Tag Archives: fatigue

Axial and Bending Fatigue Performance of Shallow-Carburized SAE 8615 Steel

The previous blog examined the performance of SAE 8615 simulated-carburized steel in monotonic tensile tests and compared its performance in axial and bending fatigue conditions. This blog will explore the performance of SAE 8615 steel with a shallow-carburized case depth … Continue reading

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Fatigue Properties of Modified Steels Carburized at High Temperatures

The objective of phase XI is to compare the performance of carburized steel in bending and axial fatigue loading conditions. Carburization is a surface heat treatment process which adds carbon to the surface of a material to increase its hardness … Continue reading

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Neuber Stress Plots

This article explains how a “Neuber Stress” is calculated from fatigue test data obtained from un-notched axially-loaded specimen. In the presence of a geometric stress concentration feature on a part, the fatigue life of that part is often under-predicted as … Continue reading

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Mechanical Properties versus Carburization Depth

In this article we will examine the relationship between ultimate tensile strength, fatigue strength, and elongation versus the depth of carburization. The data for this comparison was taken from several iterations discussed in previous articles and shown in Table 1. … Continue reading

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The Effect of Bainite on Strength and Fatigue in Through-Carburized SAE 8620 Test Bars

A case microstructure may consist of martensite, retained austenite and bainite, and depends upon alloy and cooling rate. The impact of bainite on fatigue is not well known.  Sometimes carburized parts are intentionally austempered to increase the amount of bainite … Continue reading

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2017 Bar Fatigue Blog – Year in Review

During 2017 the SMDI Bar Steel Fatigue sub-committee continued work on numerous studies, test protocols, as requested by the committee members who represent key ground vehicle OEMs and suppliers. The committee continues to concentrate test efforts on those steel grades … Continue reading

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Carburized Case-Core Samples

In this article we will examine Iterations #62, #63 and #70. These are carburized samples with a case/core composite to simulate an actual carburized part. Until now, all of the carburized samples we have looked at have been through carburized … Continue reading

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Strength and Fatigue Life versus Carbon Content at High Hardness (60 HRC)

The strength, fatigue and hardness data for several iterations with a high hardness level, around 60 HRC are shown in Table 1. The steels in these iterations are both plain carbon and low alloy grades with carbon contents ranging from … Continue reading

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Additional Data on the Effects of Cooling Rate on the Overload Fatigue Properties of Carburized Steels

In the previous post (Dec. 30, 2016), the effects of cooling rate on both constant amplitude and overload core fatigue properties of a carburized Ni-Cr-Mo alloy steel (4320) were compared.  As was noted, the study involved subjecting steel bars of … Continue reading

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Effect of Steel Composition on the Case and Core Fatigue Properties of Low Alloy Carburized Steels

In earlier posts, limited data indicated that the fatigue properties of the cores of carburized components do not vary significantly with the composition of low alloy steels.  There was evidence, however, that the fatigue properties of the cases of carburized … Continue reading

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