Key points of forging quality control (dual dimensions of technology and management)

　　The forging quality directly determines the strength, toughness, and fatigue life of the mold steel. The following is a full process control system covering materials, processes, and testing:

　　1、 Material source control

　　Steel billet selection

　　Purity: Requirement [S] ≤ 0.005%, [P] ≤ 0.015% (via vacuum degassing VD/VD process)

　　Density: The use of continuous casting billets must meet the ASTM E381 flaw detection standard to prevent shrinkage porosity

　　Case: Japan's Datong mold steel adopts ESR (electric slag remelting) process, and the inclusion grade is 2 levels lower than the national standard

　　Material certification

　　Please provide the original factory warranty certificate (MTC), which includes:

　　Chemical Composition (Spectral Analysis Report)

　　Low magnification tissue (sulfur printing, acid leaching test)

　　Ultrasonic Testing (UT) Report (Compliant with SEP1921 Grade D)

　　2、 Core parameters of forging process

　　Monitoring measures for consequences of exceeding the control range of key parameters

　　Initial forging temperature 1100-1150 ℃ (H13 steel) overheating → coarse grain size infrared thermometer (± 10 ℃)

　　Final forging temperature ≥ 850 ℃ (avoid low-temperature forging) Cold forging → Risk of cracking ↑ 300% thermocouple embedded in mold monitoring

　　Forging ratio ≥ 3:1 (important parts ≥ 5:1) Insufficient forging ratio → CAD simulation of deformation caused by discontinuous forging of fiber streamline

　　Cooling rate ≤ 30 ℃/h (high alloy steel) rapid cooling → martensitic transformation stress crack programmable slow cooling pit+temperature recorder

　　Process innovation:

　　Isothermal forging (mold temperature fluctuation of ± 5 ℃): used for aviation titanium alloy die forgings, with a 50% improvement in microstructure uniformity

　　Multi directional forging (alternate upsetting and elongation): eliminates anisotropy and increases impact toughness by 20%

　　3、 Forging defects and detection technology

　　Common types of defects

　　White spots (hydrogen embrittlement): UT testing should be conducted within 24 hours after forging, and the hydrogen content should be ≤ 2ppm

　　Inclusions: rated according to ASTM E45, Class A (sulfide) ≤ 1.5

　　Streamline disorder: Macroscopic corrosion test (1:1 hydrochloric acid aqueous solution), streamline needs to be consistent with the direction of force

　　Comparison of testing equipment

　　Traditional methods for testing projects, advanced technologies, and improved accuracy

　　Internal defect ultrasonic testing (UT) phased array ultrasonic testing (PAUT) defect detection rate of 90% → 99%

　　Surface crack magnetic particle testing (MT) and eddy current testing (ECT) can detect micro cracks of 0.1mm

　　Chemical Composition Spark Spectroscopy LIBS Laser Induced Breakdown Spectroscopy Analysis Time 5s/Element

　　4、 Collaborative optimization of heat treatment

　　Heat treatment after forging

　　Annealing: H13 steel requires spheroidization annealing at 780 ℃ for 4 hours, with a hardness of ≤ 229HB (increasing machinability by 30%)

　　Dehydration treatment: 250 ℃ × 24h slow cooling (for large forgings)

　　Performance verification

　　Hardness gradient: HRC testing from surface to core, fluctuation ≤ 3HRC

　　Impact test: Charpy V-notch impact energy ≥ 40J (-20 ℃ environment)

　　5、 Digital Quality Control

　　Forging process monitoring system

　　Real time collection: temperature, pressure, deformation data (1000 samples per second)

　　Abnormal warning: AI algorithm automatically determines the risk of folding and overheating (accuracy>95%)

　　Quality traceability system

　　Each steel billet is assigned a QR code, which records:

　　Smelting batch → Forging parameters → Heat treatment curve → Inspection report

　　Case: German SGL carbon forgings can be traced throughout the entire process, and customers can scan the code to check over 200 process parameters

　　6、 Industry benchmark comparison

　　Quality indicators for ordinary forging factories (such as Aubert&Duval in France)

　　Dimensional accuracy ± 1mm ± 0.3mm (CNC precision forging)

　　Defect rate 3% -5% ≤ 0.5% (PAUT full inspection)

　　Uniformity of organization, grain size of 6-8 grade, full cross-section, grade 8 or above (ASTM E112)

　　Key conclusions

　　Material is the foundation: Prioritize the selection of ESR/VAR process steel billets to control inclusions from the source

　　Process is the core: multi-directional forging+program-controlled cooling can improve tissue density

　　Testing is the guarantee: PAUT+LIBS technology combination achieves comprehensive defect screening

　　Data is the future: Establishing digital forging archives to achieve full lifecycle quality traceability

　　Execute mnemonic:

　　Three controls - temperature control, deformation control, and cooling control

　　Three inspections "- billet inspection, process inspection, and finished product inspection

　　'Three Nos' - Unqualified materials are not put into production, unqualified semi-finished products are not transferred to another process, and unqualified products are not shipped out of the factory

　　Through this system, mold forgings can meet aviation grade standards (such as AMS 2750) and their lifespan can be increased by more than three times!