JPS5855223B2 - Heat-resistant and wear-resistant Cr↓-Fe↓-Ni↓-Co-based alloy - Google Patents

Description

Detailed Description of the Invention The present invention provides Cr-Fe-Ni-Co which has high strength, excellent wear resistance and corrosion resistance at room temperature and high temperature, and also has excellent castability and overlay weldability. It concerns base alloys.

Conventionally, manufacturing of cast members such as valves and valve seats of automobile engines, valves and valve seats of chemical industrial equipment, and blades of turbines and pumps, and wear of the valves and valve seats and the casings and blades of pumps, etc. It has high strength, excellent wear resistance and corrosion resistance at room temperature and high temperature, and also has excellent castability and overlay weldability for overlay welding on rough parts, such as the tip of a knife. Co-based alloy, for example, C: 0.9 to 1.4%, Mn: 1.00 or less, W: 3. O to 6.0 ratio, Ni: 3.00% or less, Cr: 26.0 to 32.0%, Mo: 1.00% or less, Fe: 3.00 width or less, Si: 2.00 ratio or less, Co and other unavoidable impurities: Remaining Co-based alloys (American Welding Standards 5.1
3-70 RCOCR-A) is used.

Conventional Co-based alloys with the above composition have excellent properties as described above, but because the Co content always accounts for 50 parts or more,
Currently, it has to be expensive, and therefore its use is limited to a limited number of fields.

Therefore, from the above-mentioned viewpoint, the present inventors have attempted to reduce the content of expensive Co as much as possible, and in addition, the conventional C
As a result of conducting research to obtain an alloy with properties almost equivalent to those of the O-based alloy at a lower cost, it was found that even if the Co content was less than half that of the conventional Co-based alloy mentioned above, the reduction in Co content It was found that the deterioration in alloy properties can be covered by the inclusion of Fe y Nis and Mo, and excellent properties are maintained.

Therefore, this invention was made based on the above knowledge, and in weight %, c: i, o~3.5 ratio, Mn: 0.5~2.0%, W: 2.0~10 .0 ratio, Cr: 25.0-35.0%, Mo: 2.5-7.5'lr, Fe: 20.0-30.0%, Ni: 18. Cr-Fe- having a composition consisting of Co and unavoidable impurities: Io, 0 to 23.0 Hiroshi, and further containing V: 0.5 to 2.0 Hiroshi, if necessary. This is a characteristic of Ni-Co based alloys.

Incidentally, among the inevitable impurities in the alloy of this invention, S
i and Nb are Si: 1.00 or less, Nb: 0.
Permissible within a range of 5% or less.

Next, the reason why the composition range of the alloy of the present invention is limited as described above will be explained.

(a) C The C component combines with W, Mo, Cr, and However, if the content is less than 1.0%, the desired effect cannot be obtained;
．． If the content exceeds 5%, the impact resistance of the alloy will decrease, so the content was set at 1.0 to 3.5%.

(b) Mn Mn is added for the purpose of deoxidizing the molten metal and improving overlay weldability, but if its content is less than 0.5%, the desired deoxidizing and desulfurizing and improving effects are ensured. I can't do it,
Moreover, if the content exceeds 2.0%, overlay weldability and workability will deteriorate, so the content is set at 0.5 to 2.0%.

(c) W and Cr As mentioned above, W and Cr combine with C to form carbides and have the effect of improving hardness.
i-Co acts as a solid solution in the matrix to strengthen the matrix, but its content is less than 2.0% W and less than 2.0% C.
When r: less than 25.0%, desired high temperature hardness and high temperature strength cannot be secured, while when W: 10. O%, Cr
: If the content exceeds 35.0%, the machinability (
Since the grindability) and build-up weldability deteriorate, the content is reduced to W: 2.0 to 10.0%.
Or: 25.0 to 35.0%, respectively.

(d) M.

Like W and Cr, the Mo component has the effect of forming carbides and solid solution in the austenite matrix to improve the high-temperature hardness and high-temperature strength of the alloy, but its content is less than 2.5%. However, if the content exceeds 7.5, the oxidation resistance of the alloy decreases, so the range of 2.5 to 7.5 was determined.

(e) Fe, NiV and C.

