Materials and Forging in Axle Shop

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the maximum amount of carbon that can be added to molten iron before it becomes saturated?

4.33%

2.1%

0.025%

6.67% (correct)

Which phase of iron is an interstitial solid solution with the maximum solid solubility of 2.1% carbon?

Austenite (correct)

Alpha-Ferrite

Pearlite

Cementite

What is the purpose of using steel blooms in the Axle shop?

For creating body frames of railway cars.

For forging passenger car axles only.

For manufacturing steel blooms for a variety of locomotives. (correct)

For making electric motors exclusively.

At what temperature does austenite change its structure from FCC to BCC?

1394 degrees Celsius Signup and view all the answers

What is one of the key requirements for the steel used in manufacturing steel blooms?

It must be degassed under vacuum. Signup and view all the answers

What is the primary structural form of cementite?

Orthorhombic Signup and view all the answers

Which process is recommended for manufacturing forging hammers?

Quenched and tempered DIN 56NiCrMoV7 steel. Signup and view all the answers

What does yield strength represent in mechanical properties?

The stress at which permanent deformation begins. Signup and view all the answers

What is the hardness characteristic of pearlite in comparison to other phases?

Intermediate between alpha-ferrite and cementite Signup and view all the answers

What is contained in the crystalline structure of cementite?

6.67% carbon Signup and view all the answers

How is ductility measured?

Through percentage elongation. Signup and view all the answers

What type of tests are commonly conducted to assess mechanical properties?

Tensile, Compression, and Shear tests. Signup and view all the answers

Which phase is described as a lamellar mixture of austenite and cementite?

Pearlite Signup and view all the answers

What is meant by plastic deformation?

Permanent change in shape under stress. Signup and view all the answers

What is the maximum carbon solubility in alpha-ferrite at room temperature?

0.008% Signup and view all the answers

What material property does the tensile test provide maximum information about?

Mechanical properties. Signup and view all the answers

What is the appearance characteristic of pearlite?

Finger print-like appearance Signup and view all the answers

Which phase of iron contains the least amount of carbon solubility?

Alpha-Ferrite Signup and view all the answers

What is the formula for calculating yield strength?

$rac{P_y}{A_0}$ Signup and view all the answers

What should be available for the entire reclamation process of forging hammers?

Documented evidence. Signup and view all the answers

What does malleability refer to in materials?

The ability to undergo plastic deformation under compressive load. Signup and view all the answers

What occurs after the yield point of a material?

It starts to exhibit necking. Signup and view all the answers

How is ultimate tensile strength defined?

The maximum load carried before fracture. Signup and view all the answers

What is the ultimate load referred to in the context of tensile strength?

The load at which the specimen begins to neck. Signup and view all the answers

What does fracture strength represent?

The stress at the point of actual failure. Signup and view all the answers

What does toughness measure in materials?

The amount of energy a material can absorb before failure. Signup and view all the answers

Which structure does pure iron have at room temperature?

BCC structure. Signup and view all the answers

What happens to BCC iron at 912 degrees Celsius?

It transforms into FCC structure. Signup and view all the answers

What does the right vertical axis in the Iron carbon equilibrium diagram represent?

Only 6.67% carbon by weight. Signup and view all the answers

What temperature does FCC iron retain its structure until?

1394 degrees Celsius. Signup and view all the answers

Study Notes

Consumables Used in Axle Shop

Steel Blooms for forging Diesel/Electric locos and EMU Driving axles are sourced as per IRS R 43 and IRS R 16.
Steel blooms must be manufactured from basic electric arc furnace steel or equivalent, approved processes.
Hydrogen content in the liquid steel must be determined through a standard method using a LECO hydrogen analyzer.
Nitrogen content of the steel is also determined using a LECO nitrogen analyzer.

Forging Hammers

Forging hammers are used to make different steel axles and armature shafts for railways.
Hammers are made from DIN 56NiCrMoV7 steel, quenched and tempered to 34 HRC.
The reclamation process for the hammers must be fully documented and available to inspecting officials.

Mechanical Properties of Materials

Mechanical properties of materials are evaluated using various tests, including tensile, compression, shear, hardness, impact, and bending tests.
Tensile tests provide the most comprehensive information on mechanical properties.
Yield strength is the stress at which plastic deformation begins without a significant increase in load. (Yield strength = Py / Ao ) where Py = load at yield point, Ao = original area of cross section.
Ductility is a material's ability to undergo plastic deformation under tensile load. It is measured by percentage elongation. ( Percentage elongation = (L − Lo) / Lo * 100 , where L = post-test length, Lo = original length)
Malleability is a material's ability to undergo plastic deformation under compressive load.
Ultimate tensile strength is the maximum stress a material can withstand before fracturing, determined by dividing ultimate load (Pu) by the original cross-sectional area (Ao). (Ultimate tensile strength = Pu / Ao)
Fracture strength is the stress at which a material fractures.
Toughness is the ability of a material to absorb energy before fracturing.

Iron-Carbon Equilibrium Diagram

Iron is allotropic, meaning it can exist in more than one crystal structure depending on temperature.
Pure iron at room temperature is BCC (ferrite).
At 912°C, BCC iron transforms to FCC (austenite), which remains stable until 1394°C.
At 1538°C, iron melts.
The Iron-Carbon equilibrium diagram shows the different phases of iron-carbon alloys as a function of temperature and composition. The right-hand vertical axis represents carbon content (max 6.67%).
Various phases exist in the diagram, including ferrite, austenite, cementite, pearlite, and ledeburite.
These phases result from equilibrium cooling.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers key aspects of consumables, forging equipment, and mechanical properties of materials used in an axle shop. Topics include steel sourcing, forging hammer specifications, and the evaluation of material properties through testing. Enhance your knowledge with this focused assessment.