Category Archives: News

Mechanical Properties and Fatigue Strength of the Early Through-Carburized Samples

In this article we will examine the mechanical properties and fatigue strength of the early through-carburized iterations in the SMDI fatigue program. During this time period the test bars were typically ground and polished after carburizing in order to eliminate … Continue reading

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Hardness versus Fatigue Strength

In the previous article we examined the relationship between hardness and tensile strength for the AISI fatigue database iterations through 141. As the hardness increased the tensile strength also increased for a majority of the steels and the relationship was … Continue reading

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Hardness versus Strength

There is a very good relationship between hardness and strength for steel. If the hardness is known the tensile strength can be estimated, and the reverse is also true. This relationship is valid for tensile strength but not for yield … Continue reading

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Effect of Intergranular Oxidation on Axial Fatigue Test Bar Performance

Two 100 pound heats of vacuum melted 8695 steel were made for iterations 40 and 41. This chemistry represents the case of carburized 8620 steel. The two heats were forged into bar stock from which axial test bars were machined. … 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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Carburized Core Properties When Hardness is Controlled by Cooling Rate

In the previous article we examined the relationship between the core hardness of carburized steels to both strength and fatigue. In that study the hardness was controlled by the tempering temperature used during the quench and temper heat treatment. In … Continue reading

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Carburized Steel Core Strength and Fatigue Life as a Function of Hardness

In this article we will examine the strength and fatigue life found in the core of a part when using typical low carbon alloy carburizing steels. Table 1 shows the data found with this type of material and heat treatment … 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 Cooling Rate on the Overload Fatigue Performance of Carburized Steels

In earlier posts, the effect of cooling rates on the core fatigue properties of carburized steels were examined.  The study involved subjecting low alloy steel bars of various diameters to a carburizing thermal cycle without the presence of carbon in … Continue reading

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Effects of Sulfur and Overloads on the Fatigue Performance of Low-Alloy Steels

In earlier posts, the effect of sulfur on the fatigue performance of low-alloy steel was examined.  It was noted that sulfur is present as manganese sulfides in steels, and these sulfides are highly plastic at hot working temperatures.  During hot … Continue reading

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