AME 2 Q4

B. Flame hardening.

Flame hardening is a simple onboard process for case hardening steel components. It involves heating the surface of the component with an oxy-acetylene flame to the austenitizing temperature, followed by rapid quenching with water or oil. This process creates a hard, wear-resistant surface layer.

Why the other answers are incorrect:

• A. Induction hardening: This process involves heating the surface using high-frequency currents, which requires specialized equipment and is not as simple as flame hardening.  
  1. Inductive Hardening | Aalberts ST

  

  www.aalberts-st.com

• C. Nitriding: This process involves diffusing nitrogen into the surface, requiring a controlled atmosphere and longer processing times. It is not a simple onboard process.  
  1. All you need to know about gas nitriding - Thermi-Lyon

  

  www.groupe-thermi-lyon.com

• D. Carburizing: This process involves diffusing carbon into the surface, requiring a controlled atmosphere and longer processing times. It is not a simple onboard process.  
  1. Effect of the Atmosphere for Heat Treatment on Carbon Flux in Ultra-Rapid Carburizing

  

  www.jstage.jst.go.jp

Flame hardening is a relatively simple process that can be performed on-board using readily available equipment, making it a suitable choice for many applications.

B. Increased hardness at the surface, while maintaining a tough core.  

1. [Solved] The process of improving the hardness of the outer layers on - Testbook

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Case hardening creates a hard, wear-resistant surface layer while preserving the toughness and ductility of the core material. This combination of properties is essential for components subjected to high wear and stress, such as gears, cams, and bearing surfaces.

Why the other answers are incorrect:

• A. Increased hardness and ductility throughout the entire component. Case hardening specifically increases hardness at the surface, not throughout the entire component. Ductility is generally maintained in the core.
• C. Decreased hardness and increased ductility throughout the entire component. Case hardening increases hardness, not decreases it. Ductility is generally maintained in the core.
• D. No significant change in the properties of the component. Case hardening significantly alters the properties of the component by creating a hard, wear-resistant surface layer.

The primary goal of case hardening is to improve the wear resistance of the component's surface while maintaining the toughness and ductility of the core.

C. To enhance the wear resistance of the component's surface.

Case hardening is primarily used to increase the hardness and wear resistance of a component's surface while maintaining the toughness of the core. This combination of properties is essential for components subjected to high wear and stress, such as gears, cams, and bearing surfaces.

Why the other answers are incorrect:

• A. To increase the overall ductility of the component. Case hardening actually improves hardness, which can decrease ductility in the hardened layer, although the core remains tough.
• B. To improve the machinability of the component. Case hardening typically makes the surface harder, which can reduce machinability. This process is focused on improving wear resistance.  
  1. What is Case Hardening? | Metal Supermarkets UK

  

  www.metalsupermarkets.co.uk

  2. The Use of Case Hardening to Improve Wear Resistance in Metal Components

  

  www.lindbergmph.com

• D. To reduce the weight of the component. Case hardening does not affect the weight of the component. Its purpose is to modify the properties of the surface.

The primary goal of case hardening is to enhance the wear resistance of the component's surface while maintaining the toughness of the core.

C. A process where the workpiece is heated in a carbon-rich environment to introduce carbon into the surface layer.  

1. An overview of heat treatment techniques | Thermal Processing Magazine

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Solid pack carburizing involves surrounding the steel component with a carbon-rich material (like charcoal) and heating it in a sealed container. The carbon diffuses into the surface of the steel, creating a hard, wear-resistant layer.

Why the other answers are incorrect:

• A. A heat treatment process where only the surface of the workpiece is rapidly heated using high-frequency currents, followed by quenching. This describes induction hardening, not solid pack carburizing.
• B. A chemical process where nitrogen is diffused into the surface of the workpiece to form a hard compound layer. This describes nitriding, not solid pack carburizing.
• D. A heat treatment process involving heating the entire workpiece to a high temperature, followed by quenching. This describes a full hardening process, not solid pack carburizing.

Solid pack carburizing specifically involves surrounding the workpiece with a carbon-rich material and heating it to allow carbon diffusion into the surface, creating a hard layer.