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In modern industrial manufacturing, 304 stainless steel plates are widely used in food equipment, chemical containers, architectural decoration, medical devices, home appliance manufacturing and other fields due to their excellent corrosion resistance, good processability and high cost-performance ratio. However, in actual production, many customers have reported: why do the 304 stainless steel plates we purchased crack after processing such as bending, stamping, welding or deep drawing? This not only affects product quality, but also increases production costs and delivery cycles. So, is the cracking of 304 stainless steel plates after processing really a problem with the material itself? Or is it caused by improper processing technology or operation? This article will deeply analyze the real reasons for the cracking of 304 stainless steel plates after processing from multiple dimensions such as material characteristics, processing methods and environmental factors, and provide practical prevention and solutions. 1. Material Characteristics and Limitations of 304 Stainless Steel First, we must clarify: 304 stainless steel (i.e., 06Cr19Ni10) is an austenitic stainless steel, whose main components are 18% chromium and 8% nickel, with good toughness and ductility. Under standard conditions, the elongation of 304 stainless steel can reach more than 40%, which theoretically has excellent cold working performance. However, this material will undergo the phenomenon of “work hardening” during cold processing—that is, with the progress of plastic deformation, the internal lattice structure of the material is distorted, the dislocation density increases, leading to the increase of strength and hardness, while the ductility and toughness decrease significantly. When the processing deformation exceeds the bearing limit of the material, microcracks are likely to occur in the stress concentration area, and expand in subsequent processing or use, eventually leading to macroscopic cracking. Therefore, work hardening is one of the fundamental reasons for the cracking of 304 stainless steel plates after cold processing. This problem is particularly prominent in high-deformation processes such as deep drawing, large-angle bending or multiple stamping. 2. Improper Processing Technology is the Direct Inducement of Cracking In addition to the characteristics of the material itself, the rationality of the processing technology directly determines whether the 304 stainless steel plate will crack. The following are several common improper operations: 2.1 Excessively Small Bending Radius Although 304 stainless steel has good bending performance, it must follow the principle of “minimum bending radius”. Usually, its minimum bending radius should not be less than 1 time the material thickness (i.e., R≥1t). If forced to perform small-radius bending, the outer material will bear great tensile stress, and cracks are likely to occur at the bending angle. This problem is more obvious especially when the plate thickness is large. 2.2 Unreasonable Design of Stamping Dies During the stamping process, if the die gap is too small, the cutting edge is too sharp or the lubrication is insufficient, the material will be subjected to excessive shear force and friction during blanking or forming, resulting in local stress concentration and thus cracking. In addition, the unqualified surface roughness of the die will also aggravate material damage. 2.3 Non-standard Welding Process During the welding of 304 stainless steel, if the heat input is too large, the cooling speed is too fast or the shielding gas is impure, intergranular corrosion or hot cracks are likely to occur in the weld seam and heat-affected zone. Especially in multi-pass welding or thick plate welding, if the interpass temperature is not properly controlled, residual stress accumulates, which is very easy to cause post-weld cracking. 2.4 Lack of Intermediate Annealing Treatment For workpieces that require multiple cold processing, such as deep-drawn stainless steel sinks or containers, if intermediate annealing (such as solution treatment) is not arranged during the processing, the material will become brittle and hard due to continuous work hardening, and eventually crack in subsequent processing. 3. Impact of Material Quality and Surface Condition Although 304 stainless steel itself has good processing performance, the quality of materials on the market is uneven, and inferior materials are important external factors leading to cracking. 3.1 Substandard Composition or Impurity Doping Some low-cost 304 stainless steel plates may have insufficient chromium and nickel content, or be mixed with alternative elements such as manganese and nitrogen (such as low-quality materials like 201 and 202 pretending to be 304), resulting in reduced ductility and toughness of the material, which is more likely to crack during processing. 3.2 Surface Defects Defects such as scratches, indentations, cracks or oxide scales on the material surface will become stress concentration points during processing, inducing the initiation and propagation of cracks. 3.3 Improper Heat Treatment State 304 stainless steel should be used in the solution-treated state to ensure its optimal ductility and toughness. If the material is not fully solution-treated or the annealing is uneven when leaving the factory, there will be residual stress in the internal structure, which is prone to cracking during processing. 4. Potential Impact of Environmental and Service Factors In some special environments, even if the processing process is normal, 304 stainless steel plates may experience delayed cracking during subsequent use. For example: – Stress Corrosion Cracking (SCC) in Chloride Ion Environment: 304 stainless steel is relatively sensitive to chloride ions. In coastal areas or chlorine-containing media, if the material has residual stress, stress corrosion cracking may occur. – Embrittlement in Low-Temperature Environment: Although 304 stainless steel has good toughness at room temperature, its toughness will decrease in extremely low-temperature environments. If there is simultaneous stress concentration, brittle cracking may also occur. 5. How to Prevent Cracking of 304 Stainless Steel Plates After Processing? To avoid processing cracking, the following measures are recommended: – Reasonably Design Processing Technology: Ensure that the bending radius, stamping gap, welding parameters, etc. meet the requirements of material characteristics. – Select High-Quality Materials: Choose 304 stainless steel plates produced by regular manufacturers with standard composition and good surface quality, and verify the material through spectral analysis or chemical detection. – Optimize Processing Sequence: For complex parts, it is recommended to adopt the process of “processing—annealing—reprocessing” to eliminate work hardening in a timely manner. – Strengthen Lubrication and Mold Maintenance: Use special stainless steel processing lubricants to keep the mold clean and sharp. – Control Welding Quality: Adopt appropriate welding methods (such as TIG welding), control heat input, and perform post-weld heat treatment to eliminate stress. In summary, the cracking of 304 stainless steel plates after processing is not caused by a single reason, but the combined effect of material characteristics, processing technology, material quality and environmental factors. Enterprises should control material quality from the source, scientifically formulate processing plans, and strengthen process control to effectively avoid cracking problems and ensure product quality and production efficiency.