JPH0342024Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is intended for use in blast furnace tuyeres, which are exposed to high temperatures, are susceptible to melting due to direct contact with molten materials, and are subject to severe collision wear due to small pieces of coke, etc. The present invention relates to a tuyere tip surface structure that has excellent abrasion and peeling resistance at high temperatures.

(Prior Art) Various methods for improving the surface structure of the tuyere tip have been studied, and the following methods are known as the main ones.

(1) Metal spraying (Unexamined Japanese Patent Publication No. 49-84911) (2) Ceramic thermal spraying (Unexamined Japanese Patent Application No. 59-20411) (3) Metal diffusion penetration (Unexamined Japanese Utility Model Application No. 48-96202) (4) Carbide powder Metal welding with the addition of
-158336) (5) Colmonoy alloy welding (Utility Model Application No. 51-32603) (Problems to be solved by the invention) The above-mentioned conventional techniques each have the following problems. In other words, the mechanical adhesion strength of thermal spraying methods (1) and (2) above is usually much lower than that of welding.
In particular, in the case of (2) ceramics, the thermal sprayed layer tends to peel off early because the mechanical properties are vastly different from the copper of the main body, and furthermore, the thickness of the coating layer formed by thermal spraying is about 0.3 mm. As for the thin and heat resistant effect,
Even if some wear resistance was observed at the beginning of use, the coating layer peeled off early, so the wear resistance was extremely low.
In the metal diffusion penetration described in (3) above, since there is a mixed layer with copper in the coating layer, the hardness as a whole is diluted, and it is difficult to form a layer with uniform hardness even in the cross section of the coating layer. ) and (2), even though the heat resistance effect was observed, the wear resistance was low. In metal welding with the addition of carbide powder as described in (4) above, although the peeling resistance is improved, wear resistance is expected to be due to the microscopically high hardness portions of the added powder. From a macroscopic perspective, the overall hardness is thought to be due to the high hardness of the powder particles being diluted by the welding base material, and it is questionable whether this has sufficient wear resistance. In the Colmonoy alloy welding described in (5) above, the surface hardness decreases significantly at high temperatures, and improvements to this problem have been desired.

From the above-mentioned viewpoint, the present invention aims to provide a tuyere with excellent wear resistance that has a stable hardened coating layer that has high mechanical adhesion strength and is difficult to peel off under high temperature conditions in a blast furnace. .

(Means and Actions for Solving Problems) Next, the present invention will be explained with reference to the drawings. The tuyere body shown in the figure is made of copper casting, and has two cooling water circulation paths for water cooling in order to obtain heat resistance under high temperatures. Although this provides a certain degree of heat resistance, it is not resistant to wear caused by small pieces of coke and will lead to early breakage, so the present invention is designed to adhere to the copper base material consisting of 33 nickel groups on the surface of the tuyere tip. It is characterized by a surface structure that improves the adhesion strength of titanium carbide by providing a high-strength welding layer and further forming a welding layer made of 4 titanium carbide on this welding layer. This provides a tuyere with excellent wear and peeling resistance.

The surface structure of the tip of the tuyere was determined by a shear strength measurement test between the copper base material and the coating layer, a crack initiation test by applying thermal shock, a coating layer cross-sectional hardness measurement test, and a coating layer surface hardness measurement test at high temperatures. This is what the present inventors discovered.

The surface structure of the tip of the tuyere according to the present invention has a shear strength of approximately 55 kg/ ^mm2 , which is a high mechanical adhesion strength that could not be obtained with conventional technology. After repeating the thermal cycle up to 40 times, in which the temperature is raised to 500℃ in 20 minutes, held for 10 minutes, and cooled to room temperature in 5 minutes, no cracks were observed and it has excellent peeling resistance. I found out something. In the coating layer cross-sectional hardness measurement test, a stable hardened build-up layer with a hardness of about 700 bits was obtained, and in the coating layer surface hardness measurement test under high temperature, it was 800 bits.
It was found that even at high temperatures of approximately 400°C, it has extremely excellent wear resistance without the extreme hardness reduction seen in conventional technology.

(Example) According to the results of an actual furnace test of a tuyere having a surface structure according to the present invention, no damage such as melting was observed after about one year of use, and the wear of the tip was about 1 mm (with a build-up thickness of 6.5 mm).
mm). Furthermore, there was no decrease in hardness due to long-term use. As described above, according to the present invention, it is possible to significantly extend the life of the tuyere, which could only last about one year with the conventional technology.

(Effects of the invention) As described above, according to the invention, the tuyere tip surface structure has high mechanical strength and excellent abrasion and abrasion resistance for areas that are subject to severe wear and erosion, such as blast furnace blast tuyeres. can be obtained, resulting in extremely excellent industrial effects.

[Brief explanation of the drawing]

The drawing is a cross-sectional view of the tuyere structure of the present invention. 1...Tuyere body, 2...Cooling water circulation path, 3...
Nickel-based welding layer, 4...Titanium carbide welding layer.

Claims (1)

[Scope of utility model registration request] Abrasion resistant under high temperature, characterized by forming a welding layer made of nickel base on the tip surface of the tuyere body made of copper casting, and further forming a welding layer made of titanium carbide on the welded layer. Tuyere with excellent peeling resistance.