Materials used in heat treatment, such as aluminum, zinc,copper alloys, and steel, are treated to improve strength and durability.

The process of die casting always involves subjecting the casting to mechanical stress to obtain refined properties and increased durability.

In order to improve the die’s impact resistance and intergranular cracking along with maintaining its structural integrity, alloys undergo a series of hot working cycles followed by annealing and claim processes.

Corrosion infiltration treatment and wet etch process is done to boost aluminum’s rigidity enhancing properties.

Ceramics and other non metals can also be subjected to certain thermal processes such as coating the surface of a component with ceramic for improved wear tolerance.

This is an integral process when the specific material design requires distinct details or tailored attributes, especially when considering the thermal effects on the materials microstructure.

Materials used in heat treatment

The table below depicts the materials used in combination with the desired techniques for die casting and corresponding heat treatments.

• Aluminum Alloys
• Zinc Alloys
• Magnesium Alloys
• Copper Alloys
• Steel

Aluminum Alloys

Aluminium die cast alloys are frequently used alloys in die casting due to their lightweight nature and high strength. Heat treatment of aluminium alloys consists of processes such as solution heat treatment which involves dissolving alloying elements and artificial aging which increases strength.

Zinc Alloys

Zinc alloys are also utilized in die casting owing to their good mechanical properties in addition to exceptional castability. Heat treatment of zinc alloys routinely involves aging, which greatly enhances strength and hardness.

Magnesium Alloys

Magnesium alloys are chosen owing to their low density but experience high strength per unit weight. Heat treatment of magnesium alloys often includes solutions and aging processes which improve the mechanical properties of the alloy.

Copper Alloys

Copper alloys like brass and bronze have enormous strength and corrosion resistance. And is used in die casting because of their superb thermal and electric conductivity. Treatment of copper alloys under elevated temperatures may include to soften the material. Thereby improving the formability to increase the alloy ductility.

Steel

Steel is used in die casting as it posses high strength and wear resistance. The heat treatment processes for steel include normalizing, annealing, quenching and tempering which is done to obtain a certain strength and toughness and controlled hardness.

Importance of Heat Treatment of Die Casting Components

Castings tend to have lower mechanical properties like strength, hardness, and even toughness. To remedy this issue, heat treatment is indispensably critical in the die casting process. This becomes more important in components that endure substantial mechanical stress and wear during their service life.

A more handy example would be the automotive industry where numerous. And complex engine parts are first manufactured by die casting. And are subsequently heat treated as they require high levels of reliability and performance.

A set of advanced die casting machines was supplied by Haichen in 2020 to one of the Thailand based companies in the automotive industry. This company primarily deals with the manufacturing of high precision Automotive engine cylinder blocks and cylinder heads. Which, during operation, requires the component to sustain severe levels of temperature and pressure. The application of die casting machines from Haichen has enabled this company to automate. And refine process control with guaranteed quality of the castings. Further value added processes through heat treatment is part of the production process to increase the mechanical properties further for compliance with automobile engine requirements.

This fully incorporates the significant impact that heat treatment of die casted components has. And the exemplary performance of the Haichen die casting machines during the operations.

Selection of heat-treated materials

Different materials have different properties and react differently to heat treatment processes. Therefore, it is important to select the material that best suits the application requirements.

Take for instance high carbon steel. It is the most common material for making railway spikes because of the need for extreme hardness and wear resistance. Spikes must endure high stress and frequent friction during use. Therefore a great deal of quenching and tempering to increase hardness and wear resistance is done after functionalizing the dies.

Something like the housing of outdoor lighting fixtures requires the panels to be lightweight and corrosion resistant. Thus aluminum alloys are used. Having lesser weight, aluminum alloys can have their strength. As well as corrosion resistance enhanced if proper heat treatment like solution treatment or aging hardening is done, making them suitable for outdoor products.

Zinc Alloys Expansion: HAICHEN Medal Production Case

Zinc alloys have good fluidity and excellent electroplating properties, widely used in decorative castings such as medals and badges. Heat treatment (aging) further improves the hardness and dimensional stability of zinc alloys, preventing thin-wall parts from deforming during storage or transportation.

HAICHEN Medal Production Case

A souvenir manufacturer uses a HAICHEN HCD90 hot chamber die casting machine to produce zinc alloy medals. Product diameter is 65mm, thickness 3mm, with raised text and patterns on the back.

Challenge: The medals are thin and showed slight warping after ejection, affecting electroplating flatness. Some products experienced minor dimensional changes during storage, causing unstable plating adhesion.

