Quenching technology: a selected overview of the current state-of-the-art

Abstract

Many papers have been published on a wide range of aspects of the fundamental physics and chemistry of quenching such as: additive technology, surface rewetting, hardness distribution prediction, role of heat transfer and residual stresses, etc.1,2. However, relatively little information has been published on the application of these insightful research results for the solution of long standing quench tank production problems. This paper will address three areas where technical advancements have been, or may be, made. These include discussion of: 1) the application fundamental fluid dynamics to characterize quenching uniformity due to agitation; 2) the use of "waves" to provide uniform agitation during the quenching process; and 3) the use of pressure as a variable to mediate heat transfer throughout the quenching process

Numerical simulation of immersion quenching process of an engine cylinder head

“…From the differentiating results at various monitoring locations, we conclude that our model has been able to accommodate the quench rate fluctuations introduced by variations in the dipping orientation [3][4][5], although some inconsistencies remain in modeling their dynamics in the numerical model. Particularly, detailed physical effects of orientation of the quenching surface, surface roughness, bubble nucleation on the heat flux modification [7] have not been taken into consideration in the current form of the model.…”

“…However, it is to be noted that transient heat flux is significantly fluctuating in comparison to the steady state heat flux [3,[34][35][36] …”

“…This is motivated by the fact that the Al-alloys have very good mechanical properties combined with high strength-to-weight ratio, which can reduce the overall vehicle weight and, henceforth, improve the fuel efficiency. Heat treatment process is one of the important methods for improving the mechanical properties of the aluminum alloys, which in this context can gravely influence the functionalities of the final product design [2][3][4][5]. The necessary specification concerning the strength of the alloy are commonly met by precipitation hardening, which involves a specific heat treatment process followed by an aging treatment at an specified intermediate temperature [2,6].…”

“…Following the immersion of the metallic object into the quenchant (water), variable heat transfer mechanisms are dictated based on the initial temperature of the dipped solid. In the event that the dipped metal temperature is higher than the Leidenfrost limit, a vapor blanket is placed around the metal object initiating a film boiling mode [3][4][5][6][7]. The heat transfer from the metal to the surroundings is very slow since it occurs by a pure conduction process across the vapor film [4,7].…”

“…The heat transfer coefficient in the nucleate boiling regime representing the regimes containing periodic dry patches, vapor columns and discrete bubble systems along with the effects of natural convection are neglected. This approximation is held valid since the predominant cooling during the quenching process occurs in the transition boiling regime and the contribution of nucleate boiling and natural convection takes effect only when the wall superheat is of the order of 30-40 K[3][4][5].…”