Question

The cutting tool manufactured by powder metallurgy is

• A. High speed steel
• B. High carbon steel
• C. Low carbon steel
• D. Sintered carbides

Hint:

Powder metallurgy is a critical manufacturing route for materials that are difficult to process by conventional means, or for creating composite materials with unique properties. Sintered carbides (also known as cemented carbides) are a prime example, offering exceptional hardness and wear resistance for cutting tools, and their production relies heavily on powder metallurgy.

Answer 1

The Correct Option is D

Step 1: Understand powder metallurgy.
Powder metallurgy (PM) is a manufacturing technique consisting of three main steps: powder production, powder compaction, and sintering. It's used to create parts from metal powders. This process is particularly useful for materials with high melting points, those that are brittle, or for creating composite materials with unique properties.
Step 2: Evaluate the options in the context of powder metallurgy for cutting tools.
Cutting tools require high hardness, wear resistance, and hot hardness (ability to retain hardness at high temperatures). (1) High speed steel (HSS): HSS tools are typically manufactured by conventional methods like casting and forging, followed by machining and heat treatment. While some specialized HSS powders exist for tool manufacturing (e.g., for near-net shape or improved microstructure), it's not the primary or most common cutting tool material produced by powder metallurgy in the general context compared to sintered carbides. (2) High carbon steel: High carbon steels are used for tools but are generally not produced by powder metallurgy for cutting applications due to their lower hardness and hot hardness compared to other tool materials. They are usually shaped by forging and machining. (3) Low carbon steel: Low carbon steels are soft and ductile and are used for structural components, not for cutting tools, regardless of the manufacturing process. (4) Sintered carbides (Cemented Carbides): These are composite materials primarily composed of hard carbide particles (e.g., tungsten carbide, titanium carbide, tantalum carbide) bonded together by a metallic binder (most commonly cobalt). Sintered carbides are almost exclusively manufactured by powder metallurgy. The powders of the carbide and binder are mixed, compacted into a desired shape, and then sintered at high temperatures. This process results in extremely hard and wear-resistant cutting tools with excellent hot hardness, making them ideal for machining hard materials at high speeds.
Step 3: Conclude the best fit.
Sintered carbides are the most prominent and suitable cutting tool material manufactured using powder metallurgy due to their superior hardness and wear resistance. The final answer is $\boxed{\text{4}}$.