ISO 16573-2:2022 pdf – Steel — Measurement method for the evaluation of hydrogen embrittlement resistance of high-strength steels — Part 2: Slow strain rate test.
1 Scope This document provides an evaluation method of the resistance of high-strength steels to hydrogen embrittlement (i.e. hydrogen delayed fracture) using slow strain rate test with hydrogen pre-charged specimens. The amount of hydrogen absorbed in the specimens is analysed quantitatively by thermal desorption analysis such as gas chromatography, mass spectrometry and so on. This document includes testing methods for either smooth or notched specimens. It is applicable to ferritic base steels. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature ISO 6892-2, Metallic materials — Tensile testing — Part 2: Method of test at elevated temperature ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1: Tension/compression testing machines — Calibration and verification of the force-measuring system 3? Terms? and? definitions No terms and definitions are listed in this document. ISO and IEC maintain terminology databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .iso .org/ obp — IEC Electropedia: available at https:// www .electropedia .org/ 4 Principle Figure 1 shows schematic sequences for the overall testing method including hydrogen pre-charging (such as electrochemical method described in ISO 16573-1), mechanical testing and hydrogen analysis. Mechanical properties such as, yield strength, tensile strength, fracture strength, elongation to fracture and reduction of area are measured by applying tensile load at slow strain rate before and after hydrogen charging. 6 Hydrogen charging methods 6.1 General There are four hydrogen charging methods: cathodic charging, hydrogen absorption in aqueous solution at free corrosion potential, hydrogen absorption in atmospheric corrosion environments and hydrogen absorption in high pressure hydrogen gas. The examples of the condition of each method are as follows. 6.2 Cathodic charging 6.2.1 Hydrogen charging solution To estimate the effect of hydrogen on the mechanical properties of steels, the hydrogen is forced to diffuse into the specimens by the cathodic charging method. For hydrogen pre-charging, the charging solution should be prepared in accordance with Table 1. Two kinds of solutions may be used for hydrogen pre-charging. Solution 1 may be used for introducing a relatively large amount of hydrogen to the specimens and Solution 2 may be used for introducing a small amount of hydrogen.
6.2.2 Hydrogen charging conditions The electro-chemical cell for hydrogen pre-charging may be placed in a 200 ml to 1 000 ml beaker. It is recommended that the anode of the electrochemical cell be made of platinum wire of spiral type of 0,5 mm in diameter and 2 m in length (counter electrode), and the specimen works as the cathode (working electrode). After the Pt wire and the specimen are placed in the cell, apply the constant current of its current density in the range of 0 A/m 2 to 20 A/m 2 by using potentiometer/galvanostat for 48 h. A charging time of 48 h is recommended, but other charging times may be used as long as a total time of 72 h is reached for hydrogen charging and the homogenization treatment by room temperature exposure after cadmium (Cd) plating. For materials with low hydrogen diffusion coefficient, the hydrogen charging time and the total time may be increased. The specimen’s surface area shall be calculated for proper current supply. The pre-charged hydrogen amount may be changed by varying the current density or pre-charging time. However, it is recommended to use fixed pre-charging time and current density to get reproducible test results.