GJB 9578-2018 (English Version)

Standard No.: GJB 9578-2018
Language: Chinese, Available in English version
Release Date: 2018
Published By: Military Standard of the People's Republic of China-General Armament Department
Latest: GJB 9578-2018

Scope: This appendix specifies the method for determining the hydrogen content in solid aluminum and aluminum alloys. This appendix is applicable to the determination of hydrogen content in solid aluminum and aluminum alloys, and the determination range is 0.05μg/g~2.0μg/g

Introduction

Interpretation of the core technology of the standard

Key indicators	Requirements for Class I parts	Requirements for Class II parts	Testing methods
Hydrogen content (2219)	≤0.14μg/g	≤0.14μg/g	Appendix A Thermal conductivity method
Oxide film (low magnification)	≤2 points/1000cm²	≤4 points/1000cm²	GB/T3246.2
Ultrasonic testing	Grade A/AA(GB/T6519)		Piece-by-piece testing
7A09-T73 electrical conductivity	≥22.0MS/m(38%IACS)		GB/T12966

In-depth analysis of material properties

Typical grade 2219-T852 must meet the following requirements when the thickness is ≤100mm:

Longitudinal tensile strength≥425MPa
Tangential elongation≥6%
Brinell hardness115HBW

Special state 7A09-T73 needs to pass 289MPa stress corrosion test (>20 days without cracks)

Key points of process control

Key parameters of cold compression deformation:

Deformation rate is strictly controlled in the range of 2%-4%
2A14 alloy needs to be deformed within 3 hours after quenching
Forging rings with outer diameter ≥3000mm need 8-16 points dimensional measurement

Comparison of new and old standards

New Grade	Old Grade	State Comparison	Main Changes
2A14	LD10	T652→CYS	Add T652 state performance requirements
7A09	LC9	T73→CGS1	Add conductivity classification determination

Implementation Suggestions

Purchasing Specifications: Forging category (I/II), ultrasonic testing level, and special performance requirements (such as 7A09 stress corrosion test) must be clearly marked

Acceptance focus:

Class I parts must achieve 100% performance testing and melt traceability
Focus on batch consistency of hydrogen content and oxide film
Large-sized forging rings (≥3000mm) require additional multi-point size testing

GJB 9578-2018 history

2018 GJB 9578-2018 Specification for aluminum alloy ring forgings for aerospace use