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Technique for producing precision castings of zirconium and zirconium alloy pumps/valves

A technology of precision castings and process methods, which is applied in the field of precision castings for valves and the production of zirconium and zirconium alloy pumps to achieve stable performance, less internal defects, and normal use.

Inactive Publication Date: 2011-09-28
SHENYANG NORTH TITANIUM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the defects of the prior art, and propose a molding technology using investment ceramic shell casting, which can significantly improve the surface finish of the casting, and at the same time realize near-net molding to avoid material waste and internal defects of the casting. also decreased

Method used

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  • Technique for producing precision castings of zirconium and zirconium alloy pumps/valves

Examples

Experimental program
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Effect test

preparation example Construction

[0017] 4. Preparation of ceramic moulds: Firstly, wax is taken into the mold with a wax injection machine (process requirements: pressure 0.2-1 MPa, pressure holding time 2-6 minutes); the wax type is coated, sanded, Drying and waxing process to make ceramic type;

[0018] 5. Casting: Put the ceramic type and spare electrode into the vacuum shell solidification furnace, and pour (process requirements: vacuum degree <0.01 Pa, melting current 14000-26000A, time 4-15min);

[0019] 6. Hot isostatic pressing: Hot isostatic pressing of castings (process requirements: temperature 900-1260 degrees Celsius, pressure 100-160 MPa, holding time 0.5-2h);

[0020] 7. Refurbishment and sandblasting: repair and sandblast the casting after hot isostatic pressing (process requirements: spray pressure 0.05-0.4 MPa, nozzle diameter Ф25-Ф70);

[0021] 8. Heat treatment: heat treatment after sandblasting (process requirements: temperature 500-600 degrees Celsius, holding time 0.5-2h, cooling metho...

Embodiment 1

[0024] Alloy pump, the alloy is composed of the following chemical components by weight percentage: Zr+Hf~99.2, Fe+Cr~0.20, H~0.005, N~0.025, C~0.05, 0~0.14, the impurities contained in the alloy meet the standards performance requirements. Each chemical composition is made into an alloy by the traditional alloy preparation process, that is, Zr702 alloy. According to the process shown in the figure, the alloy casting data prepared according to the weight ratio of the above chemical composition are as follows:

[0025] Dimensional accuracy of castings: ≤±0.1%;

[0026] Internal quality of castings: no cracks and inclusions, no continuous distribution of porosity and pores,

[0027] Individual porosity and pore size: ≤0.5mm;

[0028] Mechanical properties of castings:

[0029] σ b ≥483MPa, σ 0.2 ≥342MPa, δ 5 ≥12%

Embodiment 2

[0031] Alloy valve, the alloy is composed of the following chemical components by weight percentage: Zr+Hf~99.4, Fe+Cr~0.19, H~0.005, N~0.024, C~0.05, O~0.15, and the impurities contained in the alloy meet the standards performance requirements. The chemical components are made into an alloy by traditional alloy preparation process, that is, Zr702 alloy, which can be used in the production of various common valve casting equipment.

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Abstract

The invention provides a technique for producing precision castings of zirconium pump and valves. The technique is characterized in that the precision castings of zirconium pumps and valves are produced by adopting the methods of lost-wax ceramic-shell precision casting and hot isostatic pressing, wherein the lost-wax ceramic-shell precision casting refers to near-net-shape casting adopting a lost-wax ceramic shell for casting in a vacuum self-consuming skull furnace; the lost-wax ceramic shell is formed through reproduction according to a wax pattern consistent with the geometric shape and size of a pump and valve component; the first two layers of the shell of the inner surface of the lost-wax ceramic shell is made from special oxide; the whole shell is manufactured through the process links of wax pressing, painting, shell hanging, dewaxing, roasting and the like; and the hot isostatic pressing is to place a to-be-treated casting in a container which ishermetic and resistant to high pressure and can be heated to high temperature, vacuumize the container, fill the container with high-pressure inert gas and heat the container to a preset temperature. The technique has the advantage of solving the problem of low material utilization rate and hidden trouble caused by no welding seams at high temperature and high isostatic pressure in all directions, high surface finish of the casting, few internal defects of the casting, pure composition and stable performance.

Description

technical field [0001] The invention relates to a precision casting of zirconium and zirconium alloy pumps and valves for chemical industry, in particular to a process for producing precision castings of zirconium and zirconium alloy pumps and valves. Background technique [0002] At present, the manufacturing technologies of zirconium and zirconium alloy pumps and valves mainly include forging cutting processing + welding forming and casting forming. The production of zirconium and zirconium alloy pump valves mostly adopts forging cutting processing + welding forming technology. However, this method has a low material utilization rate due to a large amount of material cutting, and the cost is too high due to the high price of zirconium and zirconium alloy materials. At the same time, the existence of weld seams greatly increases the hidden dangers in the use of pump valves. Therefore, the development of zirconium and zirconium alloy pump valve casting molding technology ha...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22C9/04
Inventor 王铁张建伟陈博桓甘冬梅杨志新梁迪马帆
Owner SHENYANG NORTH TITANIUM IND
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