HAICHEN Solution:

• Use Zamak 3 zinc alloy, casting temperature 420℃, injection pressure 12MPa, two-cavity mold, cycle time 22 seconds
• Artificial aging after ejection: hold at 100℃ for 4 hours, then cool naturally
• Straightening treatment after aging to eliminate residual stress

Results:

• Hardness increased from 85HB to 95HB after aging
• Dimensional change less than 0.02% after three months storage, meeting plating flatness requirements
• Electroplating yield increased from 91% to 98%, annual output reached 1.5 million pieces

This case shows that proper aging treatment significantly improves dimensional stability of thin-wall zinc alloy parts, providing a good base for subsequent surface treatment.

Pan Handle Material Case Expansion

Pan handles are important components in cookware, requiring strength, heat resistance, anti-scald properties, and good appearance. Heat treatment processes vary significantly for different handle materials.

Aluminum Alloy Pan Handle

A cookware company produces die-cast aluminum pan handles using A380 aluminum alloy. Product length is 180mm with uneven wall thickness (handle part 4mm, connection part 8mm).

Challenge: The thicker connection part had residual stress after natural cooling, occasionally causing micro-cracks after machining. The handle part needed sufficient strength to avoid deformation during use.

HAICHEN Solution:

• Use HAICHEN HDC280 cold chamber machine, injection pressure 80MPa, temperature 660℃, cycle time 55 seconds
• T5 heat treatment: artificial aging at 185℃ for 4 hours
• Hardness increased from 75HB to 95HB, tensile strength from 240MPa to 290MPa after aging

Results:

• Residual stress eliminated, machining cracks resolved
• Handles passed strength tests, meeting cookware safety standards
• Uniform anodizing finish with good color consistency

Haichen’s Role in Die Casting Heat Treatment

At Haichen, we focus on the manufacturing of advanced die-casting machines designed to suit the needs of every client’s requirement of heat treating differing materials. We provide our machines with the capability of precise temperature control and unmachined uniform distribution of heating. These factors are fundamental to achieving the required mechanical properties of aluminum, zinc, and other alloys.

Advances in Technology Integration

Haichen automates the die casting solutions, implements advanced technologies, which streamlines the processes and cuts down the costs.

This enhances the heat treatment procedure alongside the quality and reliability of the final products.

Maximal Optimal Outcomes Obtained Using Heat Treatment

Haichen guarantees optimal heat treatment for the machines, making them desirable to manufacturers who aim to refine their heat treatment processes.

Equipped with Haichen technology, manufacturers can obtain far better results concerning the components which need to undergo precise thermal treatment during production.

HAICHEN’s Real-World Application Case

A die-casting manufacturer producing large aluminum alloy structural parts for the automotive industry faced a significant challenge when using HAICHEN’s 880-ton cold chamber die-casting machine: the core mold inserts (especially the core and sliders) used to form complex thin-walled structures began to show early signs of thermal fatigue cracking and slight plastic deformation after approximately 15,000 cycles of production. This led to increased burrs and dimensional deviations in the castings, and frequent mold repairs severely disrupted production schedules and increased costs.

HAICHEN’s Solution

After analysis, the HAICHEN technical team determined that the root cause of the problem was that the heat treatment process of the mold material did not fully match the characteristics of the high-cycle thermal load of the part. The customer’s original mold used general-purpose H13 (4Cr5MoSiV1) hot work tool steel, but its toughness and thermal stability after heat treatment were insufficient.

Material Upgrade Recommendation

HAICHEN recommended upgrading the critical inserts subjected to the highest impact and thermal loads to high-quality pre-hardened H13 steel, or using high-end materials with higher thermal fatigue resistance such as Dievar (from Uddeholm, Sweden) or HD (an improved domestic version). These materials, through purer metallurgical processes and micro-alloying, significantly improve toughness, thermal conductivity, and resistance to tempering softening while maintaining high hardness.

Application Results

After implementing the material and heat treatment optimization, the service life of the critical mold inserts was significantly improved.Under the same HAICHEN die-casting machine and production parameters, the service life of the mold inserts was significantly extended. They reached over 35,000 production cycles before showing signs of thermal fatigue requiring maintenance. This represents a lifespan increase of more than 130%.

Concurrently, issues related to casting dimensional fluctuations and burrs caused by mold deformation were substantially reduced. This improvement ensured higher production stability and overall yield.

As a result, the mold cost allocated to each unit product was effectively lowered for the customer. This outcome clearly demonstrates the core value of applying precise materials science and heat treatment processes in high-end die-casting production.

A certain set of materials is chosen in regard to the properties which are expected from a die casting heat treatment part.

The materials like: aluminum, zinc, magnesium, and copper alloyed steel, including other steels are selected in regard to their thermal processing capabilities.

Each material is subjected to a unique heat treatment process and the aim is to provide the right amount of strength, ductility, and stability to the geometry of the component.