JPH05503318A - Manufacturing method of high hardness sintered member and metal powder mixture - Google Patents

Abstract

The invention proposes a metal-powder blend which can be produced simply and can be used to manufacture high-strength wear-resistant cylinder parts to tight dimensional tolerances. This metal-powder blend consists of a steel powder formed by atomizing a steel melt and mixed with 0.3-0.7 % by wt. of graphite, the steel powder consisting of: max. 0.02 % by wt. C; max. 0.03 % by wt. Si; ).05-0.25 % by wt. Mn; 2.5-5.0 % by wt. Ni; 0.2-1.5 % by wt. Mo, remainder iron and the usual impurities and the blend contains in addition 0.7-1.5 % by wt. of finely divided Cu, with the provision that the weight ratio of Cu:graphite lies within the range 1.4-2.5.

Description

[Detailed description of the invention] name of invention metal powder mixture The present invention provides a method for producing martensitically hardened sintered parts with high hardness. Based on steel powder produced by atomization of alloy melt, 0.3 to 0.7 weight Regarding the metal powder mixture, which is mixed with % graphite powder.

The term high hardness sintered member is used in this specification to mean at least 55ON/+i■2 It is understood that a member has a tensile strength of .

European Patent No. 013616981 for producing sintered parts with high hardness of, C maximum 0.02% Si maximum 0.1% Ni　O, 4-1.3% Cu　0.2~0.5% Mo　0.1~0.3% Mn maximum 0.3% N maximum 0.01% (weight%) Remaining Fe and normal impurities A steel alloy powder consisting of

The alloy powder can be manufactured and processed at low cost, has good press properties, and has A high degree of hardness is guaranteed in the sintered finished parts. Achievement in finished parts Possible measurement accuracies are not described in detail in the document.

Pressed parts made from steel powder usually undergo a change in geometry due to sintering. Ru. This is so-called sintering collapse loss.

In principle, martensitic hardening results in a change in structure accompanied by an increase in volume. This effect is contradictory.

Of course, the volume of the finished part relative to the pressed product used for sintering This change is also taken into consideration when fitting into a press tool. In other words, the capacity error is anticipated and the attempts to achieve equilibrium from the outset through changes in the capacity of the space products. But this Attempts have so far met with little success, as the relative volume error is It depends not only on the thickness of each wall of the workpiece (also within the same stamped workpiece). There are also variations between individual samples of pressed products of the same type, and there are even larger variations. It also depends on the density achieved in the stamping, which has a significant influence. that limit In this study, efforts were made to obtain volumetric consistency and deformation of sintered finished parts made from alloy processing raw materials. However, in favorable cases, the reproducible limit of capacity error has so far been approximately ±0. ．． Only values up to 1% were obtained. For many parts, such an error body It is no longer acceptable.

For this reason, the sintered member has been subjected to measurement operations many times and the results have been confirmed. This is extremely costly. However, for hardened parts, this operation is This is no longer possible due to the hardness of the material.

The object of the invention is to create a sintered part that can be manufactured with as little expense as possible, has high hardness and is resistant to abrasion. It is to report metal powder mixtures that are allowed to be manufactured into materials, sintered and pressed. There is no need to add any more structural standards to press tools for manufacturing products, and sintered parts We report a metal powder mixture that can maintain the volumetric error within a tolerance range of up to ±0.05%. Is Rukoto. Metal powder is used in the baking of pressed products produced by normal compression operations. It should possess the property of not causing significant shrinkage or expansion upon binding.

This object is achieved by the mixing of metal powders, which is a feature of claim 1. This mixture Advantageous other compositions of the article are reported in the following claims 2 to 6.

In contrast to the known steel alloy powder described in European Patent No. 013616981, According to the invention, the Cu component is not added to the sprayed alloy, but is added to the steel powder as a fine powder. Mix in shape. Furthermore, the amounts of the individual alloying elements are according to the known steel powder. It is maintained at different limits.

Particularly essential is the Cu content, which is graphite mixed into steel powder in powder form like carbon. The ratio of Ru.

