Gustavo Sánchez Sarmiento

Simulation Of Heat Transfer Properties And Residual Stress Analyses Of Cooling Curves Obtained From Quenching Studies

This paper describes the use of computational simulation to examine the heat transfer properties and resulting residual stress obtained by quenching a standard probe into various quench oils. Cooling curves (timetemperature profiles) were obtained after immersing a preheated 12.5 mm dia. X 60 mm cylindrical Inconel 600 (Wolfson) probe with a Type K thermocouple inserted into the geometric center into a mineral oil quenchant. Different quenching conditions were used, as received (“fresh”) and after oxidation. Surface temperatures at the cooling metal – liquid quenchant interface and heat transfer coefficients are calculated using HT-Mod, a recently released computational code. Using this data, the temperature distribution was calculated. The corresponding distortion and residual stresses were calculated using ABAQUS. This work illustrates potential benefits of computational simulation to examine the expected impact of different quenchants and quenching conditions on a heat treatment process.

Water and Polymer Quenching of Aluminum Alloys: A Review of the Effect of Surface Condition, Water Temperature, and Polymer Quenchant Concentration on the Yield Strength of 7075-T6 Aluminum Plate

Cold water is perhaps the most common quenchant used for heat treatable aluminum alloys. In many situations, excessive distortion and cracking problems require the use of a less severe quenchant such as hot water or a Type I aqueous polymer quenchant. However, when these alternative quenching media are used, the distortion improvement achieved is typically accompanied by a corresponding loss of strength. This paper will provide an overview of cold versus hot water quenching and the potential use of Type I polymer quenchants. The potential use of quench factor analysis to aid in quenchant media selection and corresponding property prediction is reviewed and applications are demonstrated. The often dramatic impact of the surface condition of aluminum on quenching performance and properties achieved will also be included in this review.

Effect of drying conditions on the quality of IRGA 424 rice: Effects of drying on rice quality

BACKROUND The objective of this research was to investigate the effects of drying temperature (40, 50, and 60 °C), tempering time (40, 80, and 120 min), and initial moisture content at onset of tempering (15, 17, and 19% dry basis) on head rice yield, milled rice yield, and total processing time of IRGA 424 rice. RESULTS The most significant effects were the drying temperature and its interaction with initial moisture content at onset of tempering. The optimum conditions predicted to reach the highest total yield (74.1%) included drying at 46.6 °C, 49 min of tempering time, and initial moisture content at onset of tempering of 19%. To achieve the maximum value of whole grain yield (52.9%), drying at 40 °C, 40 min of tempering, and an initial moisture content of 19% at the initiation of tempering were required. Under these conditions, the grain reached a moisture content of 13% in 84 min. CONCLUSION Whole-grain rice yields may be maximized through the optimization of the drying process. This may result in a larger fraction of the crop entering the human food chain, enhancing the value of the crop, and resulting in a smaller fraction of broken grain, which commands a lower market value.