What Are The Key Differences in Hot And Cold Working Processes For Titanium Alloy Plates?

The processing technology of plates directly determines product precision, mechanical properties, and application adaptability. Hot working and cold working are the two core routes for titanium alloy plate  production. Based on differences in processing temperature and process principles, they form distinct technical characteristics, performance outputs, and application scenarios.

 

 

 

 

Temperature determines the evolution law of the material's internal structure.

 

• Hot working: Plastic forming performed above the recrystallization temperature. Except plastic deformation, the material undergoes dynamic recrystallization, which crushes the as-cast structure. It can form a uniform, fine equiaxed grain structure, eliminates internal defects, and optimizes structural properties.

 

• Cold working: Processing conducted below the recrystallization temperature. The atomic diffusion capacity is weak, and no obvious recrystallization occurs. It can achieve deformation through grain slip and twinning, resulting in work hardening of the material and retention of deformed structural characteristics.

 

 

1. Requirements for Processing Equipment and Environment

• Hot working: Has strict requirements for equipment's high-temperature resistance and load-bearing capacity. High-temperature titanium alloy is easy to react with oxygen, nitrogen, and hydrogen to form brittle compounds. It leads to embrittlement and oxidative scaling. Therefore, processing must be carried out in an inert gas-protected or vacuum environment, which increases process complexity and cost.

 

• Cold working: Equipment is relatively simple, and traditional cold rolling mills and stamping machines can meet the requirements. However, titanium alloy has poor room-temperature plasticity and high yield strength, requiring large-tonnage equipment to overcome deformation resistance. The material has a high friction coefficient with the mold, making it prone to sticking and surface scratches. Special coatings for molds, matching special lubricants, and strict control of single-pass deformation to prevent cracking are necessary.

 

2. Deformation Capacity and Process Efficiency

• Hot working: Titanium alloy has good plasticity and large single-pass deformation (hot rolling reduction: 15%-30%), which can reduce the number of passes, improve efficiency, and is suitable for mass production of plates with a thickness of ≥5mm. It can also eliminate internal stress and avoid subsequent cracking.

 

• Cold working: Single-pass deformation is limited (cold rolling reduction: ≤5%-10%). Excessive deformation is prone to work hardening, requiring intermediate annealing to restore plasticity, which increases process steps and cycle time. However, it offers higher processing precision and is suitable for precision processing of thin plates with a thickness of ≤1mm.

 

 

1. Internal Structural State

• After hot working: Titanium alloy plates have a uniform, fine equiaxed grain structure with eliminated defects and high density. Adjusting processing temperature, speed, and cooling methods can optimize the structure-for example, controlled cooling to obtain martensite, or isothermal hot working to form an α+β duplex structure in materials such as Gr5.

 

• After cold working: Plates do not undergo recrystallization, presenting a deformed texture with grains elongated into a fibrous shape. They also have numerous crystal defects and concentrated internal stress, requiring subsequent annealing for improvement. However, the cold-worked texture can make the plate with superior strength and toughness in specific directions.

 

2. Core Mechanical Properties

• Hot-worked titanium alloy plates: Their core advantage is balanced comprehensive mechanical properties, with excellent coordination of strength, plasticity, toughness, and fatigue resistance. For example, hot-rolled Gr5 can withstand complex loads and is suitable for high-reliability scenarios such as aerospace structural components.

 

• Cold-worked plates: Through work hardening, their strength is significantly improved while plasticity slightly decreases. For example, cold-rolled Gr5 thin plates has high dimensional accuracy and low surface roughness. They are suitable for high-precision, high-surface-quality scenarios like medical devices and electronic casings. If it is required to balance the strength and plasticity, cold-worked plates can undergo low-temperature annealing to eliminate partial internal stress and moderately restore plasticity.

 

 

Category	Characteristics	Typical Applications
Hot Working	- Rougher Surface - Higher Ductility - Cost Effective	Aerospace Components Marine Parts
Cold Working	- Smooth Surface - Higher Strength - Superior Accuracy	Medical Implants Precision Instruments Electronic Devices Mobile Devices

 

 

Ruihang Group, a professional manufacturer of titanium and titanium alloy products, implements strict quality control throughout the entire production process from raw materials to finished products. We supply high-quality titanium plates, rings,forgings,bars, and other titanium products etc. For more details, please contact us via the Email: Sam.Rui@bjrh-titanium.com