Chapter 13, Problem 13.33P

Interpretation Introduction

(a)

Interpretation:

The hardness of $4340$ steel needs to be determined.

  

Figure $1$

Concept Introduction:

Hardness is a material property of a metal due to which material resist the plastic reformation. Plastic reformation means material reformation which undergoes non-reversible change. Hardness is a material property to resistance to twisting, scraping or cutting. Hardness is not constant or fixed for all material, but it depends upon strength and plasticity of metal, material hardness is expressed in terms of hardness number.

Answer to Problem 13.33P

The hardness of $4340$ steel is $\text{HRC}\text{60}$

Explanation of Solution

Given Information:

Jominy distance	Cooling rate (${}^{0}c/sec$)
$\frac{3}{16}$	$50$
$\frac{4}{16}$	$36$
$\frac{6}{16}$	$22$
$\frac{8}{16}$	$15$
$\frac{10}{16}$	$10$

Calculations:

From the given diagram and table, the $4340$ steel cannot obtain hardness near to $\text{40}$. So the hardness would be larger than 40HRC range. Thus, the hardnessof $4340$ steel is $\text{HRC}\text{60}$

Interpretation Introduction

(b)

Interpretation:

The cooling rate and distance to hardness of $\text{8640}$ steel needs to be determined.

  

Figure $2$

Concept Introduction:

Hardness is a material property of a metal due to which material resist the plastic reformation. Plastic reformation means material reformation which undergoes non-reversible change. Hardness is a material property to resistance to twisting, scraping or cutting. Hardness is not constant or fixed for all material, but it depends upon strength and plasticity of metal, material hardness is expressed in terms of hardness number.

Answer to Problem 13.33P

Hardness level ranges from $\text{28}\text{.5}$ mm to $\text{31}\text{.8}$ mm and the cooling rate from ${\text{3}}^{0}C$ to $4^{0}C$

Explanation of Solution

Given Information:

Jominy distance	Cooling rate (${}^{0}c/sec$)
$\frac{3}{16}$	$50$
$\frac{4}{16}$	$36$
$\frac{6}{16}$	$22$
$\frac{8}{16}$	$15$
$\frac{10}{16}$	$10$

Calculations:

  

Figure $3$

The equation byjominy is $\frac{1^{\text{th}}}{\text{15}}$ of an inch and from the figure, the hardenability curve the hardness obtained is in the range of $\text{28}\text{.5}$ mm to $\text{31}\text{.8}$ mm.

By using the Jominy table, the cooling rate obtained is ${\text{3}}^{\text{0}}\text{C}$ to ${\text{4}}^{\text{0}}\text{C}$

Interpretation Introduction

(c)

Interpretation:

The cooling rate and distance to the hardness of $9310$ steel needs to be determined.

  

Figure $4$

Concept Introduction:

Hardness is a material property of a metal due to which material resist the plastic reformation. Plastic reformation means material reformation which undergoes non-reversible change. Hardness is a material property to resistance to twisting, scraping or cutting. Hardness is not constant or fixed for all material, but it depends upon strength and plasticity of metal, material hardness is expressed in terms of hardness number.

Answer to Problem 13.33P

The distance to the hardness of $9310$ steel is $15.8$ mm to $19$ mm and cooling rate is from $8^{0}C$ to ${10}^{0}C$

Explanation of Solution

Given Information:

Jominy distance	Cooling rate (${}^{0}C/sec$)
$\frac{3}{16}$	$50$
$\frac{4}{16}$	$36$
$\frac{6}{16}$	$22$
$\frac{8}{16}$	$15$
$\frac{10}{16}$	$10$

Calculations:

  

Figure $5$

The equation byjominy is $\frac{1^{\text{th}}}{\text{15}}$ of an inchand from the figure, the hardenability curve the hardness obtained is in the range of $15.8$ mm to $19$ mm

By using the Jominy table, the cooling rate obtained is $8^{0}C$ to ${10}^{0}C$

Interpretation Introduction

(d)

Interpretation:

The cooling rate and distance tothehardness of $4320$ steel needs to be determined.

