The main causes of forging bursts include material defects, improper heating processes, and poor deformation control.
Material defects
Poor material properties (such as internal defects, impurities, and coarse grains) reduce material plasticity and increase the risk of cracking.
Improper heating processes
Insufficient heating: This results in insufficient material plasticity, making it prone to cracking during deformation.
Excessively low forging temperatures: This reduces the material’s deformability and can cause cracks.
Improper cooling: Rapid cooling or improper cooling methods can generate residual stress, leading to crack propagation.
Failure to control deformation: Excessive forging speeds or stress concentrations (such as areas of alloy element segregation) can easily cause cracks.
Preventative Measures for Forging Burst
Depending on the different causes of forging burst, the following targeted preventative measures can be taken:
Material Factors
Strict Material Inspection:
Perform standard inspections on raw materials and strictly control the content of harmful elements.
Defects should be promptly eliminated. Surface defects can be cleaned with tools such as a torch.
Present cracks in the raw material should be removed before forging, and warpage should be straightened.
Optimizing Material Processing:
Remove the material by peeling or grinding before heating and forging.
Use high-temperature homogenization to improve structural heterogeneity.
For excessive concentrations of certain harmful elements (such as boron), appropriately reduce the forging heating temperature.
Preventative Measures for the Heating Process
Temperature Control:
Control the charging furnace temperature. Temperature and heating rate
Avoid using fuels with excessively high sulfur content in flame furnaces
Avoid heating in highly oxidizing media to prevent oxygen diffusion into the forgings
Heat treatment optimization:
Improve microstructure through appropriate pre-heat treatment
Properly master the heating process to avoid excessively high quenching temperatures or prolonged holding times
Temperature reduction in the temper brittle zone should be avoided as much as possible
Forging process prevention
Temperature management:
Strictly control the forging temperature range to avoid excessively low temperatures
Ensure that the material’s deformation resistance matches the temperature
Preheat the tooling (generally 150-350°C)
Deformation control:
Start with light tapping, then increase the deformation after the microstructure is properly broken down
Total deformation per fire: Control the strain rate within the range of 30%-70%.
Use a spiral forging method, feeding from the large end to the small end.
For forgings with very low plasticity, processes such as plastic pads and canned upsetting can be used.
Speed Adjustment:
Select an appropriate strain rate based on the material properties.
For materials prone to cracking (such as magnesium alloys), use a press rather than a hammer forging.
The reduction per pass should not be too large (no more than 50mm per side).
Cooling Process Prevention
Cooling Method Options:
Spray Cooling: Cooling by blowing atomized water onto the forging.
Air Cooling: Cooling by blowing air.
Air Cooling: Cooling by evenly placing the forgings on a dry surface in still air.
Pile Cooling: Cooling in a basket in air.
Sand-ash Cooling: Cooling in a dry area. Cool in slag, ash, or sand (the temperature of the incoming ash and sand should be no less than 500°C).
Furnace cooling: Slowly cool in a furnace at 500-700°C.
Cooling precautions:
Avoid localized defects caused by excessive cooling.
Do not place forgings on damp surfaces or metal plates.
Avoid drafts.
Mold design precautions.
Structural optimization:
Avoid sharp corners and sections with significant thickness differences; adopt smooth transitions.
Add process holes as appropriate, converting blind holes to through holes.
Use closed and symmetrical structures whenever possible.
Use modular structures for complex molds.
Combining these preventative measures effectively reduces the risk of cracking during forging, improving product quality and production efficiency. Of course, if you have large-volume forging needs, consider partnering with Mulan Metal. With 12 years of forging experience, Mulan Metal has helped clients in over 30 countries complete their forging operations and has received widespread recognition. We look forward to hearing from you.
Here is our Custom forging Display：
