This appendix discusses the sizing, scaling, and configuration requirements of the basic components in a quench cooling system, including tanks, pumps, hoses, and inlet and outlet fixtures and the materials from which they are made.

The decomposition of austenite, during controlled cooling or quenching, produces a wide variety of microstructures in response to such factors as steel composition, temperature of transformation, and cooling rate. This chapter provides a detailed discussion on the isothermal transformation and continuous cooling transformation diagrams that characterize the conditions that produce the various microstructures. It discusses the mechanism and process variables of quenching of steel, explaining the factors involved in the mechanism of quenching. In addition, the chapter provides information on the causes and characteristics of residual stresses, distortion, and quench cracking of steel.

This chapter examines the cooling of steels from the austenite region. It describes the processes of determining the severity of quench. The chapter examines the methods to estimate the quench required if the size and shape of the part are known and the required cooling rate is known. The cooling rate correlation is used to calculate the hardness distribution across the diameter of cylinders. The calculations are used to illustrate the sensitivity of the hardness distribution to the severity of quench and the hardenability. The chapter discusses the methods of determining cooling rates in quenched steel components. It describes the formation of residual stresses in materials in which no phase change occurs on cooling. The chapter also examines the effect on the residual stresses of the phase changes in austenite. It provides information on two types of quench cracks in quenched steels, namely, microcracking and gross cracking during quenching.

The hardenability of steel is governed almost entirely by the chemical composition (carbon and alloy content) at the austenitizing temperature and the austenite grain size at the moment of quenching. This article introduces the methods to evaluate hardenability and the factors that influence steel hardenability and selection. The discussion covers processes involved in Jominy end-quench test for evaluating hardenability. The effect of carbon on hardenability data and the effect of alloys on hardenability during quenching and on the tempering response (after hardening) are also discussed. In addition, the article provides information on the hardenability limits of H-steels after a note on hardenability correlation curves and Jominy equivalence charts.