Case Hardening Process Overview

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Questions and Answers

Which measuring device is commonly used for precision measurements of small dimensions?

Dial gauge

Feeler gauge

Steel rule

Micrometer (correct)

What type of tool is a surface gauge?

Cutting Tool

Measuring Device

Marking Tool

Supporting Tool (correct)

Which of the following is NOT a type of holding tool?

Surface gauge (correct)

Pin vice

C-clamp

Bench vice

Which tool would be most appropriate for measuring the angle of a surface?

Bevel protector Signup and view all the answers

What is the purpose of using a try square in fitting?

To check the squareness of a joint Signup and view all the answers

Which tool is best suited for making linear measurements with high precision?

Calipers Signup and view all the answers

Which of these is a non-precision instrument used for angular measurements?

Engineers square Signup and view all the answers

What type of tool is a profilometer used for?

Measuring surface profile Signup and view all the answers

What is the primary purpose of case hardening steel?

To extend the life of machine parts Signup and view all the answers

Which process involves heating an iron-base alloy in contact with cyanide salt?

Cyaniding Signup and view all the answers

Why is tempering performed on hardened steel?

To reduce brittleness and improve toughness Signup and view all the answers

In the spheroidization process, iron base alloys are heated to what temperature below the lower critical temperature?

20 to 40°C Signup and view all the answers

What is one of the main objectives of the spheroidization process?

To ease machining Signup and view all the answers

What is the primary use of triangular files?

Filing corners between 60° and 90° Signup and view all the answers

Which of the following is NOT a characteristic of case hardening?

It is primarily used on high-carbon steels Signup and view all the answers

At what temperature range is the tempering process typically carried out?

200°C to 450°C Signup and view all the answers

Which type of file is commonly used for finishing narrow slots?

Pillar files Signup and view all the answers

What does cyaniding primarily accomplish in the case hardening process?

Diffusion of nitrogen and carbon Signup and view all the answers

What characterizes the cutting edge of scrapers?

Hardened and tempered Signup and view all the answers

What is the composition of a chisel's body?

High carbon steel or tool steel Signup and view all the answers

For what purpose are round files primarily used?

Opening out holes and rounding inside corners Signup and view all the answers

Which type of file is described as extremely delicate and used for fine work?

Knife-edge files Signup and view all the answers

What tools are classified into flat, hook, triangular, and half round according to shape?

Scrapers Signup and view all the answers

When a chisel's cutting edge becomes blunt, what is the recommended maintenance procedure?

Sharpen it by grinding Signup and view all the answers

What is the primary characteristic of fusion welding?

Melting of both parts with possible filler metal addition Signup and view all the answers

Which of the following is an example of solid state welding?

Diffusion welding Signup and view all the answers

Which statement best describes a limitation of welded joints?

They may contain defects that are hard to identify Signup and view all the answers

What is one advantage of welding over mechanical fastening?

Welding provides a permanent joint Signup and view all the answers

What differentiates arc welding from gas welding?

Arc welding uses electrical current while gas welding uses flames Signup and view all the answers

Which process is considered a related process to welding?

Oxy-acetylene cutting Signup and view all the answers

Why is welding considered to be one of the most economical ways to join parts?

It typically reduces material waste and fabrication costs. Signup and view all the answers

What is a common risk associated with most welding operations?

Inherent dangers from high energy use Signup and view all the answers

What does 'black' refer to in the term 'blacksmithy'?

A layer of oxides on heated metal Signup and view all the answers

Which type of furnace is the least expensive and used for small to medium size stock?

Box / Batch Type Furnace Signup and view all the answers

What is defined as the controlled plastic deformation of metal into predetermined shapes?

Forging Signup and view all the answers

What is forgeability?

The ability of a material to deform under load without rupture Signup and view all the answers

In which furnace type is oxidation minimized during the heating process?

Induction Furnace Signup and view all the answers

Which of the following furnaces is primarily automated and heats materials through resistance?

Resistance Furnace Signup and view all the answers

What characterizes a rotary hearth furnace?

It rotates to ensure even heating of stock Signup and view all the answers

What is NOT a feature of heated furnace materials?

Elasticity Signup and view all the answers

Study Notes

Case Hardening Processes

Case hardening enhances surface hardness of steel by adding carbon, improving object lifespan.
Used extensively in manufacturing machine parts, carbon steel forgings, and pinions.
Also known as surface hardening, with historical applications including horseshoes and utensils.
Cyaniding involves heating iron alloys with cyanide salts for carbon and nitrogen absorption, followed by quenching.
Nitriding diffuses nitrogen into metal surfaces for case-hardening, applied to low, medium, and high-carbon steels, titanium, aluminum, and molybdenum.
Tempering is performed post-hardening to reduce brittleness by reheating steel to 200°C - 450°C, impacting toughness and hardness inversely related.

Spheroidization

A low-temperature annealing process, heating alloys 20-40°C below critical temperature for extended periods (e.g., 4 hours for 2.5 cm diameter pieces).
Objectives include reducing tensile strength, increasing ductility, easing machining, and other applications.

Tools Used in Fitting

Marking Tools: Include steel rule, prick punch, combination set, and various squares (try, flat, bevel).
Measuring Devices: Utilize gauges for fillet/radius, screw pitch, linear measurements (steel rule, calipers), and precision instruments (micrometers, Vernier gauges).
Supporting Tools: Include vee-blocks, marking tables, surface plates, and sine bars.
Holding Tools: Various vices (hand, bench, leg) and clamps (C-clamps, G-clamps) tailored for specific tasks.
Striking Tools: Different hammers (ball peen, cross-peen) for varied applications.
Cutting Tools: Hand files (flat, triangular, round), scrapers (flat, hook, triangular), and chisels made from high carbon or tool steel for cutting and chipping.

Welding Techniques

Fusion Welding: Joins parts by melting together, with processes like arc welding and oxyfuel gas welding.
Solid State Welding: Achieves coalescence through heat and/or pressure without melting the base metals, including forge and friction welding.
Welding offers a permanent joint more economically than mechanical fastening but is labor-intensive and can be hazardous.
Quality control in welded joints can be challenging, as defects are not always apparent.

Types of Welding Processes

Classification includes:
- Arc Welding (various types)
- Gas Welding (oxy-acetylene, oxy-hydrogen)
- Thermit Welding
- Solid State Welding (friction, ultrasonic)
- Newer methodologies (laser, electron-beam)

Forging

Defined as the controlled plastic deformation of metal into predetermined shapes.
"Forgeability" indicates a material's ability to deform without rupture.
Affected by grain structure, which contributes to strength and toughness; often requires additional heat treatment.

Heating Devices and Furnaces

Furnaces include:
- Box/Batch Type Furnace: Economical for small/medium stocks, insulated with refractory materials.
- Rotary Hearth Furnace: Doughnut-shaped, uses gas or oil, rotates stock for uniform heating.
- Continuous/Conveyor Furnace: Feeds larger workpieces through a narrow furnace for consistent heating.
- Induction Furnace: Uses induction coils to heat stocks, reducing oxidation and scale formation.
- Resistance Furnace: Quick and often automated, heats stock through electrical resistance in a circuit.

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Description

This quiz explores the case hardening process, focusing on the use of carbon compounds to enhance steel durability. Learn about the applications of case hardened steel in machine parts, forgings, and pinions. Understanding this technique is crucial for improving the lifespan of various industrial components.