JP2003293011A - Iron-based wear-resistant sintered compact free from hostility to mating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost, high-performance, wear-resistant iron-based sintered article free from hostility to a mating material. <P>SOLUTION: The composition of powder is formed into the matrix composition of hardened ingot high-speed steel. The resultant sintered compact functions as a hostility-free wear-resistant material. The characteristics of the sintered compact are not influenced by sintering temperature for its green compact. Because the sintering temperature for the green compact can be freely selected, low-cost atomized powder can be used and the total-cost reduction can be attained. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the provision of a low-cost, high-performance, wear-resistant, iron-based sintered product that does not attack a counterpart material. [0002] The performance and cost of an iron-based sintered body are related to the composition of the powder used, the production method, the sintering behavior and the like. Since the high-speed steel completed as a smelting material is the best iron-based wear-resistant material, this composition has been followed for a sintered body intended for the wear-resistant material. Sprayed powders have been employed because iron-based alloy powders are inexpensive. The reason why the sintered body is used is that it is easy to give a shape close to the final shape and it is possible to avoid waste of material on the way. The high-speed steel as a representative and an example refers to a normal standardized steel. [0003] Since high-speed steel is originally intended as a cutting tool, it is necessary to use an object which must not attack a mating material with which it comes into contact, whether it is a molten material or a sintered material. Not suitable for materials. Furthermore, free sintered bodies obtained from sprayed powders of high speed steel composition lack toughness. Accordingly, in the present invention, the composition of the powder is changed to the substrate composition of the quenched high-speed steel. Substrate composition is C 0.4-0.6, W 7-10 (T type), Mo + W 5-7 (M type), Cr
4-5, V1-2, Fe + Co balance, weight% (references: F. Kayser & M. Cohen, Metal Progress, June1952, p7
9) Although there are some differences between the types, there is almost no difference between the classes. Further, in order to meet the demand for a strict cost / performance ratio for the sintered body, the manufacturing method of this powder is referred to as a spraying method. The aggressiveness of a high-speed steel which is heat-treated for use is attributed to the precipitated M ₆ C carbide. The fact that high-speed steel functions as a cutting tool material even in the glowing state is evidence that the substrate itself is a strong wear-resistant material. The substrate, unlike the grindstone binder, functions more than the carbide support. [0006] Although any iron-based alloy can be spray-pulverized, this does not mean that the resulting spray powder can be free-sintered soundly. For example, the spray powder of the high-speed steel composition is too coarse, and the compact does not become dense unless it is in the quenching temperature range. Therefore, the sintered body has a brittle cast structure, though varying in degree. In contrast to smelting high-speed steel, it is similar to receiving unforged. Conversely, the compact of the matrix composition powder always results in the same material having high toughness no matter how many times it is sintered. This is illustrated by fact. The matrix composition of the M4 high speed steel is 3.5W-3.2Mo-4.7Cr-1.9V-0.5C-86.1Fe, wt% (see references above). Patent application 2001-21
Some of the compacts obtained by using the method described in 1505 and ignoring the restrictions include those which are sufficiently removed of oxygen and then sintered at a temperature of 1200 ° C. or more for 1 hour to sinter to 95% or more of the theoretical density. The minimum temperature at which the sintering can be performed, 1200 ° C., is unique to the molded body (hereinafter, the intrinsic sintering temperature). The sintered body obtained by sintering the molded body at a temperature of 1210 ° C. or 1300 ° C. is hot isostatically compressed at 1150 ° C. and 152 MPa for 1 hour, and then compressed at 1210 ° C. for 3 hours.
And quenched in oil at 550 ° C for 90 minutes (once) for 5 minutes.
Tempered at 60 ° C. for 90 minutes (twice). Depending on the sintering temperature, the flexural strength is 4.22 or 4.32 GPa and the hardness is 59.8 or 59.7 HRC
Became. Number of repetitions 4. Since there is no difference in flexural strength sensitive to the structure or the like, both sintered bodies may be regarded as the same. The carbon analysis value was 0.52% and the oxygen analysis value was 0.0097. [0008] Substrate composition of T4 high speed steel 8.3W-0.5Mo-4.7Cr-
For molded or sintered compacts with 1.1V-5.6Co-0.4C-79.5Fe, intrinsic sintering temperature 1225 ℃, sintering temperature 1240 ℃ or 1320 ℃, isotropic compression temperature 1200 ℃, quenching temperature 1260
° C, bending strength 5.06 or 5.05GPa, hardness 58.2 or 57.9HRC,
Carbon analysis value 0.35, oxygen analysis value 0.011%. [0009] Both types of sintered bodies, especially the T4 type, are rich in toughness. In-situ measurements for high speed steel with hardness (references Masao Kondo, Bulletin of the Institute of Metals vol.5, No.8 (1966), p
The reason that the carbon value in the substrate composition is lower than that of 501) is probably underestimated due to the limitation of the analytical method (the above-mentioned reference). The carbon value, apart from the true value, shall be determined conveniently for me. According to the present inventors, the properties of the exemplified sintered body do not depend on the sintering temperature, not only because of the special properties of the powder or compact used, but also because of the substrate composition. You. Therefore, it is possible to reduce the cost of the sintered body by employing inexpensive spray powder, which is the object of the present invention. Spray powder was originally intended for high speed steel constrained sinters and is sufficient. When used for a free sintered body, the powder is too coarse, the intrinsic sintering temperature falls within the quenching temperature range, and the sintered body becomes brittle like a cast material. Conversely, since the compact having the matrix composition does not have enough M6C carbide to form a liquid phase in the quenching temperature range, the resulting sintered body is always sound regardless of the intrinsic sintering temperature. is there. [0011] In terms of the general usability of a powder of a substrate composition which is substantially alloyed, typically a spray powder, sintering may be concentrated only on densification of the compact, and the compact necessarily requires fine powder. No, so the production of spray powder improves the yield, etc. Regarding the composition of the wear-resistant iron-based sintered body that does not attack the counterpart material, the substrate composition is the first answer. The improvement of high speed steel composition of the predecessor over a hundred years is a corresponding improvement in the composition of the substrate. The uniqueness of the substrate composition found empirically suggests that the composition is determined as a matter of nature and is therefore the optimal composition. Therefore, nothing is better than this composition. The cost reduction intended in the present invention is energy saving as well as economy.

Claims (1)

Claims: 1. A low-cost and high-performance-oriented spraying powder characterized by using a spray powder having a substrate composition of a conventional high-speed steel quenched in an iron-based wear-resistant body that does not attack a counterpart material. Sintered body.