Untitled Quiz

Steel and Definition

• Steel is a metal alloy primarily composed of iron and carbon, often containing small amounts of manganese, phosphorus, sulfur, and silicon.

Metal Grades and Classification

• Grades refer to numerical designations that describe the content of metal alloys.
• Classification of metals helps to understand their specific properties and behaviors.

Factors Influencing Metal Properties

• The behavior and properties of metals are determined by:
  • Chemical composition: The atomic-level makeup of the material.
  • Heat treatment: A process of heating and cooling to change the metal's structure and properties.

Steel Composition

• All steel contains primarily iron and carbon.
• Alloy steel contains additional materials intentionally added to enhance specific properties.

Steel Production Process

• Electric arc furnaces utilize electric arcs between electrodes to transform pig iron and other materials into steel.

Organizations and Classification Systems

• The American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE) created the classifications for steel.
• AISI-SAE designations use a three- or four-number code to indicate the percentages of a steel's components.
• The Unified Numbering System (UNS) employs five numbers for classification and is not limited to steel.

Types of Carbon Steel

• Plain carbon steels contain less than 3% of elements other than iron and carbon, making them the most "pure" form.
• Carbon steels account for more than 75% of manufactured steel, with three main groups:
  • Low-carbon steels: Contain less than 0.3% carbon.
  • Medium-carbon steels: Contain between 0.3% and 0.5% carbon.
  • High-carbon steels: Contain more than 0.5% carbon.

Carbon Steel Series

• Four series define different carbon steels:
  • 10XX: No added elements.
  • 11XX: Extra sulfur.
  • 12XX: Extra sulfur and phosphorus.
  • 15XX: Contains manganese in the range of 1.00-1.65%.

Steel Designations

• "E": Stands for steels produced in an electric arc furnace.
• "H": Indicates special hardenability properties of the metal.
• "B": Indicates the presence of boron.
• "L": Indicates the presence of lead.

Specialized Steel Types

• Stainless steels are characterized by more than 15% chromium and excellent corrosion resistance.
• Tool steels are designed for high wear resistance, toughness, and strength.

Additional Metal Types

• Chromium is used in ferrous alloys to enhance hardness and wear resistance; stainless steels contain significant amounts of chromium.
• Nonferrous metals are classified using the UNS and do not intentionally contain iron.