Grain Refinement of Aluminum Alloy Bar by a Modified RAP Process for Semi-Solid Forming

Abstract

A modi ed Recrystallization and Partial Melting (RAP) process including Radial Forging (RF) and Semi-Solid Isothermal Treatment (SSIT) was proposed to re ne the grains of 6063 Al alloy bar for semi-solid forming. The 6063 Al alloy bar (φ120 mm × 800 mm) was deformed by RF into a stepped shaft with different Area Reduction Ratios (ARRs) at the temperature of 300 C, and then the samples cut from both the central and peripheral parts of the RF-deformed bar were treated with SSIT at 630 C for 10 min. The effect of ARR on the microstructural evolution of semi-solid 6063 Al alloy was investigated. Results showed that, during the RF process, the microstructures of the samples became denser as the ARR increased. After SSIT, with the increase of ARR, the average grain sizes of both the central and peripheral parts were reduced and the spheroidization degrees of both the central and peripheral parts were improved. The variation tendency of grain size experienced three different stages: precipitous reduction, gentle reduction and unobvious change. Besides, the differences between grain sizes of the peripheral and central parts were gradually decreased with the increase of ARR. Additionally, the optimal process parameter for re ning grains was 70% ARR at 630 C for 10 min.

Experimental Investigation and Optimization of the Semisolid Multicavity Squeeze Casting Process for Wrought Aluminum Alloy Scroll

“…These samples were located at the inner gate (Position A1), the central region of the scroll (Position A2), and the bottom region of the scroll (Position A3), as shown in Figure 4 . The microstructure of the samples was observed by an optical microscope (NIKON ECLIPSE LV 150N, Nikon, Tokyo, Japan) from 10 different fields of view for each sample, based on which the average grain diameter and shape factor of the metallographic structure were firstly measured using the Image-Pro Plus 6.0 software (Media Cybernetics, Rockville, MD, USA) and quantitatively analyzed by Equations (1) and (2) [ 32 ], respectively. Samples from the central region of the scroll (Position A2) were used for testing the mechanical properties by using a universal materials tester (INSTRON 5982, Instron, Norfolk, MA, USA) and a hardness tester (HV-1000, Shanghai Shangcai Testermachine Co.,Ltd, Shanghai, China).…”

Research Progress on the Manufacturing of Screw-Shaped Parts in Screw Compressors

“…During the SSMF process, the semi-solid materials are first prepared with grains of significantly small sizes and spherical shapes. Then, the complex parts with fine microstructures and excellent performance can be produced by extrusion, forging, rolling or die casting processes [65,66]. SSMF has the advantages of high flowability in casting combined with the excellent mechanical properties of components processed by solid plastic forming.…”

Numerical Simulation and Experimental Investigation of the Preparation of Aluminium Alloy 2A50 Semi-Solid Billet by Electromagnetic Stirring

“…In each field of view, the area and perimeter of the crystal grains were measures at more than 5 different positions. The average size of grains (D) and shape factor (F) were calculated by Equations ( 10) and ( 11) [25][26][27] based on the number, areas, and perimeters of all solid grains in the sample obtained by using the Image-Pro Plus 6.0 software. The average diameter is the average value of the equivalent diameter of all grains.…”