Ball grinding-diameter shrinkage reciprocating extruding method for circular curing of waste titanium chips

Abstract

The invention proposes a ball grinding-diameter shrinkage reciprocating extruding method for circular curing of waste titanium chips. The method comprises the following steps: (1) the titanium chips are recovered and preheated; (2) the ball grinding is performed for the titanium chips; (3) the titanium chips are covered and packed; (4) the covered and packed titanium chips are coldly extruded at room temperature; (5) diameter shrinkage reciprocating extrusion high-temperature curing: a mold is heated to reach 570-600 DEG C; an upper punch applies the extruding force of 0.9-1.0 GPa; a lower punch applies the back pressure of -200 MPa; in the same pair of reciprocating extrusion molds, the room-temperature cold extruded titanium chips perform the diameter shrinkage extrusion, the ejection, the compression upsetting and the secondary diameter shrinkage extrusion deformation; and (6) quenching: massive titanium obtained in the diameter shrinkage reciprocating extrusion step is quenched and cooled to reach the room temperature through a water cooling mode. Through ball milling, oxides on the surfaces of the chips are totally crushed under collision and grinding of steel balls; and on the basis, the high-temperature extrusion curing is performed to cure the titanium chips as large-size massive titanium.

Description

technical field [0001] The invention relates to a metal material processing method, in particular to a ball milling-diameter-shrinking reciprocating extrusion method in which waste titanium chips are cyclically solidified. Background technique [0002] Titanium is a metal resource with high smelting costs. It has excellent biocompatibility, good corrosion resistance, and suitable mechanical properties. It is an important material for manufacturing medical devices, artificial joints, and large energy and chemical containers. However, in order to manufacture high-precision Ti structures, a large machining allowance needs to be designed, and a large amount of raw materials will be converted into waste chips. The traditional high-temperature melting and casting process has high energy consumption, heavy pollution, low efficiency, and the casting structure has coarse grains and poor performance. Solid phase recycling and remanufacturing is an effective way to achieve efficient a...

AI Technical Summary

Problems solved by technology

However, titanium (Ti) is an active metal that is easy to oxidize, and the oxide on the chip surface is TiO 2 Although the oxides can be broken and dispersed to a certain extent after multi-pass ECAP treatment, the continuous distribution of larger oxides will form metallurgical defects in the microstructure and weaken the mechanical properties of the material

There is also a refinement limit in ECAP processing, that is, when the dynamic recrystallization and strain refinement effects are balanced, it will be difficult for ECAP to further refine the microstructure to nanoscale

Moreover, under the condition of a 90-degree rotation angle, the equivalent strain produced by ECAP single-pass processing is about 1. In order to accumulate strain, it must be repeatedly extruded in multiple passes, so the strain accumulation rate of ECAP needs to be improved.

At the same time, after the powder is processed by BM, subsequent processing processes such as hot pressing sintering or powder extrusion / forging are required to obtain bulk materials. In these processes, due to factors such as long heating (sintering) time and dynamic recrystallization, Grain coarsening will occur, weakening the strength of the material

Moreover, the processing efficiency of traditional hot extrusion technology still needs to be improved

The above technical problems have not been well resolved

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