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Hydrogen embrittlement high-temperature and high-pressure hydrogen environment testing system

NegotiableUpdate on 01/19

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Overview

Hydrogen embrittlement high-temperature and high-pressure hydrogen environment testing system $r $n Hydrogen embrittlement refers to the phenomenon of brittle fracture of materials (especially metals) in a hydrogen environment due to the infiltration of hydrogen atoms. High temperature and high-pressure hydrogen environment testing is a key means of simulating the service conditions of materials in industrial scenarios such as petroleum refining and hydrogen energy storage, and evaluating their resistance to hydrogen embrittlement. This type of experiment is usually conducted in a hydrogen atmosphere with a temperature of 100-600 ℃ and a pressure of 1-20MPa, focusing on the diffusion and aggregation mechanisms of hydrogen atoms inside the material and their effects on mechanical properties.

Product Details

Hydrogen embrittlement high-temperature and high-pressure hydrogen environment testing systemPrinciples, Methods, and Applications

1、 Experimental background and core concepts

Hydrogen embrittlement refers to the phenomenon of brittle fracture of materials (especially metals) in a hydrogen environment due to the infiltration of hydrogen atoms. High temperature and high pressure hydrogen environment testing is a key means of simulating the service conditions of materials in industrial scenarios such as petroleum refining and hydrogen energy storage, and evaluating their resistance to hydrogen embrittlement. This type of experiment is usually conducted in a hydrogen atmosphere with a temperature of 100-600 ℃ and a pressure of 1-20MPa, focusing on the diffusion and aggregation mechanisms of hydrogen atoms inside the material and their effects on mechanical properties.

2、 Experimental purpose and application scenarios

Industrial demand

Petrochemical industry: Hydrogenation reactors and hydrogen pipelines (such as Cr Mo steel equipment in refining units) need to resist high temperature and high pressure hydrogen corrosion.

Hydrogen energy industry: hydrogen embrittlement risk assessment of hydrogen storage tanks and hydrogen fuel cell electrode materials (such as titanium alloys and aluminum alloys).

New energy equipment: material selection and life prediction for high-pressure hydrogen pipelines and hydrogen refueling station equipment.

scientific research value

Revealing the mechanism of hydrogen embrittlement (such as hydrogen induced dislocation accumulation and hydride precipitation);

Develop new materials that resist hydrogen embrittlement (such as surface coatings and alloy composition optimization);

Establish a hydrogen embrittlement prediction model (such as a life assessment formula based on diffusion kinetics).

3、 Experimental principle and key influencing factors

Influence dimension	mechanism of action	The impact on hydrogen embrittlement
temperature	Raising the temperature accelerates the diffusion of hydrogen atoms, but excessively high temperatures may cause hydrogen molecules to escape, forming The non-linear relationship between hydrogen partial pressure and temperature.	Medium temperature（The risk of hydrogen embrittlement is highest at temperatures between 200-400 ℃.
pressure	High pressure hydrogen gas increases the driving force for hydrogen atoms to penetrate the material, with each increase in pressure 1MPa， The hydrogen concentration can be increased by about 0.1mol/m3.	Pressure is positively correlated with hydrogen embrittlement sensitivity.
Material microstructure	Grain size, distribution of second phase particles, dislocation density, and other factors affect the capture and release of hydrogen.	Materials with fine crystal structure and low impurity content have stronger resistance to hydrogen embrittlement.
loading method	Static loads (such as tensile stress) and dynamic cyclic loads have different inducing effects on hydrogen embrittlement, and dynamic loads are more likely to accelerate crack propagation.	The hydrogen embrittlement threshold decreases by about under cyclic loading 30% -50%.

The impact of dimensional mechanisms on hydrogen embrittlement

The increase in temperature accelerates the diffusion of hydrogen atoms, but excessively high temperatures may cause hydrogen molecules to escape, forming a nonlinear relationship between hydrogen partial pressure and temperature. The risk of hydrogen embrittlement is highest at moderate temperatures (200-400 ℃).

High pressure hydrogen gas increases the driving force for hydrogen atoms to penetrate the material. For every 1 MPa increase in pressure, the hydrogen concentration can increase by about 0.1 mol/m ³. Pressure is positively correlated with hydrogen embrittlement sensitivity.

