ASTM G2 - G 2M - 19

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Designation: G2/G2M −19

Standard Test Method for

Corrosion Testing of Products of Zirconium, Hafnium, and

Their Alloys in Water at 680°F (360°C) or in Steam at 750°F

(400°C)

This standard is issued under the ﬁxed designation G2/G2M; the number immediately following the designation indicates the year of

original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A

superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

1. Scope

1.1 This test method covers (1) the determination of mass

gain, and (2) the surface inspection of products of zirconium,

hafnium, and their alloys when corrosion tested in water at

680°F [360°C] or in steam at 750°F [400°C].

1.2 This test method is to be utilized in its entirety to the

extent speciﬁed herein as a product acceptance test.

1.3 This test method may be used on wrought products,

castings, powder metallurgy products, and weld metals.

1.4 Unless a single unit is used, for example corrosion mass

gain in mg/dm

, the values stated in either inch-pound or SI

units are to be regarded separately as standard. The values

stated in each system are not exact equivalents; therefore each

system must be used independently of the other. SI values

cannot be mixed with inch-pound values.

1.5 This standard does not purport to address all of the

safety concerns, if any, associated with its use. It is the

responsibility of the user of this standard to establish appro-

priate safety, health, and environmental practices and deter-

mine the applicability of regulatory limitations prior to use.

For speciﬁc precautionary statements, see Section 9.

1.6 This international standard was developed in accor-

dance with internationally recognized principles on standard-

ization established in the Decision on Principles for the

Development of International Standards, Guides and Recom-

mendations issued by the World Trade Organization Technical

Barriers to Trade (TBT) Committee.

2. Referenced Documents

2.1 ASTM Standards:

D888 Test Methods for Dissolved Oxygen in Water

E29 Practice for Using Signiﬁcant Digits in Test Data to

Determine Conformance with Speciﬁcations

3. Terminology

3.1 Deﬁnitions of Terms Speciﬁc to This Standard:

3.1.1 control coupons, n—zirconium alloy specimens of

known performance used to monitor the validity of the test.

3.1.2 etching, n—a process for removal of surface metal by

action of acids in water.

3.1.3 Grade A water, n—puriﬁed water having a pH of 5.0 to

8.0 and an electrical resistivity of not less than 1.0 MΩ·cm.

3.1.4 Grade B water, n—water prepared with deionized or

demineralized water having a minimum electrical resistivity of

0.5 MΩ·cm.

3.1.5 The stated values of pH and electrical resistivity are to

be met after the measured values are corrected to 77°F [25°C].

3.1.6 high mass gain coupons, n—zirconium alloy speci-

mens that have been specially heat-treated to produce a mass

gain higher than the maximum speciﬁed as acceptable value

used for verifying the severity of the test.

NOTE 1—For the purpose of standardization the term “mass gain” is

used, however within industry the terms “mass gain” and “weight gain”

are used interchangeably.

3.1.7 reagent grade, n—the grade of chemicals normally

used for analytical purposes.

4. Summary of Test Method

4.1 Specimens of zirconium, hafnium, or their alloys are

exposed to high-pressure water or steam at elevated tempera-

tures for 72 or 336 h. The corrosion is normally measured by

the gain in mass of the specimens and by the appearance of the

oxide ﬁlm on the specimen surfaces. In some instances, such as

weld evaluation, mass gain measurements are either impracti-

cal to make or not required. When so speciﬁed, appearance of

the specimen shall be the sole criterion for acceptance.

5. Signiﬁcance and Use

5.1 This test method is primarily used as an acceptance test

for products of zirconium, hafnium, and their alloys. This

This test method is under the jurisdiction of ASTM Committee B10 on Reactive

and Refractory Metals and Alloys and is the direct responsibility of Subcommittee

B10.02 on Zirconium and Hafnium.

Current edition approved Jan. 1, 2019. Published February 2019. Originally

approved in 1967. Last previous edition approved in 2011 as G2/G2M – 06 (2011)

ɛ1

DOI: 10.1520/G0002_G0002M-19.

For referenced ASTM standards, visit the ASTM website, www.astm.org, or

contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM

Standards volume information, refer to the standard’s Document Summary page on

the ASTM website.

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the

Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

standard has been widely used in the development of new

alloys, heat treating practices, and for evaluation of welding

techniques.

5.2 Specimens are normally tested after careful etching and

rinsing. Specimens with as-manufactured surfaces may also be

tested without further surface removal.

5.3 When tubing with a second material clad on the inner

surface is to be tested, the inner cladding shall be removed

prior to the test.

6. Interferences

6.1 Autoclave loads that have one or more specimens

showing gross oxidation may affect results on other specimens

in the autoclave by contamination of the environment.

