THE TENSION TEST is one of the most commonly used tests for evaluating materials. The material characteristics obtained from tension tests are used for quality control in production, for ranking performance of structural materials, for evaluation of alloys, and for dealing with the static-strength requirements of design. This article describes the stress-strain behavior during a tension test and provides the definition of terms such as stress, force, strain, and elongation. It explains the tensile properties obtained from the test results: the tensile strength and yield strength, which includes offset yield strength, extension-under-load yield strength, and upper yield strength. The article concludes with a description of the general procedures for conducting the tension test based on ASTM standards and the variability of tensile properties.

Dual-phase steels are a new class of high-strength low alloy (HSLA) steels characterized by a microstructure consisting of about 20% hard martensite particles dispersed in a soft ductile ferrite matrix. In addition to high tensile strength, in the range of 550 MPa (80 ksi), dual-phase steels exhibit continuous yielding behavior, a low 0.2% offset yield strength, and a higher total elongation than other HSLA steels of similar strength. The article discusses some of the more pertinent aspects of dual-phase steels, such as heat treatment, microstructure, mechanical properties, chemical composition, and manufacturability. In general, these steels have a carbon content of less than 0.1%, which ensures that they can be spot welded. However, newer high-carbon dual-phase steels in development are generating interest due to their unique combination of total elongation and tensile strength.