kept a factor of two that cancels in the correct rearrangement.
- 0.7333 — dropped that same factor in the other direction.
- 1.6133 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability
A metallurgist evaluates the hardenability of a steel alloy using Jominy end-quench data. Given surface hardness (HRC0) = 55.5000 HRC; hardness gradient (k) = 4.5000 HRC/in; Jominy distance (d) = 0.6000 in, determine the hardness at distance d (HRC) in HRC.
Given
Find
hardness at distance d (HRC), in HRC
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except HRC is given, so isolate HRC symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for HRC:
Step 3 — List the givens: surface hardness (HRC0) = 55.5000 HRC, hardness gradient (k) = 4.5000 HRC/in, Jominy distance (d) = 0.6000 in.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning HRC = 52.8000 HRC to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 105.6 — kept a factor of two that cancels in the correct rearrangement.
- 26.4000 — dropped that same factor in the other direction.
- 58.0800 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability
An engineer selects a steel grade based on its hardenability requirement. Given hardness gradient (k) = 5.0000 HRC/in; Jominy distance (d) = 1.8000 in; hardness at distance d (HRC) = 40.4000 HRC, determine the surface hardness (HRC0) in HRC.
Given
Find
surface hardness (HRC0), in HRC
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except HRC0 is given, so isolate HRC0 symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for HRC0:
Step 3 — List the givens: hardness gradient (k) = 5.0000 HRC/in, Jominy distance (d) = 1.8000 in, hardness at distance d (HRC) = 40.4000 HRC.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning HRC0 = 49.4000 HRC to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 98.8000 — kept a factor of two that cancels in the correct rearrangement.
- 24.7000 — dropped that same factor in the other direction.
- 54.3400 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability
The hardenability curve shows hardness dropping with distance from the quenched face. Given surface hardness (HRC0) = 61.5000 HRC; hardness gradient (k) = 5.0000 HRC/in; hardness at distance d (HRC) = 30.6000 HRC, determine the Jominy distance (d) in in.
Given
Find
Jominy distance (d), in in
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except d is given, so isolate d symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for d:
Step 3 — List the givens: surface hardness (HRC0) = 61.5000 HRC, hardness gradient (k) = 5.0000 HRC/in, hardness at distance d (HRC) = 30.6000 HRC.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning d = 6.1800 in to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 12.3600 — kept a factor of two that cancels in the correct rearrangement.
- 3.0900 — dropped that same factor in the other direction.
- 6.7980 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability
A metallurgist evaluates the hardenability of a steel alloy using Jominy end-quench data. Given surface hardness (HRC0) = 60.5000 HRC; hardness gradient (k) = 8.5000 HRC/in; Jominy distance (d) = 2.2000 in, determine the hardness at distance d (HRC) in HRC.
Given
Find
hardness at distance d (HRC), in HRC
Start with the thinking
- The governing relation printed in this handbook section is Hardenability — Jominy distance to hardness ratio.
- Everything except HRC is given, so isolate HRC symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Hardenability describes how hardness decreases with distance from the quenched end in a Jominy test.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for HRC:
Step 3 — List the givens: surface hardness (HRC0) = 60.5000 HRC, hardness gradient (k) = 8.5000 HRC/in, Jominy distance (d) = 2.2000 in.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning HRC = 41.8000 HRC to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 83.6000 — kept a factor of two that cancels in the correct rearrangement.
- 20.9000 — dropped that same factor in the other direction.
- 45.9800 — rounded an intermediate value before the final step.
Reference: FE Handbook — Hardenability