7. Apparatus

7.1 The apparatus consists of equipment for (1) etching the

specimens when required, (2) measuring the specimen surface

area and mass, the water resistivity and pH, test temperature

and pressure, etch and rinse temperature, and (3) performing

the water or steam corrosion test at elevated temperature and

pressure.

7.1.1 Etching—An acid bath, a ﬂowing rinse, and a deion-

ized water rinse are needed for proper metal removal and

stain-free rinsing. Polyethylene or polypropylene tanks are

commonly used with a bottom feed for ﬂowing water rinses.

Specimen hangers are generally made of Type 300 series

stainless steel. When many specimens are processed, a me-

chanical dipper for the etching process is useful.

7.1.2 Autoclaves, constructed of Type 300 series stainless

steel or nickel base alloys such as UNS grade N06600 or

N06690 and are manufactured to conform to ASME (American

Society for Mechanical Engineers) and government regulations

governing unﬁred pressure vessels. The autoclave is ﬁtted with

devices for measurement and control of pressure and

temperature, safety devices, and venting valves. Control sys-

tems for pressure and temperature adequate to meet the

requirements of this standard are needed. Sample holders and

other internal accessories are also constructed of Type 300 or

400 series stainless steel, or nickel-base alloys such as UNS

grade N06600 or N06690.

NOTE 2—If autoclave heating is performed in an oven, the oven and not

the autoclave will have the automatic temperature-control equipment.

7.1.3 Measuring Equipment, capable of measuring speci-

men dimensions to 0.002 in. [5 × 10

–5

m] and a balance

capable of weighing specimens to1×10

–4

g are needed.

8. Reagents and Materials

8.1 Argon Gas, welding grade.

8.2 Grade A Water.

8.3 Grade B Water.

8.4 Detergents and Solvents, for specimen cleaning includ-

ing reagent grade ethanol and reagent grade acetone.

8.5 Hydroﬂuoric Acid (HF), reagent grade.

8.6 Nitric Acid (HNO

), reagent grade.

8.7 Sulfuric Acid (H

), reagent grade.

8.8 Nitrogen Gas, for purging or controlling oxygen con-

tent.

8.9 Argon-Hydrogen Mixed Gas, for purging or controlling

oxygen content.

9. Hazards

9.1 The chemicals used in preparing specimens for this test

are hazardous. Detailed information on safe handling of

organic compounds, acids and products of zirconium, hafnium,

and their alloys should be obtained from competent sources.

9.2 High-temperature, high-pressure autoclave operation

must be in accordance with government regulations and

manufacturer’s instructions.

9.3 Hydrogen gas used for addition to the autoclave steam

supply must be handled in accordance with guidelines for

explosives and ﬂammables.

9.4 Do not add cold water directly to the autoclave vessel in

order to accelerate cooling upon completion of testing.

10. Sampling, Test Specimens, and Test Units

10.1 The size and the quantity of the test specimens, the

method of selection, surface preparation, and test acceptance

criteria shall be speciﬁed in the product speciﬁcation or by

agreement between the purchaser and the seller as stated in the

purchase contract.

10.2 Each specimen and control coupons shall be individu-

ally identiﬁed.

11. Preparation of Apparatus

11.1 General requirements for new or reworked autoclaves

and parts of autoclaves previously used for testing materials

other than to this standard are as follows:

11.1.1 Before specimens are tested in a new or reworked

autoclave, or in one having new valves, tubing, gaskets, etc.,

which contact the test specimen, clean the apparatus

thoroughly, wipe with reagent grade ethanol or acetone, and

rinse twice with Grade B water. Dry the autoclave or auxiliary

equipment by vacuum cleaning or drain and wipe with a clean,

lint-free cloth, and inspect carefully to ensure freedom from

contamination. There shall be no visible contamination, such as

lubricant, residues, dust or dirt, loose oxides or rust, and oil or

grease ﬁlm on the water surface, internal surface, gasket, or

head surfaces.

11.1.2 Clean all new and reworked ﬁxtures and jigs to be

used in the autoclave, rinse in hot Grade B water. Autoclave the

ﬁxtures and jigs for at least 1 day at 750°F [400°C] in 1500 psi

[10.3 MPa] steam or at 680°F [360°C] in water. Inspect the

parts for corrosion product. If corrosion product is found or

electrical resistivity of the residual water after the test measures

less than 0.1 MΩ·cm, the parts should be cleaned and auto-

claved again.

11.2 General requirements for autoclaves and parts in con-

tinuous use for corrosion testing under this standard are as

follows:

G2/G2M − 19

11.2.1 With Grade B water rinse all autoclaves, ﬁxtures,

parts, and jigs that have been in continuous use and have

shown satisfactory behavior in prior tests. Inspect the ﬁxtures

and jigs for corrosion products after each test and rework and

re-prepare items showing loose corrosion product.

