Iron-based sintered alloy material and production method therefor

Pending Publication Date: 2020-10-22
HITACHI CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is about a material made from iron that can be used to make various products like machinery parts. By using this material, we can create products that are cheaper and have better precision. This material has a hardened layer on its surface that improves its fatigue strength, wear resistance, and reduces thermal strain. This makes it a useful material for making components that can withstand high levels of stress and have better performance.

Problems solved by technology

Carburizing treatments represent a hardening method that has been used for a very long time, and are in widespread use, but the size of the strain generated as a result of the quenching that is conducted as a heat treatment following the carburization is problematic.
On the other hand, nitridization treatments that use precipitation strengthening by nitrides enable the treatment to be conducted with a lower heating temperature than carburizing treatments, and can therefore reduce the amount of thermal strain, but the length of the treatment time and the thinness of the hardened layer are problematic.
Further, despite being hard, nitrides tend to be brittle, and therefore also suffer from problems of strength.
However, the drawbacks of long treatment times and shallow hardened layers still exist in nitriding treatments.

Method used

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  • Iron-based sintered alloy material and production method therefor

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0048](Sample 1)

[0049]A graphite powder was blended with an Fe—Cr—Mo—Mn alloy powder and mixed uniformly to prepare a raw material powder having an overall composition (% by mass) containing 0.5% of Cr, 0.2% of Mo, 0.2% of Mn, 0.5% of C, and the remainder as Fe. Using this raw material powder, molding and sintering were conducted in the manner described below.

[0050]A mold having a ring-shaped cavity with an outer diameter of 50 mm, an inner diameter of 30 mm and a length of 6 mm was prepared, and the raw material powder was placed in the cavity and compressed using a punch, thus forming a green compact with a green density of about 7.2 Mg / m3. This green compact was installed in a sintering furnace and heated at 1,200° C. in a mixed gas atmosphere containing 90% nitrogen and 10% hydrogen, and following sintering for 60 minutes, the temperature inside the furnace was lowered, obtaining an iron-based sintered alloy substrate of sample 1. The density was measured by the Archimedes princ...

example 2

[0067]A mold having a cavity for molding a sprocket for a variable phase system with an over-pin diameter of 94.425 mm was prepared. An Fe—Mo—Ni alloy powder, a graphite powder and a molding lubricant were blended to prepare a mixed powder having an overall composition (% by mass) containing 0.55% of Mo, 0.55% of Ni, 0.25% of C, and the remainder as iron and unavoidable impurities, and using this mixed powder as a raw material powder, the same operations as Example 1 were conducted to produce an iron-based sintered alloy substrate having a sprocket shape. Subsequently, the teeth of the sprocket were subjected to a rolling treatment to densify the outermost surfaces of the teeth.

[0068]Using the above substrate, nitroquenching or carburizing quenching was performed in the same manner as Example 1, thus obtaining a sprocket-shaped iron-based sintered alloy material having a hardened layer formed at the surface. However, the nitriding temperature was set to 700° C. and the carburizing t...

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Abstract

An iron-based sintered alloy material having, at the surface of the material, a hardened layer exhibiting a martensite phase containing a solid solution of nitrogen in a supersaturated state. The iron-based sintered alloy material may contain at least one of chromium, copper, molybdenum, manganese and nickel. A production method for the iron-based sintered alloy material includes: subjecting an iron-based sintered alloy substrate containing carbon to a nitriding treatment by heating the substrate to a nitriding temperature of at least 590° C. in an atmosphere containing ammonia, and then performing quenching by rapidly cooling the substrate.

Description

TECHNICAL FIELD[0001]The present invention relates to an iron-based sintered alloy material having a hardened surface and increased strength, and a production method for this iron-based sintered alloy material.BACKGROUND ART[0002]Surface treatments using chemical hardening methods have conventionally been used to impart metal materials with the types of material characteristics such as wear resistance and fatigue resistance required for machinery components and the like. Chemical hardening methods are methods in which a hardening component acts upon the material surface to form a hardened layer on the surface, and include a variety of treatment methods such as carburizing treatments, nitridization treatments, nitriding treatments, carbonitriding treatments, sulfonitriding treatments and boronizing treatments. Carburizing treatments represent a hardening method that has been used for a very long time, and are in widespread use, but the size of the strain generated as a result of the ...

Claims

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Application Information

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IPC IPC(8): B22F3/24C22C38/22C22C38/20C22C38/04C23C8/26
CPCB22F2302/20B22F3/24C22C38/22C22C38/04C22C38/20C23C8/26B22F2003/248B22F2301/35C23C8/22C21D1/18C21D6/004C21D6/005C22C38/58C22C38/44C21D2211/008C22C38/00C23C8/02C23C8/80B22F3/12B22F2998/10B22F2201/02B22F2201/016C22C33/0264B22F2999/00B22F5/106B22F3/02B22F3/10
Inventor OMORI, HIROSHI
Owner HITACHI CHEM CO LTD
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