When selecting a material for a particular application, engineers must be confident that it will be suitable for the loading conditions and environment it will experience in service. An understanding of the properties of materials is therefore essential. The mechanical properties of steel can be carefully controlled through the selection of an appropriate chemical composition, processing and heat treatment, which lead to its final microstructure.
In this module you will learn about the mechanical properties of steels, their selection for specific applications and the standards and specifications for several important markets. You will also be able to carry out sampling and preparation of test pieces for evaluation by virtual hardness, tensile and Charpy impact tests. These tests can be run as standalone tests or as a complete ‘sample and test’ exercise.
Since it is important that a component can actually be manufactured, this module also contains a section on formability and the use of Forming Limit Diagrams (FLD) to predict which combinations of strains and material thickness will result in failure.
Learning Outcomes for this Section
After completing this section, you should be able to:
- Describe why steel standards have been established and identify some commonly used specifications
- Identify in detail the requirements of the American Bureau of Shipping Standard
- State how much steel was produced in the world in 2004
- Identify where and how to take samples from a steel plate to carry out mechanical property tests to determine whether it meets the above standard
- Describe how hardness is tested and explain the differences between the three most common tests
- Describe how a tensile test is carried out and explain the differences between engineering and true stress/strain
- Describe a Charpy impact test is carried out and how the Ductile-Brittle Transition Temperature (DBTT) is calculated
- Identify and explain the differences between brittle and ductile fracture surfaces
- Carry out virtual hardness, tensile and Charpy impact tests
- Describe appropriate measure of formability for deep drawing and stretch-forming
- Explain how Forming Limit Diagrams can be used to predict which combination of strain/material thickness will result in failure
Pre-Requisites
Before starting, it is important that you are familiar with the following terms: Yield stress; Stress; Strain; Strength; Ductility; Toughness;
Authors/Contributors:
- Robert Cochrane, Consultant