Transformation-induced plasticity (TRIP) steels are characterized by their excellent strength and high ductility, which allow the production of more complicated parts for lightweight automotive applications. This chapter provides an overview of the compositions, microstructures, processing, deformation mechanism, mechanical properties, hot forming, tempering, and special attributes of TRIP the steels.

This chapter briefly discusses the characteristics of mechanical twins and stacking faults in close-packed planes. It provides an overview of the composition, microstructures, thermodynamics, processing, deformation mechanism, mechanical properties, formability, and special attributes of twinning-induced plasticity steels.

Plastic gears are continuing to displace metal gears in applications ranging from automotive components to office automation equipment. This chapter discusses the characteristics, classification, advantages, and disadvantages of plastics for gear applications. It provides a comparison between the properties of metals and plastics for designing gears. The chapter reviews some of the commonly used plastic materials for gear applications including thermoplastic and thermoset gear materials. The chapter also describes the processes involved in plastic gear manufacturing.

This chapter describes the molecular structures and chemical reactions associated with the production of thermoset and thermoplastic components. It compares and contrasts the mechanical properties of engineering plastics with those of metals, and explains how fillers and reinforcements affect impact and tensile strength, shrinkage, thermal expansion, and thermal conductivity. It examines the relationship between tensile modulus and temperature, provides thermal property data for selected plastics, and discusses the effect of chemical exposure, operating temperature, and residual stress. The chapter also includes a section on the uses of thermoplastic and thermosetting resins and provides information on fabrication processes and fastening and joining methods.

The key to any successful part development is the proper choice of material, process, and design matched to the part performance requirements. This article presents examples of reliable material performance indicators and common practices to avoid. Simple tools and techniques for predicting plastic part performance (stiffness, strength/impact, creep/stress relaxation, and fatigue) integrated with manufacturing concerns (flow length and cycle time) are demonstrated for design and material selection.