Austempering/marquenching powder metal parts

a technology of metal parts and marquenching powder, which is applied in the field of austempering/marquenching powder metal parts, can solve the problems of reducing bending fatigue strength, limited use, and lowering wear resistance, and achieves the effect of high performance powder and medium to high density
US20060182648A1Inactive Publication Date: 2006-08-17BORGWARNER INC
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
BORGWARNER INC
Publication Date
2006-08-17
Estimated Expiration
Not applicable · inactive patent

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Abstract

A powder metal part is made by compaction at room temperature or an elevated temperature followed by sintering, a secondary densification, heat treating, and optional secondary operations. The particulate materials preferably include iron, 0-2.0 wt % copper, 0.15-0.9 wt % carbon, 0.5-2.0 wt % molybdenum, 0.5-4.5 wt % nickel, 0-4.0 wt % chromium, and 0-1.5 wt % silicon. At least one secondary densification is applied to the part after compaction and pre-sinter / sinters steps to achieve medium to high density. The secondary densification is part of a double-press double-sinter (DPDS) or is a mechanical working depending on the application requirements. The powder metal is heat treated by austempering or marquenching followed by tempering. A unique composite microstructure is achieved from austempering by controlling the powder chemistry and the holding time at an elevated temperature. The combination of a secondary densification and austempering or marquenching produces a high performance powder metal part for demanding applications.
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Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention pertains to the field of powder metallurgy. More particularly, the invention pertains to the formation of a high-performance powder metal part using a manufacturing process including a secondary densification and austempering or marquenching as a heat treatment.

[0003] 2. Description of Related Art

[0004] Powder metallurgy manufacturing processes have been successfully used to produce powder metal parts while providing various advantages. Such powder metal parts can be made into a variety of complex shapes with minimal steps, and with little or no finishing machining. Powder metallurgy also enables a high-volume of metal parts to be produced in an economic fashion. Powder metallurgy processes have been found to be more energy efficient than other processes involving forging and outright machining.

[0005] Secondary densifications of powder metals followed by heat treatment are known in the art.

[0006] U...

Claims

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