CQI-9 is a standard of the AIAG (American Automotive Industry Action Group). The full name is:
CQI-9: Special Process – Heat Treatment System Assessment (HTSA)
This is a process capability assessment guide for suppliers using heat treatment processes (such as quenching, tempering, carburizing, carbonitriding, annealing, etc.) in the automotive industry.
The main purpose of CQI-9
✅ To assist companies in identifying risks and defects in the heat treatment process
✅ To establish a standardized process control system
✅ To ensure that the metallographic structure, mechanical properties, and reliability of the product meet the standards
✅ To meet the quality requirements of OEM customers for "special processes" (such as GM, Ford, Stellantis)
The structure of CQI-9 (4th Edition 2020)
CQI-9 is divided into the following main parts:
1. Management Responsibility and Quality Planning (Management Responsibility)
Whether the organization has clearly defined responsibilities and authorities in the heat treatment process
Whether quality objectives, flowcharts, FMEA, and control plans are in place
Whether a continuous improvement mechanism and training materials for employees are in place
2. System Assessment (System Assessment)
Operation, maintenance, and documentation of the entire heat treatment system
Including process control, furnace temperature uniformity, Equipment calibration, etc.
3. Evaluation of sub-processes (process tables)
Contain specific requirements for different heat treatment processes. The most important sub-processes are:
Sub-process Process content CQI-9 requirements Brief description
Table A Carburizing: Control of carbon potential, temperature, depth of the carburized layer, subsequent quenching
Table B Hardening & Tempering: Ensuring hardness, microstructure consistency, process control of oil/water/gas quenching
Table C Gas nitriding: Control of ammonia flow, time, temperature, and depth of the nitrided layer
Table D Carbonitriding: Control of ammonia + carbon source, temperature, time, combined with carburizing and nitriding
Table E Annealing: Including spheroidization annealing, recrystallization annealing, etc., with requirements for the metallographic structure
Table F Normalizing: Control of temperature and cooling curve to avoid overheating/abnormal structure
Table G Vacuum heat treatment (vacuum HT): Control of cavity vacuum, temperature uniformity, coolant parameters
Table H Surface quenching (induction/flame): Control of induction coil, Frequency, hardening layer depth, thermal post-treatment
Table I. Atmosphere Control: Various atmosphere types such as nitrogen, ammonia, methanol decomposition gas, etc.
Table J: Control of gas boronization gas content, layer thickness, temperature, and time
4. Temperature Uniformity Test (TUS)
Conducted according to AMS 2750 or equivalent standards
Evaluation of the uniformity of the heat treatment furnace's temperature field and verification of heating quality
Conducted regularly, e.g., every 3 to 6 months
5. System Accuracy Test (SAT)
Verification of the accuracy of the thermocouple, temperature control system, etc.
Calibration frequency, method, and error limit are described in detail
✅ Example of specific operating requirements (using carburizing as an example)
Control Point Requirements
Furnace Temperature Control: The furnace temperature control system must have automatic recording and alarm functions.
Carburizing Atmosphere Control: The carbon potential control system (e.g., oxygen probe) must be calibrated and recorded regularly.
Surface Carbon Content Check: Regular sampling for metallographic analysis and determination of carbon layer depth.
Carburized Layer Hardness Check: Surface hardness must meet the drawing requirements (e.g., 58–62 HRC).
Process Map: Each furnace has a complete process log with furnace number, time, and setting parameters.
CQI-9 Self-Assessment System
Each project is rated as follows:
S (Satisfactory) Satisfactory
M (Minor) Minor problem
M (Major) Major problem
U (Unsatisfactory) Unsatisfactory or missing
The overall assessment results require a corrective plan to address major problems within 90 days.
General requirements: A full CQI-9 assessment (including TUS and SAT) is conducted every 12 months.
Which companies are required to implement CQI-9?
Manufacturers with heat treatment processes in the automotive industry include:
Tier 1 and 2 suppliers
Heat treatment outsourcing units
OEM-approved laboratories/production units
Summary
Project content
Standard name: CQI-9: Heat Treatment Systems Assessment
