Key Precautions for Machining, Heat Treatment and Daily Maintenance of D3 Steel Dies

To further standardize operating specifications for D3 steel during machining, heat treatment, production operation and daily maintenance, reduce common failures of D3 steel such as cracking, chipping and rusting, and extend the service life of dies made of D3 steel, we hereby organize and release the key precautions for the use and maintenance of D3 steel for reference and implementation by relevant enterprises and practitioners.

D3 steel features excellent wear resistance, high compressive strength and minimal quenching deformation, making it suitable for cold blanking, cold extrusion, forming dies and other working conditions. Nevertheless, D3 steel contains abundant carbides, moderate toughness, poor thermal conductivity, high susceptibility to welding cracks and no inherent anti-rust performance, so standardized operations must be followed in all processing stages of D3 steel.

Cutting processing of D3 steel shall only be carried out under the annealed state; only grinding is allowed after D3 steel is quenched. Strict temperature control is required during forging of D3 steel, followed by slow cooling after forging to prevent cracking caused by rapid temperature drop. Sharp right angles and corners should be eliminated in D3 steel die structures to lower stress concentration. Appropriate grinding wheels shall be adopted for grinding D3 steel with small feed rates and sufficient coolant to avoid surface burning and microcracks on D3 steel workpieces.

Heat treatment acts as a critical step that determines the comprehensive performance of D3 steel. Stepwise preheating is mandatory, and quenching temperature of D3 steel must be precisely controlled. Double tempering shall be conducted immediately after cooling of D3 steel; the tempering temperature can be adjusted according to practical application demands to stabilize dimensional accuracy, release internal stress and improve the operational stability of D3 steel dies. Cryogenic treatment is not recommended for complex and thin-walled D3 steel dies, as excessive residual stress will trigger cracking.

Dies manufactured from D3 steel cannot withstand heavy impact and overload, and sudden collision loads should be avoided. During continuous production with D3 steel dies, temperature rise must be controlled with adequate lubrication and cooling measures. Even force distribution is required during die assembly to eliminate excessive local pressure on D3 steel components. Sharp alternation between hot and cold environments is forbidden to prevent thermal cracks and premature failure of D3 steel dies.

Anti-rust treatment is the core of routine maintenance for D3 steel. All D3 steel die surfaces must be thoroughly cleaned and coated with anti-rust oil if production halts for a long time. For long-term storage of D3 steel dies, oil sealing and moisture-proof packaging are necessary. After each production shift, metal debris on D3 steel dies shall be cleared, and edges and cavities of D3 steel dies need to be inspected for chipping, cracks and surface scratches, with timely troubleshooting for any defects. Hard abrasive polishing is prohibited for coated D3 steel dies to preserve the integrity of surface coatings.