In order to keep the Co content as low as possible, and to ensure properties comparable to the room temperature and high temperature properties of the above-mentioned conventional Co-based alloys, which have extremely high Co contents, the Co content should be at least 10. It is necessary to set the maximum content of Fe and Ni to 30% (Fe: 1%, Ni: 25.0%), and the upper limit of Co (23%) determined from an economical point of view.
．． In the 0 ratio, the minimum content of Fe and Ni is Fe: 20.
0%, Ni: 18. An O person is required.

For this reason, Co content: 10.0 to 23.0%, Fe content: 20.0 to 30.0%, and Ni content: 18 and O to 25.0%, respectively.

(f) At V v1, it forms fine carbides that are difficult to coarsen, and also strongly stabilizes Cr and W.
, and W, etc., it is alloyed with these components to stabilize the alloy structure and improve high-temperature hardness. However, if the content is less than 0.5%, the desired effect cannot be obtained, and if the content exceeds 2.0%, the toughness will decrease. must be between 0.5 and 2.0%.

The upper limit values of Si and Nb as unavoidable impurities were set as Si: 1.00% and Nb: 0.5% because if Si exceeds 1.00%, thermal shock properties deteriorate; On the other hand, this is based on the reason that if the content of Nb exceeds a factor of 0.5, overlay weldability deteriorates.

**Next, the alloy of the present invention will be explained using Examples while comparing it with the above-mentioned conventional Co-based alloy having a high CO content (hereinafter referred to as conventional alloy).

Alloys 1 to 7 of the present invention and conventional alloys having the fractional compositions shown in Table 1 were manufactured by a conventional melting and casting method.

In addition, in producing both of the above alloys, regarding the same ingredients,
The fractions whose mutual contents have substantially the same range, ie, the contents of Mn, W, and Cr, were made substantially the same.

Next, for the alloys 1 to 7 of the present invention and the conventional alloys prepared in this way, Rockwell C) and 8
The high temperature hardness (Vickers) at 00°C was measured, and further, ■ Molten lead oxide heated to 915°C: 40. ! A high-temperature corrosion test in which a sample of both of the above alloys with dimensions of 12 mm in diameter x 12 nm in height was immersed in 7 for 1 hour and the weight loss was measured. A castability test in which the molten metal was cast into a mold at a temperature of 1500'C and the casting distance was measured.
Using the above-mentioned Ryokaikain welding rod specimen, welded a single layer of annular beads with a width of 20 mm and an outer diameter of IQQmi on the top surface of the 316 base metal using a 02+02H2 gas automatic welding machine, as shown below. Overlay weldability test in which the alloy with a bead formed on the top surface is heated to a temperature of 700'C, held for 15 minutes, and then water-cooled repeatedly, and the number of operations until cracks occur in the bead part is measured. , respectively.

The results are shown in Table 2. As is clear from the results shown in Table 2, the alloy of the present invention has a very high Co content of approximately 63%, compared to the conventional alloy, which has a very high Co content of
Although it has a significantly low coefficient of 22, it has excellent properties that are almost equivalent to conventional alloys.

As mentioned above, the alloy of the present invention has significantly lower carbon content than conventional alloys with high Co content, which have high strength and excellent wear resistance, corrosion resistance, castability, and overlay weldability.
The alloy has excellent properties comparable to those of the conventional alloys in terms of o content, and the economic significance brought about by this is extremely large.

Claims (1)

[Claims] IC:1. O~3.5 ratio, Mn: 0.5~2.0%, W: 2. O~10.0%, Cr: 25.0-35.0%, Mo: 2.5-7.5%, Fe: 20.0-30.0%, Ni: 18. O~25.0%, Co and inevitable impurities: 10.0~23.0%,
Heat-resistant and wear-resistant Cr having a composition consisting of (the above weight range)
-Fe-Ni-Co based alloy. 2C:1. O-3.5 ratio, Mn: 0.5-2.0%, W: 2.0-10.0%, Cr: 25.0-35.0%, V: 0.5-2.0 ratio , Mo: 2.5-7.5%, Fe: 20.0-30.0%, Ni: 18. O~25.0%, Co and inevitable impurities: 10.0~23.0%, (
Cr-
Fe-Ni-Co based alloy.