Effect of Rolling Treatment on Microstructure, Mechanical Properties, and Corrosion Properties of WE43 Alloy

Abstract

Magnesium alloys show broad application prospects as biodegradable implanting materials due to their good biocompatibility, mechanical compatibility, and degradability. However, the influence mechanism of microstructure evolution during forming on the mechanical properties and corrosion resistance of the magnesium alloy process is not clear. Here, the effects of rolling deformation, such as cold rolling, warm rolling, and hot rolling, on the microstructure, mechanical properties, and corrosion resistance of the WE43 magnesium alloy were systematically studied. After rolling treatment, the grains of the alloy were significantly refined. Moreover, the crystal plane texture strength and basal plane density decreased first and then increased with the increase in rolling temperature. Compared with the as-cast alloy, the strength of the alloy after rolling was significantly improved. Among them, the warm-rolled alloy exhibited the best mechanical properties, with a tensile strength of 346.7 MPa and an elongation of 8.9%. The electrochemical experiments and immersion test showed that the hot working process can greatly improve the corrosion resistance of the WE43 alloy. The hot-rolled alloy had the best corrosion resistance, and its corrosion resistance rate was 0.1556 ± 0.18 mm/year.

Keywords: WE43 magnesium alloy; corrosion properties; grain size; mechanical properties; rolling.

Figure 1

Schematic diagram of the three processing routes.

Figure 2

XRD patterns of WE43 in as-cast, cold-rolled, warm-rolled, and hot-rolled condition.

Figure 3

The SEM images of WE43 in (a) as-cast, (b) cold-rolled, (c) warm-rolled, and (d) hot-rolled condition.

Figure 4

The IPF maps in the RD-SD plane (distribution of crystallographic direction parallel to CD) showing the microstructures of the WE43 alloy after rolling. (a) Cold-rolled, (b) warm-rolled, and (c) hot-rolled, and (d) distribution map of different rolled grain sizes. (e) Basal (0001) recalculated pole figures of the WE43 alloy.

Figure 5

Mechanical properties of as-cast, CR, WR, and HR samples of WE43 alloy: (a) tensile stress–strain curves (b) yield strength, ultimate tensile strength, elongation, and hardness.

Figure 6

Fracture morphology of WE43 magnesium alloy under tension at room temperature in different states: (a) as-cast, (b) cold-rolled, (c) warm-rolled, and (d) hot-rolled.

Figure 7

Electrochemical performance of WE43 magnesium alloy in Hanks’ solution. (a) Open circuit potential,, (b) potentiodynamic polarization curves, (c) bode plots, and (d) Nyquist plots and equivalent circuits.

Figure 8

Variation in solution pH of the magnesium alloys with different states during 7 days of immersion in Hank’s solution and the corresponding corrosion rate obtained by weight loss.

Figure 9

XRD pattern: (a) energy spectrum analysis (b) and energy spectrum map of the surface corrosion products on WE43 alloy after immersion for 7 days in Hanks’ solution.

Figure 10

The SEM morphologies of the surface corrosion products on WE43 alloy after immersion for 7 days in Hanks’ solution: (a) as-cast, (b) cold-rolled, (c) warm-rolled, and (d) hot-rolled.