Effect of Quenching Parameters on Distortion Phenomena in AISI 4340 Steel

Abstract

During quenching heat treatment, the formation of high residual stress values and the presence of distortion are phenomena which are difficult to control and accurately predict, their effects being extremely important to the components or pieces of complex and robust geometry that are commonly used in the industry. The latter is mainly due to the mixture of the high temperature levels formed between the surface and the cores of the components and the martensitic transformation during quenching. In this research, an experimental and simulated analysis of the process of the quenching heat treatment of AISI 4340 steel, using geometrically complex components, was undertaken with the objective of studying and understanding the effect of quenching process parameters on distortion, stress generation, and mechanical properties. A model that applied the finite elements method (FEM), in which entry data such as thermo-physical and mechanical properties were obtained through experimental techniques that were reported in the literature, made it possible to simulate the cooling process under different conditions, which helped to explain the origins of the distortion in the quenched parts. The results show a close relationship between various quenching parameters such as heat extraction speed, the immersion orientation in the liquid, and the component’s geometry. The data obtained could contribute to accelerating the design process of the heat processing routes for quenching components by taking into consideration both the classic process variables and, due to the increased precision resulting from mathematical modeling, additional factors such as the geometry of real applications.

Study of Cooling Medium Variables during Quenching in SAE 4340 Steel Using Statistical and Modeling Tools

“…The computed domain of geometry is shown in Figure 2 and the conditions of the simulation processes are shown in Table 2. A precise description of the heat transfer and phase transformation models used in this study are published in the former work of Lopez-Garcia et al [26]. To evaluate the distortion, the measurements of the dimensions of the Navy C-rings before and after the quenching heat treatment were carried out using Mitutoyo Absolut Digimatic 500-197-30 equipment with a 0.01 mm resolution.…”

“…The computed domain of geometry is shown in Figure 2 and the conditions of the simulation processes are shown in Table 2. A precise description of the heat transfer and phase transformation models used in this study are published in the former work of Lopez-Garcia et al [26]. Temperature dependent, see Figure 3 The simulation variants to reproduce the experimental quenching conditions were two different quenching media temperature (27 and 60 • C), and two different HTC as follow: the 100 L/min oil flux case was calculated by the inverse method using the experimental cooling curves, the details of which will be addressed in an unpublished work in progress by the authors.…”

“…They found that the greatest hardness is achieved with agitation at a temperature of 45 • C in a liquid environment using Na 2 SO 4 and NaNO 2 as the cooling medium. Lopez-Garcia et al [26] analyzed the dimensional behavior and residual stresses of a complex piece of AISI 4340 steel, modifying some variables of the quenching heat treatment, such as the immersion position and quenching medium. They used finite element modeling to compare experimental and simulated results, in addition to optical microscopy and distortion measurement.…”

“…In recent years, many investigations have been carried out on the phenomena of distortion and residual stress in metallic components, mainly in processes that require high-dimensional precision, such as welding, machining, and quenching heat treatment, using finite element methods (FEM). The results obtained have contributed significantly to reducing productivity losses in manufacturing industries and increasing production processes [26,[31][32][33][34][35][36]. Cho et al [37] employed FEM to evaluate the effect of quenching heat treatment on distortion for bevel gears in machined and forged SAE 4118H steel.…”

Numerical Model of Simultaneous Multi-Regime Boiling Quenching of Metals

“…Stresses generated from this lagging may cause deformation or even cracks. Optimal immersion routes should be considered when quenching workpieces [29,30], and they may be related to this multi-regime boiling phenomenon.…”