JPS5873701A - Production of powder metal forged parts having excellent hardenability and toughness - Google Patents

Abstract

PURPOSE:To produce powder metal forged parts having excellent hardenability and toughness at los cost by using the Cr-Mn low alloy powder of ultra low oxygen produced by an oil spraying method as a raw material for the powder metal forged parts. CONSTITUTION:The melt of inexpensive Cr-Mn low alloy steel having excellent hardenability is pulverized in an oxidation-free state by an oil spraying method using nonpolar solvents mineral oils, vegetable oils, etc. After such Cr-Mn low alloy steel powder is degreased, oxide powder of Cr-Mn low alloy steel is added as a decarburizer and a small amt. of lead stearate is added as a lubricant thereto and these materials are thoroughly mixed and molded under pressure, whereby green compacts are produced. The green compacts are heated and sintered in an inert gaseous atmosphere and during the course thereof, the raw material powder steel is decarburized by oxides and is then hot-forged, whereby the powder metal forged parts which contain extremely less oxygen, and have excellent roughness and hardenability are produced inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention uses non-polar solvents as mv & mineral oil %
Some clays are made from VhCr-Mu based low alloy steel powder, which is made by oil spraying using animal and vegetable oils, decarburized and annealed, and has good hardness and toughness. The present invention relates to a method for manufacturing powder forged products with excellent quality.

As a raw material for powder forging, water spray powder is considered to be optimal for both iron'8 powder and composite steel powder in terms of performance and price. Hardenability and price are important issues for alloyed copper powder used in certain parts.

Ni-M has traditionally been used when manufacturing, for example, passenger car parts.

(4600) - Powder is insufficient. Therefore h
It is essential to use alloy powder* containing cr and MB.
Substitution to CrlMu is effective even in low-priced F.

However, compared to Cr, Mn, Fi, and Ni & Mo, it is difficult to reduce as soon as it is oxidized during water spraying and the formed oxide is relatively stable, resulting in a high oxygen content.
Compounds act as non-metallic inclusions and deteriorate the toughness of powder forged products.

It is difficult to reduce the amount of oxygen in Cr-Mn copper powder at the powder stage, and it is necessary to increase the sintering temperature in the manufacturing process of one part to reduce the amount of oxygen in the forged part.

However, even if a high i sintering temperature is used, a large amount of oxides remain, reducing the toughness of the forged product and having a negative effect on the hardenability. According to experiments, the oxygen content is 0.02
If it exceeds 96, the impact value spread will drop significantly, but powder forged products made by the conventional water spray method contain a large amount of at least 0.3 inches.

Therefore, the hardenability is at least as good as that of rolled steel.

Cr--steel powder, which has good toughness and is aimed at low cost, has various problems with Mazai's manufacturing method, and the technology for mass production has not yet been established.

In view of the current situation, the present invention proposes ultra-low oxygen Cr-un produced by the oil spraying method previously invented by the applicant and subjected to only degreasing treatment without decarburization or annealing treatment.
Using steel powder as a raw material and using existing equipment, powder forged products with high toughness and high hardenability with few nonmetallic inclusions can be obtained.
This paper proposes a manufacturing method for A, which is characterized by the oil spray method. Using cheaper raw material powder,
Moreover, manufacturing costs can be significantly reduced by decarburizing during the sintering process.

That is, in this invention, molten metal is pulverized by an oil spraying method using a nonpolar solvent, mineral oil, or animal and vegetable oil as a spraying medium, and then only degreased and undecarburized C.
A green compact obtained by compression molding a raw material powder obtained by mixing r' MH-based low alloy steel powder with an oxide of the above low alloy steel powder as a decarburizer is heated and sintered, and in the sintering process, The purpose of this method is to decarburize and then hot forge to produce powder forged products with excellent hardenability and toughness.

The raw material of this invention is an ultra-low oxygen alloy steel made by an oil spraying method, and the oxides present in the steel can be easily reduced, so it is sufficient to hold the steel at 1200° C.K. for 15 to 30 minutes for sintering. And: The sintering protective atmosphere gas is a mixed gas of inert gas and orphan gas.

It is possible to use ammonia decomposition gas, propane gas, and butane decomposition gas.

1 Also, since the raw material has not been decarburized, it contains medium carbon, and the oxygen from the decarburizing oxide mixed with the raw material during the sintering process decarburizes it and makes it low carbon. That makes me angry.

In this case, since carbon is dissolved as a solid solution in the copper powder, the deoxidation reaction easily proceeds, and the amount of residual oxygen can be reduced to 91091 m by sintering at 1200° C. and 30 m1, for example.

Next, specific examples of the present invention will be described. Example 1 Co, ss*%Mno, ys*, Cr 1°ozs
, Me O, 24 Chi, 0, 0.031! , the remainder being substantially KF, oil-sprayed copper powder 68-, and CG
, 06'11. ldsα75L Cr1.02%,
A raw material prepared by adding a trace amount of lead stearate as a lubricant to a mixed powder of Me O, 24g6. Cold compacted to make a green compact with density &80P/cc, inert ffX 5IsH, -959GN, dew point -
The green compact was placed in a sintering furnace using a 30°C incubation atmosphere gas, and heated to 1200°C x 391ml for sintering.
A powder forged product was made by hot forging at a temperature of 1,000°C with the addition of a lot/- of retainers. The final product obtained is CG, 261
6. o, 0.0099h, density? , 85 f/cc
Example 2 20% copper powder by oil spraying with the same ingredients as Example 1,
CO, 57es1Mn O, 75%, Cr 1.0
2ts1MoO, 24%, 0.0.90%, the balance was essentially Fc, a mixed powder of 80% forced oxide was added with a trace amount of 'phenol resin as a binder, and 6t/cd of power was added. and cold compressed to a density of 5.3 no/c.
Make a compressed body of c, inert gas 5%)I□-9≦96N
The green compact is placed in a sintering furnace using a film-holding gas with a dew point of -30'C, heated to 1200" (J +2) A powder forged product was made by hot forging by adding a reduction blade of 10 t/m' at a temperature. The final product obtained was CO, 26'16.0, 0.
0085%, and the density was 7.85 f/cc.
゛As seen in Examples 1 and 2 above, when using a mixed raw material of copper powder and a soft decarboxylation agent sprayed with hard oil, and when using the mixed raw material of copper powder and hard forced oxidation powder as described above, Even if there is a difference of 1 degree between use and use, the quality of the final product of the Powder Song forged product is the same.

Applicant: Sumitomo Metal Industries, Ltd. ← 1 Agent: 1) Ryo ゛” - Continued from page 1 ■Inventor: Katsu Nishiguchi, Sumitomo Metal Industries, Ltd., Central Technology Research Laboratory, 1-3 Nishichoshu Hondori, Amagasaki City

Claims (1)

[Claims] The molten metal was pulverized by an oil spray method using a non-polar solvent, oil, or animal and vegetable oil as a spraying method, and the molten metal was only degreased. The oxide of the above-mentioned low-alloy steel powder is mixed with the low-alloy steel powder as a decarburizer, and the powder obtained by compression molding is heated and sintered. A method for producing a powder forged product with excellent hardenability and toughness, characterized by hot forging after charcoal production.