ASTM G150-99(2010) - 1.5.2010
 
Significance and Use

This test method provides a prediction of the resistance to stable propagating pitting corrosion of stainless steels and related alloys in a standard medium (see Note 1). The CPT test can be used for product acceptance, alloy development studies, and manufacturing control. In the case of product acceptance, the supplier and user must agree upon the preconditioning of the specimen with regard to surface finish. The test is not intended for design purposes since the test conditions accelerate corrosion in a manner that does not simulate any actual service environment.

Another method to determine the potential independent CPT with an electrochemical technique has been discussed in the literature (1-4). This test method involves a potentiodynamic (potential sweep) procedure performed on specimens at different temperatures. A comparison (2) of the test method described in this test method and the potentiodynamic technique has indicated no difference in the test result obtained.

 
1. Scope

1.1 This test method covers a procedure for the evaluation of the resistance of stainless steel and related alloys to pitting corrosion based on the concept of the determination of a potential independent critical pitting temperature (CPT).

1.2 This test methods applies to wrought and cast products including but not restricted to plate, sheet, tubing, bar, forgings, and welds, (see Note 1).

Note 1—Examples of CPT measurements on sheet, plate, tubing, and welded specimens for various stainless steels can be found in Ref (1). See the research reports (Section 14).

1.3 The standard parameters recommended in this test method are suitable for characterizing the CPT of austenitic stainless steels and other related alloys with a corrosion resistance ranging from that corresponding to solution annealed UNS S31600 (Type 316 stainless steel) to solution annealed UNS S31254 (6 % Mo stainless steel).

1.4 This test method may be extended to stainless steels and other alloys related to stainless steel that have a CPT outside the measurement range given by the standard parameters described in this test method. Appropriate test potential and solution must then be determined.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

 
2. Referenced Documents

D1193-06(2018)

Standard Specification for Reagent Water

G193-22

Standard Terminology and Acronyms Relating to Corrosion

G107-95(2020)e1

Standard Guide for Formats for Collection and Compilation of Corrosion Data for Metals for Computerized Database Input (Includes all amendments and changes 12/17/2020).

G46-21

Standard Guide for Examination and Evaluation of Pitting Corrosion

D1293-18

Standard Test Methods for pH of Water

G3-14(2019)

Standard Practice for Conventions Applicable to Electrochemical Measurements in Corrosion Testing

G1-03(2017)e1

Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens (Includes all amendments and changes 12/8/2017).

E691-23

Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

E177-20

Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods

G5-14(2021)

Standard Reference Test Method for Making Potentiodynamic Anodic Polarization Measurements