1 Scope
This standard specifies a method, using ammonia gas acceleration test, for the detection of residual stress (including applied stress) in wrought copper and copper alloys. Such stress will result in material failure due to stress corrosion cracking during service or storage.
This standard is applicable to detection of residual stress in wrought brass as well as assembly parts and spare parts (with limited dimensions).
2 Definitions
2.1
stress corrosion cracking
spontaneous damage of metal caused by fracture under combined action of corrosion and residual or applied stress.
2.2
applied stress
stress in a body due to application of an external load.
2.3
residual stress
stress remaining within a body as the result of plastic deformation.
3 Principle
On basis of the principle of strong stress corrosion cracking susceptibility of brass in ammonia gas atmosphere, exposure of test pieces to an ammoniacal atmosphere for specified time, followed by examination of cracks at an appropriate magnification ratio.
4 Apparatus
4.1 pH meter.
4.2 Closed vessel: a bottle with ground stopper not less than 1000 mL in volume and a φ240 mm~φ280 mm desiccator.
Foreword i
1 Scope
2 Definitions
3 Principle
4 Apparatus
5 Reagents
6 Test Piece
7 Test Methods and Requirements
8 Test Procedures
9 Test Report
Annex A (Normative) pH Value of the Test Solution
