This paper examines the causes of distortion in heat treated 1080 steel parts and the influence of quenchants and quenching temperature. A comparison of parts produced using a different oil and different quench temperatures shows that a significant improvement can be achieved in distortion with only minor grain growth and a slight reduction in hardness.

A number of modifications were made to a batch quenching process for pinion gears to reduce the amount of size change in the ID. This paper assesses the impact of adding vertical plates to the load elevator to better condition oil flow to the stacked part baskets. Data collected from pinion gears before and after the modification show a reduction in the average and range of ID bore change, indicating an improvement in quench uniformity. CFD analyses suggest that improvement is due to a significant reduction in turbulence, resulting from the addition of the vertical plates. As the authors explain, high levels of turbulence promote collapse of the vapor film that occurs at the start of the quench process, and disparity in the timing causes unwanted variation in part size change throughout the load.

This paper presents a computational approach for assessing the potential for distortion when using high pressure gas to quench steel parts. It explains how to account for component geometry, heat transfer coefficient, gas temperature and velocity, heating and cooling rates, and phase transformations. The authors employ finite element modeling methods to determine local phase fraction and displacement in a Ferrium C64 disk for different quench pressures. Simulations at timed intervals show how distortion and phase fraction progress in different areas of the disk and along the edges of an off-center bore. The causes of distortion are examined and explained using the model, with insights into why the cooling rate has a nonlinear relation with distortion.

Press quenching is often used to harden parts that are sensitive to distortion, but it is a difficult process to control due to the effects of tooling and the relatively large number of process parameters. In this paper, the authors show how they use finite element analysis to optimize the process and tooling design for a spiral bevel gear made of carburized 9310 steel. Several designs adaptations are assessed, one of which is shown to minimize radial shrinkage and taper distortion in the inner diameter of the bore.

This paper describes the inner workings of a gas quenching chamber and assesses its potential for high-volume production of precision gears. The cooling manifold in the chamber surrounds the part, which sits on a rotating table. This ensures uniform flow of cooling gas across the top, bottom, and sides of the part and achieves uniform and repeatable quenching results. In addition, because the cooling nozzles can be adjusted to fit the geometry and size of the part, distortion can be effectively controlled.

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.

Although many have had success using CFD and FEA techniques to predict residual stress and distortion in water quenched aluminum alloys, there are still hurdles in using a computational approach to manage liquid quenching processes due to the lack of a quench severity database. Quench severity is defined by the Grossman number, which does not serve as a heat transfer model for CFD simulation because it omits much of the underlying physics. In this research, a new interpretation of quench severity makes it possible to separate the heat transfer model into two groups, one computable by CFD and one requiring calibration. The objective of this paper is to parameterize the boiling model by quenching conditions and validate the model using data obtained by quenchometer testing.

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.

Samples from forged and heat-treated steel products with known quench crack histories have been mapped in order to study a possible relation between banding segregation and quench cracking. The products were medium carbon low alloy steels produced by ingot and continuous casting. EDS X-ray mapping was used to characterize the banding pattern and tensile testing revealed corresponding properties. The experimental procedures are described in the paper along with test results and conclusions.

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.