Aluminum Alloy Melting Temperature and Holding Time: Key Factors in Aluminum Extrusion Quality

Aluminum alloy melting temperature and holding time are important factors affecting billet quality and the subsequent aluminum extrusion process. Proper control of these parameters helps reduce oxidation, gas absorption, coarse grain formation, and cracking, providing a better foundation for producing high-quality aluminum profiles with an aluminum extrusion press.

Controlling Aluminum Alloy Melting Temperature

Higher melting temperatures can promote alloying and improve the dissolution of alloying elements. However, excessive temperatures increase the risk of oxidation and hydrogen absorption, potentially leading to casting defects and coarse-grained billet structures.

In general, the melting temperature of wrought aluminum alloys is controlled at approximately 50–100°C above the alloy liquidus temperature. For alloys such as 3A21, 2A70, and 2A80, which have a greater tendency to form primary intermetallic compounds, melting temperatures of 720–760°C may be used to support adequate dissolution of alloying elements. For eutectic 4xxx-series alloys, when silicon is added in the form of master alloys or crystalline silicon, a temperature range of 750–780°C may be appropriate. Other alloys are generally melted at 700–750°C, depending on their composition and process requirements.

These ranges are general process references. Actual temperatures should follow the alloy specification and validated production procedures.

Why Melting and Holding Time Matter

Excessively long melting and holding times can increase oxidation, gas absorption, melt contamination, and composition variation. They may also reduce furnace productivity and affect grain structure and casting quality. After refining, prolonged holding can weaken the effectiveness of modification treatments.

As a general principle, melting and holding time should be kept as short as practical while allowing sufficient time for melting, refining, sampling, and composition adjustment. If the specified holding time is exceeded, additional refining, stirring, and sampling may be required. For certain alloys, composition correction or approved grain-refining additions may also be considered.

From Billet Quality to Aluminum Extrusion Performance

For aluminum profile manufacturers, billet quality directly influences extrusion consistency, surface finish, and the risk of defects during forming. Huanan Heavy Industry Technology Co., Ltd. manufactures aluminum extrusion presses designed for industrial profile production. Combining suitable billet preparation with appropriate extrusion force, speed control, and process settings helps manufacturers establish a more controlled production process for different aluminum profile applications.