Call number: LD2668 .T4 1952 P64 / Master of Science

No description available.

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1910. / The entire thesis text is included in file. Typescript. Illustrated by authors. Sidney S. Schmidt received a Bachelor of Science in General Science. Russell B. Caples received a Bachelor of Science in Mining Engineering. Both degrees determined from "1874-1999 MSM-UMR Alumni Directory". Title from title screen of thesis/dissertation PDF file (viewed March 17, 2009) Includes bibliographical references (p. 2, 17-18).

No description available.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: rust formation; AISI 8620 steel; gas carburizing. Includes bibliographical references (leaves 39-40).

"The effects of rust on the carburization behavior of AISI 8620 steel have been experimentally investigated. AISI 8620 steel samples were subjected to a humid environment for time of 1 day to 30 days. After the exposure, a part of the samples was cleaned by acid cleaning. Both cleaned and non-cleaned samples have been carburized, followed by quenching in mineral oil, and then tempered. To determine the effect of rust on gas carburizing, weight gained by the parts and the surface hardness were measured. Surface carbon concentration was also measured using mass spectrometry. Carbon flux and mass transfer coefficient have been calculated. The results show that acid cleaning removes the rust layer effectively. Acid cleaned samples displayed the same response to carburization as clean parts. Rusted parts had a lower carbon uptake as well as lower surface carbon concentration. The surface hardness (Rc) did not show a significant difference between the heavily rusted sample and clean sample. It has been observed that the carbon flux and mass transfer coefficient are smaller due to rust layer for the heavily rusted samples. These results are discussed in terms of the effects of carbon mass transfer on the steel surface and the resulting mass transfer coefficient."

This work deals with the assessment of the influence of low-temperature treatment on the structure and properties of casehardened surface layer of parts. The objective was to assess whether low-temperature treatment is sufficient, insufficient, or unnecessary for the given purpose. Gears which form a part of Zetor tractors gear boxes were used as samples. Thirteen pairs of frozen and non-frozen samples were used; they were taken from production batches throughout 2007, their hardness was assessed and furthermore, the experiment itself, freezing casehardened and hardened samples to different temperatures reaching as low as -196°C, was carried out. A moderate increase in hardness was registered with the majority of the frozen samples, which proved the effectiveness of the low-temperature treatment.

The carburizing atmosphere during the case hardening process contains a large proportion of hydrogen. Due to the rapid diffusion of hydrogen a high amount of hydrogen can be absorbed by the carburizing component. The amount of absorbed hydrogen is dependent on some factors such as for example the carburizing time and component dimensions. Hydrogen diffused in material can then cause hydrogen embrittlement and in some cases cause cracking under a static load. This hydrogen must therefore be removed. High amounts of hydrogen diffuse out spontaneously at room temperature. Tempering accelerates the process. The aim of this study was to experimentally measure the amount of absorbed hydrogen after case hardening and hydrogen content after storage at room temperature and also after tempering. The effect of the enriching gas in carburizing furnace on hydrogen absorption was investigated in this study. Three steel grades with different content of alloying elements were used in this investigation. Steel samples were case hardened by gas carburizing and tempering. The hydrogen content analyses included the measurement of hydrogen content before case hardening, after case hardening and after tempering using Leco-RHEN602. Based on the results in this study it was concluded that all steel grades used in this investigation absorb hydrogen during case hardening by gas carburizing. A major part of the absorbed hydrogen is then released by effusion after being stored at room temperature and during tempering. Around 50% of the absorbed hydrogen content during gas carburizing is due to the presence of the enriching gas in the carburizing atmosphere. Around 50 % of hydrogen diffuses out of the steel specimens after one day. It is likely that all of free diffusible) hydrogen has diffused out of the specimens of two steel grades after one week at room temperature or after tempering. / Vid sätthärdning består den uppkolande atmosfären till stor del av vätgas och p.g.a. vätets snabba diffusion kan stora mängder av väte absorberas i komponenten. Halten av absorberade väte beror bl.a. på sätthärdningstid och komponentens dimensioner. Väte i materialet kan sedan leda till sprickbildning vid statisk belastning. Detta väte måste därför avlägsnas. En stor del av väte diffunderar ut spontant vid rumstemperatur. Vid anlöpning går processen fortare. Syftet med denna studie var att experimentellt mäta halten av väte som absorberas under sätthärdning, samt efter att metallen har lagrats i luft vid rumstemperatur. Dessutom mättes vätehalten efter anlöpning. Dessutom undersöktes effekten av ugnsatmosfärens tillsatsgas på mängden absorberad väte efter uppkolning. Tre olika höghållfasta och låg legerade stål sorter sätthärdades genom gas uppkolning. Mängden väte analyserades innan sätthärdning, efter sätthärdning, efter lagring i rumstemperatur och efter anlöpning med hjälp av Leco-RHEN602. Enligt resultaten i denna studie, absorberar alla av de tre undersökta stålsorterna väte under sätthärdning. En stor del av det absorberade vätet diffunderar ut efter att stålet har lagrats i luft vid rumstemperatur och under anlöpning. Omkring 50 % av den absorberade vätehalten under uppkolningen är på grund av reaktionen med tillsatsgasen i ugnsatmosfären. Omkring 50 % av vätet diffunderar ut ur proverna efter en dag. Möjligen all fritt (diffunderbart) väte har diffunderat ut ur proverna i två av stålsorterna efter en vecka i rumstemperatur eller efter anlöpning.

