Semi-solid Rolling Research Articles

Effect of the casting temperature on temperature field and microstructure of A2017 alloy during an innovative continuous semisolid rolling process with a vibrating sloping plate device

In this paper, the effect of temperature field on microstructure of A2017 alloy during an innovative continuous semisolid rolling process with a vibrating sloping plate device was studied. The results show that the alloy temperature decreases gradually from the entrance to the exit of the roll gap. In the backward slip zone, the isothermal lines have twice buckling. In the forward slip zone, the isothermal lines have once buckling. Semisolid region moves forward from the filling mouth to the exit of the roll gap with the increment of casting temperature, and the solid fraction increases from the entrance to the exit of the roll gap. The average grain size of the product increases with the increment of casting temperature, and the plastic deformation along the rolling direction happened obviously. According to the simulation and experiment, the proper casting temperature between 650 and 680 °C is suggested. A2017 alloy strip with good surface quality was obtained. The microstructure of the product is mainly composed of fine spherical or rosette grains which were elongated along rolling direction.

Casting of Aluminum Alloy Bar by Semisolid Roll Casting

Rheo-casting of 4045 aluminum alloy bar was operated using an unequal diameter twin roll caster and a cooling slope. The semisolid slurry was made by the cooling slope. The thickness of the bar was 12 mm and width was 100mm. The casting speed was 1m/min. Quantity of the melt poured on the cooling slope was important to make sound bar. The primary crystal became spherical, and its size was about 40μm.

Semi-solid rolling process of steel strips

Abstract Semi-solid metal forming (SSF) is recognized as a new forming technology, which has been paid more and more attention by the researchers all over the world. The semi-solid rolling process (Rheo-rolling) combines the fabrication of slurry with continuously rolling as an important neoteric means to achieve near-shape forming. In this paper, an original device of semi-solid rolling has been designed and manufactured to prepare the spring steel–60Si2Mn and stainless steel–1Cr18Ni9Ti. The semi-solid slurry is successfully fabricated by electromagnetic stirring and rolled into the strips with the thickness of 3–5 mm, the width of 70 mm and the length of 1000 mm. The effects of the stirring parameters, including stirring power and time, on the solid fraction and microstructure of steel, have been investigated through electromagnetic stirring process. The experimental results show that the semi-solid slurry with the solid phase diameter of 50–150 μm and the solid fraction (fs) of 5–65% can be obtained by electromagnetic stirring. The highest ultimate tensile strength and elongation obtained for 60Si2Mn strip with 60% solid fraction are 860 MPa and 13.4%, respectively. For 1Cr18Ni9Ti strip with 60% solid fraction, the highest ultimate tensile strength and elongation are 1022 MPa and 40.6%, respectively. With increasing the solid fraction, the properties of semi-solid rolled products become better. The method of grooved rolling can ameliorate the stress state at the edge of rolled strip, which is beneficial to improve the homogenization of microstructure.

Semisolid Roll Casting of Aluminum Alloy Strip and Its Properties

A356 was cast into the strip by the semisolid strip casting using an unequal diameter twin roll caster. This process was one of the rheocasting. The semisolid slurry was made by a cooling slope. Solid fraction was about 5%. The casting speed was 20 m/min, and the thickness was 4.4 mm. The as-cast strip could be cold rolled down to 1 mm. The result of tension test of 1mm-thickness-T4 heat-treated strip was as below. Tensile stress was 223 MPa, 0.2 proof stress was 123 MPa and elongation was 21.8%. Deep drawing could be operated to 1 mm-thickness T4 sheet, and L.D.R was attained to 2.0. In some condition, 180 degrees bending could be operated without crack at outer surface. These results mean that semisolid roll cast A356 strip may be able to use for press forming.

Warm deep drawing of wrought magnesium alloy sheets produced by semi-solid roll strip-casting process

This paper is concerned with the development of a continuous strip-casting technology to facilitate the manufacture of magnesium sheet alloys economically whilst maintaining high quality. Established in the paper is warm formability of cast magnesium alloy sheets after being hot rolled by semi-solid roll strip-casting process. It has been found that magnesium sheet with 2.0–4.0 mm thickness could be produced at a speed of 25 m/min. Hot rolling and annealing temperatures during hot rolling were also changed to examine which condition would be appropriate for producing wrought magnesium alloys with good formability. Microstructures of the crystals of the manufactured wrought magnesium alloys were observed. It has been found that a limiting drawing ratio of 2.7 was possible in a warm deep-drawing test of the cast magnesium alloy sheets after being hot rolled.

