The knowledge of the thermal boundary conditions helps to understand the heat transfer phenomena that takes place during heat treatment processes. Heat Transfer Coefficients (HTC) describe the heat exchange between the surface of an object and the surrounding medium. The Fireworks Algorithm (FWA) method was used on near-surface temperature-time cooling curve data obtained with the so-called Tensi multithermocouple 12.5 mm diameter x 45 mm Inconel 600 probe. The fitness function to be minimized by a Fireworks Algorithm (FWA) approach is defined by the deviation of the measured and calculated cooling curves. The FWA algorithm was parallelized and implemented on a Graphics Processing Unit architecture. This paper describes the FWA methodology used to compare and differentiate the potential quenching properties of a series of vegetable oils, including cottonseed, peanut, canola, coconut, palm, sunflower, corn, and soybean oil, versus a typical accelerated petroleum oil quenchant.

Many alternative ecofriendly quenchants have been developed to replace mineral oil such as vegetable oils, polymer quenchants, and nanofluids. Although vegetable oils show superior cooling performance to mineral oil, their use is limited due to high production costs and low thermal stability. In this study, used coconut oil was chemically treated and its cooling and heat transfer characteristics were compared with that of refined coconut oil and mineral oil. The thermophysical properties of chemically treated waste coconut oil were found to be higher than that of the other oils tested, and its wettability proved to be better as well. Quenching experiments using an Inconel 600 probe (as per ISO 9950 and ASTM D 6200 standards) showed that the vapor blanket stage was shorter for the chemically treated oil than either of the others. The treated waste oil was also found to have the highest average peak heat flux based on the solution to the inverse heat conduction problem.

Excessive distortion was observed in many small components made from 1080 steel that was neutral hardened following stamping. A study was then undertaken to determine how to reduce the distortion of the heat-treated parts while maintaining proper hardness and microstructure. A numerical simulation based on Simheat software was conducted to determine the effect of elevated temperature on the quenching oil used and its impact on distortion and microstructure. A second oil designed to operate at higher temperatures was also examined. Using Simheat software, the two oils were compared based on predicted distortion, hardness, and microstructure and the results were subsequently validated using empirical methods. It was concluded that a significant improvement in distortion could be achieved by using a different oil and higher quench temperatures.

This work investigates the cooling performance of different salt solutions and quench bath parameters. The results show that increasing quenchant temperature can stabilize the vapor film, while the presence of various additives and the use of agitation can hasten its collapse. Ionic solutions containing NaCl, Na2SO4, NaOH, and NaNO2 were found to inhibit the vapor blanket at 35°C and improve cooling power. Adding salt-forming solutions promoted a more homogeneous cooling with high values of heat flux over most of the cooling cycle.

In various studies, heat transfer coefficients (HTCs) have been used to characterize the relative ability of a quenching medium to harden steel. In this current work, HTCs are determined for a series of vegetable oils using a stochastic (particle swarm) optimization technique and cooling curves produced via Tensi probe measurements. The vegetable oils investigated include canola, coconut, corn, cottonseed, palm, peanut, soybean, and sunflower oil, and their quenching performance is compared with that of a typical petroleum oil quenchant.

In this investigation, the authors use a Tensi probe to obtain cooling curves for canola and palm oils and determine their heat transfer coefficient profiles. For comparison, the cooling curve of an accelerated petroleum oil quenchant is also presented. Canola oil exhibited minimal evidence of film boiling, while palm oil showed a pronounced film boiling behavior. This behavior suggests the presence of unrefined volatile by-products or subsequent degradation. The petroleum quenchant exhibited wetting front movement along the Tensi probe not observed with the vegetable oils.

A variety of test systems have been developed to determine the cooling characteristics of quenchants. Although current test standards specify cylindrical probes for measuring quenchant temperatures and cooling rates, this review concerns the development, implementation, and potential of test systems that use ball probes instead. It assesses the strengths and limitations of different types of ball probes and describes prototype test systems that leverage ball probe capabilities while compensating for inherent weaknesses.

Quench oil is susceptible to contamination from carbon deposits, dirt, water, and the byproducts of oxidation. This paper discusses the causes of contamination in quench oil and explains how they lead to reduced oil life, sludge accumulation, loss of production time, unplanned maintenance, variations in the quench curve, surface deposits, and rework costs associated with additional part cleaning. It describes the differences between parts quenched in clean and dirty oil and presents best practices for keeping quench oil clean by removing particulate and water over the course of its life.

In order to use quench oils over extended periods of time, it is necessary to understand how their properties and performance respond to heat and oxidation. This study investigates the effect of thermal and oxidative deterioration on dark and transparent quench oils. It describes the performance and property changes observed using accelerated testing methods and explains how quench oil behaviors in a laboratory setting compare with actual quench furnace usage.

This paper presents the results of a study on the cooling performance of hot oil and molten salt quench media. It describes the tests performed, analyzes the results, and interprets the findings. It explains how the heat extraction mechanism in hot oil differs from that of NaNO2 eutectic mixtures and how it translates to differences in cooling rate, spatial uniformity, and hardness in quenched steel parts.