Standard No.:	QJ 2538A-2016
English Name:	Heat treatment of structure steel
Chinese Name:	结构钢的热处理
Professional Classification:	QJ    Professional Standard - Aerospace
Issued on:	2016-01-19
Implemented on:	2016-3-1
Status:	valid
Target Language:	English
File Format:	PDF
Word Count:	13500 words
Translation Price(USD):	560.0
Delivery:	via email in 1 business day

QJ 2538A-2016 Heat treatment of structure steel 1 Scope This standard specifies the general requirements, processes, quality assurance regulations, packaging and transportation, technical safety and environmental protection for heat treatment of structure steel. This standard is applicable to the heat treatment of structure steel used in aerospace products. 2 Normative references The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections) to, or revisions of, any of these publications do not apply to this standard. However parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document applies. GB/T 224 Determination of the depth of decarburization of steels GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature GB/T 229 Metallic materials - Charpy pendulum impact test method GB/T 230.1 Metallic materials - Rockwell hardness test - Part 1: Test method (scales A, B, C, D, E, F, G, H, K, N, T) GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method GB/T 1172 Conversion of hardness and strength for ferrous metal GB/T 4340.1 Metallic materials - Vickers hardness test - Part 1: Test method GB/T 6394 Determination of estimating the average grain size of metal GB/T 7232 Terminology of metal heat treatment GB/T 8121 The terminology of technological materials for heat treatment GB 15735 Requirements for the safety and health in production process of metal heat treatment GJB 2028 Magnetic particle testing GJB 2367 Liquid penetrant inspection QJ 500 Specification for carbon structural steel and structural alloy steel forgings QJ 903 Management regulations for process documents of space products QJ 1428A-2012 Temperature control and measurement of heat treatment furnace QJ 3131 Specification for the pot bath and quenching medium for heat treatment 3 Terms and definitions For the purposes of this standard, the terms and definitions given in GB/T 7232 and GB/T 8121 apply. 4 General requirements 4.1 Personnel 4.1.1 Managers in heat treatment production, technology and quality control shall possess certain professional knowledge, be familiar with their field of endeavor and have some practical experience. 4.1.2 Operators, instrumentalists and inspectors related to heat treatment shall undergo training and examination, only those who have obtained the qualification certificate can take up their posts. 4.2 Equipment and technological equipment 4.2.1 The types, main uses and requirements of commonly-used heat treatment equipment are shown in Table 1. Table 1 Types, main uses and requirements of commonly-used heat treatment equipment Equipment type Main uses Requirement Heating equipment Vacuum furnace Quench hardening, normalizing and annealing, tempering, stress relieving Annealing, normalizing and stress relieving shall be carried out using furnace types of Class IV or above as specified in QJ 1428A-2012, while quench hardening and tempering shall be carried out using furnace types of Class III or above as specified in QJ 1428A-2012 Air resistance furnace Protective atmosphere furnace Salt bath furnace Quench hardening, annealing, normalizing Fluidized particle furnace Quench hardening Drying oven Tempering and stress relieving Cooling equipment Nitrate bath Austempering cooling The temperature uniformity of the nitrate bath shall be controlled using furnace types of Class II or above as specified in QJ 1428A-2012. The capacity of the pot bath shall be sufficient to ensure adequate cooling capacity under continuous production conditions, generally more than ten times the weight of the workpieces Alkali bath Quenching Water/salt water tank Oil tank Auxiliary equipment Sandblaster Remove oxide scales - Washer Remove oil stain Press machine Correction Testing equipment Brinell hardness tester Test the hardness of raw materials and semi-finished products All hardness and standard test blocks shall be verified (or calibrated) in accordance with relevant regulations and remain within their validity period. Before use, the hardness tester shall be calibrated with a standard block, and the result shall conform to the indicated value of the standard block Rockwell hardness tester Test the hardness of finished products, semi-finished products or thin-walled parts Vickers hardness tester Test the microhardness of the material Leeb hardness tester Test the hardness of thick and large workpieces that are not convenient to be tested by other hardness testing methods 4.2.2 The control, measurement and verification of furnace temperature uniformity, thermocouples, compensating wires and thermal temperature instruments and meters for heat treatment equipment shall be carried out in accordance with QJ 1428A-2012. 4.2.3 The quenching bath shall be equipped with a circulating stirring and cooling device. It is not recommended to use compressed air for stirring. When necessary, the quenching bath can be equipped with a heating device. 4.2.4 The quenching bath shall be equipped with a temperature measuring instrument with a resolution not exceeding 5℃. 4.2.5 The protective atmosphere furnace shall be capable of adjusting and controlling the atmosphere inside the furnace according to the requirements of the heat treatment process, and the protective gas shall not directly erode the workpieces. 4.2.6 During the heat treatment, applicable lifting appliance, jigs, supports and other process equipment shall be provided. The design of tooling shall be reasonable, taking into account material selection, dimension, structure and usage environment, etc. When the deformation requirements of the workpiece are strict, special process equipment can be used. 4.3 Process materials 4.3.1 Generally, the quenching media are as follows: gases such as air, argon and nitrogen; water; 5% to 12% salt water; oil for L-AN15 and L-AN32 total loss systems; vacuum quenching oil, rapid quenching oil, bright quenching oil and rapid bright quenching oil, etc.

Contents Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 General requirements 4.1 Personnel 4.2 Equipment and technological equipment 4.3 Process materials 4.4 Process documents 4.5 Production environment 5 Process 5.1 Types and purposes of heat treatment 5.2 Process parameters 5.3 Normalizing, full annealing, isothermal annealing, partial annealing and recrystallization annealing 5.4 Quench hardening 5.5 Austempering 5.6 Tempering 5.7 Stress-relief annealing 5.8 Straightening 5.9 Prohibited and restricted processes 5.10 Common defects and preventive measures 6 Quality assurance provisions 6.1 Production process control 6.2 Inspection classification 6.3 Inspection items 6.4 Qualification inspection 6.5 Quality conformance inspection 6.6 Disposition of nonconforming products 6.7 Inspection methods 7 Packaging and transportation 8 Technical safety and environmental protection Annex A (Informative) Main process materials and requirements Annex B (Normative) Types and purposes of heat treatment of structure steel Annex C (Normative) Heat treatment parameters for quench hardening, normalizing, full annealing, isothermal annealing and recrystallization annealing Annex D (Normative) Comparison of hardness, strength and tempering temperature Annex E (Normative) Workpiece shape coefficient Annex F (Informative) Critical dimensions of through hardening for some structure steels Annex G (Informative) Common defects and preventive measures for heat treatment of structure steel workpieces Bibliography