  

Figure $6$

Concept Introduction:

Hardness is a material property of a metal due to which material resist the plastic reformation. Plastic reformation means material reformation which undergoes non-reversible change. Hardness is a material property to resistance to twisting, scraping or cutting. Hardness is not constant or fixed for all material, but it depends upon strength and plasticity of metal, material hardness is expressed in terms of hardness number.

Answer to Problem 13.33P

The distance to the hardness of $4320$ steel is $38$ mm to $40$ mm and cooling rate is from ${\text{22}}^{\text{0}}\text{C}$

Explanation of Solution

Given Information:

Jominy distance	Cooling rate (${}^{0}c/sec$)
$\frac{3}{16}$	$50$
$\frac{4}{16}$	$36$
$\frac{6}{16}$	$22$
$\frac{8}{16}$	$15$
$\frac{10}{16}$	$10$

Calculations:

  

Figure $7$

The equation byjominy is, $\frac{1^{\text{th}}}{\text{15}}$ of an inchand from the figure, the hardenability curve the hardness obtained is in the range of $38$ mm to $40$ mm

By using the Jominy table, the cooling rate obtained is ${\text{22}}^{\text{0}}\text{C}$.

Interpretation Introduction

(e)

Interpretation:

The cooling rate and distance tothehardness of $1050$ steel needs to be determined.

  

Figure $\text{8}$

Concept Introduction:

Hardness is a material property of a metal due to which material resist the plastic reformation. Plastic reformation means material reformation which undergoes non-reversible change. Hardness is a material property to resistance to twisting, scraping or cutting. Hardness is not constant or fixed for all material, but it depends upon strength and plasticity of metal, material hardness is expressed in terms of hardness number.

Answer to Problem 13.33P

The distance to the hardness of $1050$ steel is $6.4$ mm to $7.2$ mm and cooling rate is from ${32}^{0}C$ to ${36}^{0}C$

Explanation of Solution

Given Information:

Jominy distance	Cooling rate (${}^{0}c/sec$)
$\frac{3}{16}$	$50$
$\frac{4}{16}$	$36$
$\frac{6}{16}$	$22$
$\frac{8}{16}$	$15$
$\frac{10}{16}$	$10$

Calculations:

  

Figure $\text{9}$

The equation byjominy is, $\frac{1^{\text{th}}}{\text{15}}$ of an inchand from the figure, the hardenability curve the hardness obtained is in the range of $6.4$ mm to $7.2$ mm

By using the Jominy table, the cooling rate obtained is ${\text{32}}^{\text{0}}\text{C}$ to ${\text{36}}^{\text{0}}\text{C}$

Interpretation Introduction

(f)

Interpretation:

The cooling rate and distance to hardness of $1080$ steel needs to be determined.

  

Figure $\text{10}$

Concept Introduction:

Hardness is a material property of a metal due to which material resist the plastic reformation. Plastic reformation means material reformation which undergoes non-reversible change. Hardness is a material property to resistance to twisting, scraping or cutting. Hardness is not constant or fixed for all material, but it depends upon strength and plasticity of metal, material hardness is expressed in terms of hardness number.

Answer to Problem 13.33P

The distance tothehardness of $1080$ steel is $9.5$ mm to $11$ mm and cooling rate is from ${\text{17}}^{\text{0}}\text{C}$ to ${\text{22}}^{\text{0}}\text{C}$

Explanation of Solution

Given Information:

Jominy distance	Cooling rate (${}^{0}c/sec$)
$\frac{3}{16}$	$50$
$\frac{4}{16}$	$36$
$\frac{6}{16}$	$22$
$\frac{8}{16}$	$15$
$\frac{10}{16}$	$10$

Calculations:

  

Figure $\text{11}$

The equation byjominy is, $\frac{1^{\text{th}}}{\text{15}}$ of an inch and from the figure, the hardenability curve the hardness obtained is in the range of $9.5$ mm to $11$ mm.

By using the Jominy table, the cooling rate obtained is ${\text{17}}^{\text{0}}\text{C}$ to ${\text{22}}^{\text{0}}\text{C}$.