12. Calibration and Standardization

12.1 High Mass Gain Coupon Preparation—These coupons

shall be selected from a previously tested lot. The selected

material shall be heat treated to produce the desired mass gain.

Heating for8hat1652 65°F [(900 63°C] and cooling to 572

65°F [300 63°C] at a rate not exceeding 6°F/min [3.3°C/

min] will normally produce the desired mass gain.

12.2 Autoclaves:

12.2.1 Prior to use for product acceptance testing, an auto-

clave shall be proﬁled thermally as in 12.4.2 and shall

demonstrate acceptability by testing at least three control

coupons, one each at the top, middle, and bottom of useful

volume. The test results shall be incorporated in the certiﬁca-

tion document for the autoclave acceptance test. When desired,

high mass gain coupons may also be used.

12.2.2 Establishing Mass Gain Mean and Standard Devia-

tion of Control Coupons—The control coupon lot and, when

desired, the high mass gain coupon lot mass gain mean and

standard deviation shall be established by a minimum of one

autoclave test as follows:

12.2.2.1 Randomly select 12 specimens from the control

coupon lot or the high mass gain coupon lot respectively.

12.2.2.2 Prepare all specimens per the pretest requirements

of this test method.

12.2.2.3 Locate the 12 or 24 specimens in a ﬁxture or jig, in

accordance with Fig. 1, and place the ﬁxture or jig inside the

useful volume of the autoclave.

12.2.2.4 Complete the steam or water corrosion test in

accordance with any one of the four methods in 14.3.

12.2.2.5 Remove specimens and weigh in accordance with

the requirement of this test method.

12.2.2.6 Calculate and establish the mass gain mean and

standard deviation (n–1 method) of each set of coupons for the

test method used.

12.2.2.7 For product acceptance tests the mean value and

standard deviation for the control coupons may be the value

established in 12.2.2.6 or may be calculated periodically using

all accepted values determined over at least the preceding

3-month period but not less than 21 values.

12.2.3 An alternative method for establishing the mass gain

mean and standard deviation for the control coupons which are

used repeatedly is:

12.2.3.1 Expose the control coupons to be used in three

different tests, once each in the top, middle, and bottom of an

autoclave, and determine mass gain.

12.2.3.2 The mean value of each control coupon is the mean

for the three tests.

12.2.3.3 The standard deviation for the control coupon lot is

calculated by the (n–1) method using the data from all of the

control coupons taken from the same material lot.

12.2.4 The new or used autoclave is considered acceptable

if each control coupon mass gain is reproducible within the

previously established control coupon mean mass gain 63

standard deviations.

12.3 Use of Control Coupons:

12.3.1 Each autoclave run used for acceptance of product

shall contain at least three control coupons with one at the top,

one at the middle, and one at the bottom of the specimen load.

12.3.2 The control coupons may be as manufactured or

etched before testing, but if etched, the surfaces should exhibit

no stains, pits, or areas of abnormal etching attack.

12.3.3 An autoclave test is considered acceptable only if

each post-test control coupon mass gain is not less than the

established mean value minus 3 standard deviations and the

visual appearance of each control coupon is equal to or better

than the product acceptance standard. If a control coupon

post-test mass gain exceeds the mean value plus 3 standard

deviations, or the speciﬁed mass gain value, and one or more

test specimens from the corresponding location in the auto-

clave failed to meet the mass gain acceptance criterion, the

failed specimen(s) may be discarded and a new test made to

determine conformance.

12.3.4 Control coupons may be reused after removal of

oxide ﬁlm.

12.4 Calibration:

12.4.1 The temperature measurement and recording systems

used to determine conformance shall be calibrated at least

FIG. 1 Control Coupon and High Mass Gain Coupon Positioning

for Establishing Mass Gain Mean and Standard Deviation

G2/G2M − 19

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摘要：

ASTM G2 - G 2M - 19 是 ASTM 国际标准组织发布的关于钛及钛合金在高温高压环境中耐腐蚀性能测试的标准规范，该标准详细规定了试样制备、试验装置、操作步骤及结果评估方法，旨在评估钛材在特定腐蚀介质中的稳定性与耐久性。作为材料工程与工业腐蚀控制领域的关键参考文件，ASTM G2/G2M-19 为航空航天、化工设备、海洋工程等行业提供了统一的试验依据，帮助工程师和研究人员确保钛材料在严苛服役条件下的可靠性与安全性，同时避免因腐蚀失效导致的安全事故与经济损失。

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