Heat treatment is the process of heating metal without allowing it to reach a molten state or melting, it and then cooling it in a controlled manner to choose desired mechanical qualities. Heat treatment aims to make the metal stronger, more malleable, more abrasion resistant, and more ductile. There is a broad range of heat treatment services such as Case Hardening, LowPressure Carburization, Vacuum Hardening, Nitriding, Tempering, and Brazing. This study aims to estimate the time used for each process in the industry to make an idea of the workers involved in the organization. This study which was conducted in the conventional case hardening method proves that the specific program B3 to that particular material (SS2511) took a total standard time of 244.98 minutes for human efforts.

Denna rapport behandlar restspänning i stålet 16MnCrS5 som uppkommer efter sätthärdning med traditionell uppkolning med släckning i olja och lågtrycksuppkolning med släckning i gas. Rapporten har ett fokus på restspänningar men behandlar även materialegenskaper generellt. I rapporten utförs en karaktärisering av materialet där författarna tittar på, kolhalt, kolprofil, ythårdhet (Rockwell C), kärnhårdhet (Vickers10kg) och hårdhetsprofil (Vickers 1kg) samt analys av mikrostruktur. Även resultat för FWHM kommer tas upp som visat sig kunna relateras till hårdheten hos materialet. Diskussionen handlar om att förklara restspänningen i materialet med hjälp av resultatet från karaktäriseringen. Lågtrycksuppkolning har visat sig inte ge inre oxidation vid sätthärdning, medan provbitar som sätthärdats med traditionell sätthärdning har uppvisat inre oxidation. Den inre oxidationen kan bidra till tryckrestspänningar vid ytan på materialet. Hög andel restaustenit har generellt visat sig vara en bidragande faktor till dragrestspänningar främst vid ytan men även inne i sätthärdningsskiktet. Resultatet har också visat att prover som värmebehandlats med lågtrycksuppkolning och har hög halt restaustenit vid ytan kan också ha hög nivå av dragrestspänning vid ytan. / This report addresses residual stress in the steel 16MnCrS5 that occurs after carburization with traditional carburization with quenching in oil and low-pressure carburization with quenching in gas. The report focuses on residual stresses but also deals with material properties in general. The report characterizes the material by looking at the, carbon content, carbon profile, surface hardness (Rockwell C), core hardness (Vickers10kg) and hardness profile (Vickers 1kg) as well as analysis of the microstructure. Low pressure carburization has been shown not to produce internal oxidation, but samples heat treated with traditional carburization has exhibited internal oxidation. High proportion of residual austenite has also been shown to be a contributing factor to tensile residual stresses, mainly at the surface but also within the curing layer. The result have also shown that residual austenite at the surface have been associated with high levels of tensile residual stress at the surface.