Date Published: 05/09/2006
Abstract:
It is well established that carburization of low alloy steels promotes compressive residual surface stress upon quenching, and that compressive surface stresses enhance fatigue life. In an effort to build upon these established facts, a US Army sponsored project is in-progress to improve helicopter gear fatigue life through innovative quenching and the achievement of deeper compressive surface stress. The Army has established a goal to improve the power density and life of helicopter transmissions. Using Pyrowear® 53 alloy steel, notched test bars and full test gears have been heat treated by carburizing, quenching, deep freezing and tempering. The quench methods examined were conventional oil quenching and intensive quenching. Bending fatigue results for these pieces will be discussed in conjunction with heat treatment finite element simulation and x-ray analysis of combined heat treatment residual and gear loading stresses.
Author: A. M. Freborg, B. L. Ferguson, Z. Li, D. X. Schwam, and B. J. Smith
Tags: bending fatigue strength, carburized aerospace gears, Pyrowear 53, residual stress measurement/validation, model validation, physical characterization, bending fatigue performance, loading model, hardness profile measurement, and single tooth bending fatigue
Process Used: carburizing, oil quench, intensive quench, deep freeze, and temper
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