Strict observance of all the conditions of claim 1 results in the following: , and under customary sintering conditions, it is almost sufficient, independent of the wall thickness of the stamping. It is amazing that we have been able to successfully produce a press-formed product that exhibits a constant volume. capacity The deviation was less than ±0.05%・ Air cooling or a gas shower installed in the cooling zone of the sintering furnace (e.g. installed (under inert gas pressure) gives high hardness (over 750N/ma+”) A completely martensitic crystal texture is formed in the sintered part, which can no longer be heated. There is no need to reason.

The following examples provide a detailed explanation of the invention.

Steel powder was produced by water spraying of the melt with the following composition (wt%) : CO, 01% SiO, 02% Mn　O, 10% Ni 4.0% Mo 0.5% P 0.020% SO, 010% Remaining Pe and normal impurities After water spraying, the steel powder is dried and reductively quenched at approximately 1000°C in a hydrogen atmosphere. I did this. After cooling, the resulting coagulum was ground into a fine powder. The residual oxygen content of the steel powder The content amounted to about 0.15% and its density was about 3 g/cm'.

The steel powder was followed by 0.60% graphite powder and 1.0% finely divided Cu. Approximately 1% of a conventional lubricant was added.

After uniformly mixing these ingredients, the pressed product is cooled and compressed in the usual manner. The density of the pressed product was approximately 7 g/cm3.

After sintering the press work at approximately 1120°C, the finished part is coated with the press work. A capacity error of ±0.03% or less was produced with respect to the scale. The parts are subjected to nitrogen shower after sintering. It completely hardens to martensite when cooled under It exhibited a tensile strength of 82ON/+am'' or more.

In another experiment using the metal powder mixture of the present invention, 800°C and 1120' Double compression and sintering technology was applied to the pressed product at a temperature stage of C. At that time, the corresponding pair Due to the sintering process, the capacity error was less than 0.03% in each case.

The tensile strength was approximately 90 ON/m+i'' and the hardness was approximately 450 HB.

The advantage of the metal powder mixture according to the invention is that sintered parts of constant volume can be produced, in particular Expensive post-sintering mechanical, deformation or thermal processing is no longer necessary. Moreover, the steel powder is produced in a cheap manner. That is, the original Through water spray and subsequent reduction in a hydrogen atmosphere, can be used. Expensive vacuum hardening is not required for other alloyed and water sprayed metals. This kind of vacuum quenching is necessary for powders for similar purposes. is not necessary in this method. In addition, inexpensive manufacturing methods combine with excellent hardness and wear properties. attached.

Submission of translation of written amendment (Article 184-8 of the Patent Act) July 17, 1992 prisoner

Claims (6)

[Claims] 1. Steel alloys for manufacturing martensitically hardened sintered parts with high hardness. 0.3-0.7% by weight, based on steel powder produced by atomization of gold melt In a metal powder mixture mixed with graphite, the above steel alloy powder (wt%): C Maximum 0.02% Si maximum 0.03% Mn　0.05~0.25% Ni 2.5-5.0% Mo　0.2~1.5% Remaining Fe and normal impurities The mixture consists of finely divided Cu with a Cu/graphite ratio of 1.4 to 2. ．． A metal powder mixture characterized in that it contains a metal powder mixture in an amount of 0.7 to 1.5% in a proportion in the range of 5. Compound. 2. Characterized by the fact that the Mn content is limited to a value of 0.10 to 0.20%. The metal powder mixture according to claim 1. 3. A claim characterized in that the Ni content is limited to 3.0 to 4.0%. The metal powder mixture according to items 1 and 2. 4. A claim characterized in that the Mo content is limited to a value of 0.5 to 1.0%. The metal powder mixture according to any one of claims 1 to 3. 5. Claim 1 characterized in that graphite addition is limited to 0.5 to 0.6%. 4. The metal powder mixture according to any one of Items 3 to 4. 6. Any one of claims 1 to 5, characterized in that the Cu/graphite ratio is 2. The metal powder mixture according to item 1.