The microstructure, grain size, distribution of second phase particles, and dislocation density of materials affect the capture and release of hydrogen. Materials with fine crystal structure and low impurity content have stronger resistance to hydrogen embrittlement.

The induction effect of hydrogen embrittlement by static loads (such as tensile stress) and dynamic cyclic loads is different, and dynamic loads are more likely to accelerate crack propagation. The hydrogen embrittlement threshold decreases by about 30% -50% under cyclic loading.

4、 Experimental methods and standard system

Mainstream testing methods

High temperature and high pressure hydrogen environment tensile test: Apply tensile load to the sample under constant temperature and pressure, and measure the decrease in yield strength and elongation at break.

Hydrogen induced crack propagation rate test (CGR): Calculate the crack propagation rate (such as da/dN) through fatigue testing of prefabricated crack specimens in a hydrogen environment.

In situ hydrogen permeation test (Devanathan method): Using an electrochemical workstation to measure the permeation rate of hydrogen atoms through thin film materials and evaluate the hydrogen diffusion coefficient.

International and industry standards

ASTMG146: Method for assessing hydrogen embrittlement of metal materials in high temperature and high pressure hydrogen environments;

ISO16111: Technical Specification for Hydrogen Induced Cracking Resistant Steel for Petroleum and Natural Gas Industries;

NACETM0177: Test Method for Stress Corrosion Cracking Resistance of Materials in Hydrogen Sulfide Environments (Some clauses can be analogized to hydrogen environments).

5Hydrogen embrittlement high-temperature and high-pressure hydrogen environment testing systemExperimental equipment and process

core equipment

High temperature and high pressure hydrogen kettle: made of nickel based alloy (such as Inconel625), equipped with temperature control system (accuracy ± 1 ℃) and pressure sensor (accuracy 0.1MPa);

Mechanical testing system: servo hydraulic testing machine, capable of applying axial loads (range 0-500kN), supporting dynamic cyclic loading;

Hydrogen concentration monitoring devices, such as secondary ion mass spectrometry (SIMS) and pulse thermal analysis (PTA), are used to analyze the hydrogen distribution inside materials.

Degradation rate of mechanical properties:

Degradation rate=

Room temperature air performance value

Performance value under hydrogen environment - room temperature air performance value×100%

When the yield strength degradation rate is greater than 15% and the elongation degradation rate is greater than 20%, it is determined that the material has a high risk of hydrogen embrittlement.

Fracture time (t_f): Under constant stress, the shorter the fracture time of the sample, the stronger the sensitivity to hydrogen embrittlement. A "stress fracture time" curve can be established (such as the Larson Miller parameter model).

Hydrogen embrittlement index (HI): Calculated by the proportion of cleavage fracture surfaces in the fracture morphology (SEM observation), material design optimization is required when HI>30%.

Engineering cases and cutting-edge technologies

Case: 15CrMo steel for refining equipment

It was found in a hydrogen environment of 300 ℃ and 10MPa that the hydrogen embrittlement threshold stress of the steel decreased by 42% compared to room temperature air environment. Adding 0.5% V (vanadium) alloying can improve the hydrogen embrittlement resistance by 35%.

cutting-edge technology

In situ TEM hydrogen embrittlement observation: introducing a hydrogen atmosphere in transmission electron microscopy to observe the interaction between hydrogen atoms and dislocations in real time;

Digital twin model: combining finite element analysis (FEA) and hydrogen diffusion equation to predict hydrogen embrittlement weak areas in complex components;

Surface modification technology, such as magnetron sputtering deposition of Al ₂ O3 coating, can reduce the hydrogen permeability of titanium alloys by 2-3 orders of magnitude.

Safety precautions

Hydrogen leakage risk: Before the test, helium gas leak detection is required (leakage rate<1 × 10 ⁻⁹ Pa · m ³/s), equipped with explosion-proof walls and hydrogen concentration alarms (threshold<4% LEL);

High temperature and high pressure protection: The hydrogen kettle needs to undergo regular non-destructive testing (UT/RT), and operators need to wear fire-resistant clothing and heat-resistant gloves;

Hydrogen embrittlement sample treatment: The fractured sample may have residual hydrogen and needs to be annealed in a vacuum furnace (such as 300 ℃ × 24h) to avoid secondary embrittlement.