How to Avoid Common Defects Such as Cracks and Deformation in Dalian Forging Processing

How to Avoid Common Defects Such as Cracks and Deformation in Dalian Forging Processing

Cracks and deformation are the most frequent quality defects in Dalian forging production, commonly found in forgings for shipbuilding, mining and heavy machinery industries. These problems not only cause dimensional errors and surface damage, but may also lead to direct scrapping of finished parts, greatly increasing production costs and delivery risks. Most forging defects are not caused by raw material issues, but by non-standard control of heating, forming and cooling processes. Comprehensive refined process management can effectively eliminate cracks, deformation and other typical faults from the source.

Raw material pretreatment and heating control form the foundation of crack prevention. Excessive impurities and uneven grain structure in forging blanks are major triggers of forging cracks. Before processing, raw materials must be strictly inspected, with surface oxide scales, burrs and defective areas completely removed. Heating should adopt staged temperature rise to avoid excessive internal and external temperature differences that induce thermal stress cracks. For carbon steel and alloy steel forgings commonly processed in Dalian, heating temperatures must comply with standard ranges. Overheating and low-temperature forced forging are strictly prohibited to prevent toughness degradation and subsequent cracking.

Standardized forging forming procedures effectively reduce deformation defects. Unreasonable forging force, hammer frequency and deformation amount are the main causes of twisting, bending and local deformation. According to workpiece specifications, large heavy-duty forgings should adopt multi-stage light hammer pre-forming with gradually increased deformation to prevent uneven stress from single heavy striking. Uniform forging force corrects deformation trends, refines metal grains and improves material compactness, reducing residual stress accumulation during forming and avoiding subsequent deformation and hidden cracking risks.

Controlled cooling and post shaping are critical final procedures. Rapid quenching of high-temperature forgings is forbidden. Gradient slow cooling and sand burying cooling methods are adopted to release internal residual stress evenly and prevent warping, deformation and cold cracks. Special tooling positioning cooling is applied for easily deformed workpieces such as special-shaped, thin-walled and long-shaft parts. Subsequent flaw detection and precision correction eliminate invisible cracks and minor deformations. Full-process standardized management significantly improves the qualification rate of Dalian forgings and ensures stable structural strength and dimensional accuracy.