Squeeze casting preparation technology of AZ91D rare earth magnesium alloy

Abstract

The invention discloses a squeeze casting preparation technology of AZ91D rare earth magnesium alloy. The technology solves the problem that the mechanical property of magnesium alloy is affected due to the fact that air holes emerge easily and die-casting of special-shaped castings is hard and cost is high in an existing preparation process of a basic phase of the magnesium alloy. The technology comprises the steps of placing AZ91D magnesium alloy in a resistance furnace, heating the resistance furnace till the temperature reaches to 180-220 DEG C, and keeping the temperature for 20 min; continuing to heat the resistance furnace till the temperature reaches to 400 DEG C and adding mixed gas of air, carbon dioxide and tetrafluoroethane with a volume ratio of 74:25:1; continuing to heat the resistance furnace till the temperature reaches to 760-800 DEG C, adding preheated Mg - 25% Y intermediate alloy, and stirring evenly with a graphite rod after the Mg - 25% Y intermediate alloy is melted, wherein the mass fraction of the Mg - 25% Y intermediate alloy in the magnesium alloy is 6-10%; carrying out filtering by spin-spraying Ar air and combining with MgO foamed ceramics, and carrying out compound purification on magnesium solution for 30 min; and cooling the resistance furnace till the temperature reaches to 715-725 DEG C, pouring the metal solution into a preheated die, extruding the blank out and cutting the blank, carrying out T4 heat treatment on the blank, wherein the preheating temperature of the die is 200-250 DEG C, the extruding force is 95-105 MPa, and the dwell time is 20-25 s. The squeeze casting preparation technology of the AZ91D rare earth magnesium alloy has the advantages that processes are simplified, usage is achievable with no need for deep processing, raw material is saved, and cost is reduced.

Description

technical field [0001] The invention relates to a preparation process of a magnesium alloy, in particular to a squeeze casting preparation process of an AZ91D rare earth magnesium alloy. Background technique [0002] At present, magnesium alloy castings on the market are formed by die casting, and their mechanical properties are poor. The essence of pressure casting (referred to as die casting) is to make liquid or semi-solid metal liquid fill the die casting cavity at a high speed under high pressure, and form and solidify under pressure to obtain castings. High-pressure and high-speed filling die-casting molds are two major characteristics of die-casting. The injection specific pressure is usually several MPa to tens of MPa, the filling speed is about 10-50m / s, and the filling time is very short, generally in the range of 0.01-0.2s. Due to the fast filling speed of molten metal and unstable fluid state in general die-casting methods, the castings are prone to produce por...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the basic phase of the existing magnesium alloy and the problems that pores are easily generated during the preparation process, the difficulty of die-casting special-shaped castings and the high cost affect the mechanical properties of the magnesium alloy, the invention provides a extrusion casting preparation process of the AZ91D rare earth magnesium alloy