A kind of brass alloy grain refiner and its preparation process and application method

Abstract

The invention provides a brass alloy grain refiner and a preparation technology and a using method thereof, and belongs to the technical field of processing of copper and copper alloys. The brass alloy grain refiner comprises the following components in parts by mass: 5-20 parts of iron-silicon alloy, 80-92 parts of KBF4, 1-5 parts of carbonate, and 3.5-6 parts of manganese. The brass alloy grainrefiner can improve the flowability of a brass alloy melt and reduce macroscopic casting defects on the premise of ensuring the refining effect; the condition that a high-melting-point material phaseis remained in a cast ingot is avoided, the smooth development of the follow-up manufacturing procedure of a brass product is facilitated, and the product surface quality is improved; the melt treatment process control is simplified, and the production cost is reduced; the addition of elements such as Ti, Zr and B is reduced or avoided, other alloy elements are selected to form an effective nucleation core, the poisoning failure phenomenon of refining elements is avoided, and the grain refining longevity is improved.

Description

technical field [0001] The invention belongs to the technical field of copper and copper alloy processing, and in particular relates to a brass alloy grain refiner and its preparation process and use method. Background technique [0002] According to the characteristics of the molding process, brass can be divided into cast brass and deformed brass; according to the type of matrix structure, it can be divided into single-phase brass and dual-phase brass. In actual production, the refinement of the as-cast crystal structure is an effective internal guarantee for the smooth development of various subsequent processing procedures for this type of material. Taking ordinary brass (H65) as an example, the alloy material tends to have coarse grains and a large proportion of columnar grains in the continuous casting process, resulting in a decrease in the plasticity of the material, difficulty in extrusion, and easy cracking during thermal processing ( That is, the tendency of "hot...

AI Technical Summary

Problems solved by technology

The obvious shortcomings of this refiner are: (1) Multiple components are added to the high-temperature brass melt in the form of aluminum-based master alloy, which is easy to produce Al 2 o 3 , which increases the difficulty of impurity removal; (2) There is a large proportion of Al-Sr master alloy, which is easy to cause gas absorption during the brass alloy melting and casting process, resulting in the ingot structure not being dense; (3) Adding high melting point directly in the form of fine particles Zr metal (1852°C), it is difficult to ensure the solid solution effect of Zr in copper melt, and the fine Zr powder can also strongly absorb nitrogen, hydrogen, oxygen and other gases, which is very easy to burn, and sometimes it can spontaneously ignite and explode, except In addition to bringing safety hazards to storage and use, it also directly leads to a large amount of oxidation and burning; (4) The preparation process is complicated and consumes a lot of energy. For the master alloy, in addition to going through the vacuum melting and casting process, it must also be broken into pieces by machining. Crumbs

[0009] Disadvantage 1 of the prior art: It is mixed with a variety of master alloys or salts containing specific elements, and the main refining elements usually added are Ti, Zr, B, etc.

In addition, these active elements will also segregate and be enriched at the front of the solid / liquid interface, resulting in supercooling of the components, promoting the branching and refinement of the crystal structure, and the segregation at the front of the dendrite growth also prevents its growth.

However, with the prolongation of the holding time, on the one hand, the particles of heterogeneous particulate compounds will accumulate and grow, becoming inclusions and losing the non-spontaneous nucleation; on the other hand, the metamorphic elements such as TiB 2 , AlB 2 、Cu 2 Ti, ZrAl 3 、TiAl 3 With the prolongation of the holding time, the compound will dissolve or precipitate, the number of effective crystal nuclei will decrease, the refinement effect will decrease, causing the deterioration effect to decline, and the structure will be coarse, which is not conducive to long-term casting production (such as more than 90min)

The melting points of the above-mentioned compound phases and some salts in the refiner are higher than that of the brass alloy melt, and they are often non-conductive or poorly conductive. If they remain in the ingot, hard point phases are easily formed directly, resulting in a polished surface. Poor or plating pitting, reducing the appearance quality of brass casting products

In addition, pure salts are used as grain refiners, which are prone to moisture absorption during storage, which affects the refinement effect

[0010] Shortcoming 2 of the prior art: In order to improve the long-term effect of crystal structure refinement, some existing high-efficiency brass alloy refiners often add an appropriate amount of rare earth elements (usually the master alloy Cu-RE or Al-RE )

However, the above-mentioned particles are difficult to disperse in the copper liquid, resulting in uneven grain size distribution, and it is easy to make the copper liquid become viscous and fluidity deteriorates, resulting in improper casting, pits, shrinkage, and shrinkage heat during casting. Macro defects such as cracks

In addition, due to the deterioration of melt flow performance, high temperature is required in the melting and casting process, which is easy to accelerate the failure of other effective refinement elements and waste energy, and if the nucleation particles produced under the action of rare earth remain in the ingot, it is still easy to form incomplete Conductive impurity points (agglomeration), affecting the apparent quality of castings

The above-mentioned problems that may occur when adding rare earth elements are also directly related to the amount of addition, and it is often difficult to control

Of course, the price of rare earth refiners is also generally higher

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