High Speed Roll Casting of Aluminum Alloy Strip

Two kinds of roll casters, which were suitable for high speed roll casting, were devised. One was a vertical type twin roll caster, and the other was an unequal diameter twin roll caster. The semisolid roll casting using a cooling slope was adopted to these roll casters. The solid fraction was smaller than 5%. 3 mm thickness of 6111 strip was cast at 60 m/min by the vertical type twin roll caster, and 5 mm thickness of 6111 strip was cast at 30 m/min by the unequal diameter twin roll caster. The microstructure of the as-cast strip was equiaxed and spherical, not columnar. The mechanical properties of the strip rolled from roll-cast strip were almost as same as that of the strip made from cast ingot.

Semi-solid manufacturing process of magnesium alloys by twin-roll casting

An experimental approach has been employed to ascertain the effectiveness of semi-solid roll strip casting of magnesium alloys by a twin-roll caster. The demand for light-weight products with high strength has grown recently due to the rapid development of automobile and aircraft technology. One key to such development has been utilization of magnesium alloys, which can potentially reduce the total product weight. However, the problems of utilizing magnesium alloys are still mainly related to high manufacturing cost. One of the solutions to this problem is to develop magnesium casting–rolling technology in order to produce magnesium sheet products at competitive cost for commercial applications. In this experiment, magnesium alloys AZ31B, AZ91D, AM50A and AM60B were used for twin-roll strip casting. Temperature of the molten materials and roll speeds of upper and lower rolls, which could be adjusted independently, were varied to find appropriate manufacturing conditions. Effects of cooling and contact condition on possible forming were clarified in terms of contact condition between molten material and the rolls. Microscopic observation of the crystals of the finished casting was performed. It has been found that 2.0–3.0mm thick magnesium sheets could be produced at a speed of 25m/min. It has been found that the hot rolled cast magnesium sheets produced by semi-solid manufacturing process could be used for plastic forming.

Formability of Magnesium Alloy Sheets Manufactured by Semi-Solid Roll Strip Casting

An experimental investigation was performed into the formability of magnesium alloy sheets that were hot-rolled after a semi-solid roll strip casting process. Semi-solid forming helps reduce the total product weight if the semi-solid material produced by light metals, such as aluminum and magnesium can be used to replace conventional iron and steel products. However, the problems of utilizing magnesium alloys are still related to high manufacturing costs. This means that improved quality must be balanced by economic validity. Magnesium alloy AZ31B was used in this experiment to ascertain the effectiveness of semi-solid roll strip casting for producing magnesium alloy sheets. The temperature of the molten magnesium, and the roll speeds of the upper and lower rolls, (which could be changed independently), were varied to find an appropriate manufacturing condition. Rolling conditions and heat treatment were changed to examine which condition would be appropriate for producing wrought magnesium alloys with good formability. Microscopic observation of the crystals of the finished products was performed. It has been found that a limiting drawing ratio of 2.4 was possible in a deep drawing process of the cast magnesium alloy sheets.

Mechanical Properties of Magnesium Alloy Sheets Produced by Semi-Solid Roll Strip Casting

Mechanical Properties of Magnesium Alloy Sheets Produced by Semi-Solid Roll Strip Casting

Semi-solid roll casting of aluminum alloy strip by melt drag twin roll caster

A melt drag twin roll caster (MDTRC) and a melt drag twin roll caster equipped with a cooling slope (MDTRC+CS) was devised in order to increase the casting speed of a strip. These casters are semi-solid strip casters. In the MDTRC, the upper side of the strip is formed by the upper roll at the semi-solid condition. In the MDTRC+CS, the CS cools the melt, which is consequently transformed into semi-solid slurry. The strip is then cast from the semi-solid slurry. The MDTRC and the MDTRC+CS enable Al–6 mass% Si strip to be cast at maximum speed of 60 and 90 m/min, respectively, by applying very small separating forces. The MDTRC and the MDTRC+CS are useful for mushy solidification-type aluminum alloys. A melt drag belt-roll caster (MDBRC) and a melt drag belt-roll caster equipped with a cooling slope (MDBRC+CS) were developed based on the MDRTC in order to cast skin formation solidification-type aluminum alloys at the semi-solid condition into a strip having a sound surface. The MDBRC+CS enables A1050 strip having sound surfaces and a globular microstructure to be cast at a speed of 20 m/min by applying a small separating force.