Analysis of Failed Wheel

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Failure Analysis Services and Materials Testing

发布日期: 2024年3月12日
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Introduction:

A failed industrial machine wheel section was submitted for evaluation of the hardening pattern, mechanical properties, chemical composition, and to characterize the cracks in the roller path.? The wheel is specified to be produced from Grade 10B60 medium carbon boron treated steel.? The wheel is further specified to be induction hardened to a surface hardness of 57 to 62 Rockwell C and hardened to 45 Rockwell C to a minimum depth of 0.130”.? It was reported that this wheel may have been subjected to elevated temperatures due to sliding friction during service.? No additional information was provided regarding the production, testing or service history of this wheel.

Visual Examination and Macroetch Evaluation:

The roller path of the submitted wheel exhibits colorations that may be consistent with heat tint as shown in Figure 1.? The heat tint colorations are present only on the roller path indicating that any heating was isolated to the roller path.? Reddish brown colorations consistent with rust are also present on the wheel.? A significant number of longitudinal cracks are present on the roller path as shown in Figures 2 to 4.? The largest cracks extend approximately 0.28” from the roller path into the wheel.? Some secondary cracks are present adjacent to the roller path cracks.? A radial section was removed from the wheel and the radial surfaces were ground. One of these surfaces was then macroetched to evaluate the hardening pattern.? The hardening pattern extends completely across the tread surface, along the flange radius and the vertical surface of the flange which indicates that it is induction hardened as shown in Figure 5.? The hardening pattern does not extend across the entire flange indicating it was not through hardened.? The visually etched case extends to a maximum depth of 0.44”. The “top” of the wheel, in relation to the orientation during quenching, was not indicated on the wheel as received.

Fig. 1 - The section of the failed wheel is shown as received.? The roller path of the wheel exhibits colorations that are consistent with heat tinting of the material.? Reddish brown colorations consistent with rust are also present on the roller path.? A significant number of cracks are present on the roller path (red arrows).? (0.5X).
Fig. 2-??? The right center of Figure 1 is shown at higher magnification.? The cracks extend from the edge of the roller path surface to the flange radius.? (1.1X).


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Fig. 3-??? The wheel section shown in Figure 1 is shown after a 90o vertical rotation.??? (0.5X).
Fig. 4-??? The upper right of Figure 3 is shown at higher magnification.? The largest crack extends approximately 0.28” from the tread surface.? A secondary crack (red arrow) is also present adjacent to the largest crack.? (1.2X).
Fig. 5-??? The macroetched radial section exhibits a uniform hardening pattern along the tread surface.? The outer surface of the flanges do not exhibit any evidence of a hardened case indicating the flanges were not completely through hardened.? The hardened case extends to a maximum depth of 0.44”.? 10% Nital.? (0.5X).

Check out our page tomorrow for the next part: Chemical Analysis

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