ASTM B Standard Test Methods for Evaluating the Corrosion Resistance of Powder Metallurgy (P/M) Stainless Steel Parts/Specimens by Immersion in a. ASTM B Test Methods for Evaluating the Corrosion Resistance of Stainless Steel Powder Metallurgy (P/M) Parts/Specimens by Immersion in a Sodium. This standard is issued under the fixed designation B; the number immediately contact ASTM Customer Service at [email protected]
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ASTM B895 – 16
Log In Sign Up. A summary of the results obtained will be presented. The green and sintered densities of the materials are summarized in Table 4.
In Method 1, the test pieces are examined periodically and the time to the first appearance of rust is asfm to indicate the end point.
In Method 2, continued exposure to the sodium chloride solution is used to monitor the extent of corrosion as a function of time. The distance from the surface b8995 the TRS bars to the ast of the solution was at least 25 mm. The ratio of the volume of the air to the volume of the solution in the jar was about 1: An example of the experimental set-up is shown in Figure 1.
Any air bubbles were removed by gently swirling the solution. The jars were closed and the date and time of the test was recorded. After that the time interval was lengthened up to the first appearance of rust or a stain.
The corrosion life per Method 1 is the asfm of the last examination before the observation of a stain or rust. Method 2 follows the procedure of Method 1 then continues with periodic examination beyond the first appearance of a stain or rust.
In Method 2, specimens are ranked for degree of staining or corrosion according to the following: Based on this chart, a plot is made of the percentage of replicate specimens with a given rating versus the immersion time — Figure 4.
Plot of percentage of replicate specimens with a given astn versus immersion time.
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This practice provides a controlled corrosive environment that has been utilized to produce relative corrosion resistance information for specimens of metals exposed in a test chamber. Prediction of performance in natural environments has seldom been correlated with salt spray results when used as stand-alone data.
The apparatus for salt spray fog exposure consists of a fog chamber, a salt solution reservoir, a supply of suitably conditioned compressed air, one or more atomizing nozzles, specimen supports, provision for heating the chamber, and necessary means of control — see Figure 5.
Drops of the solution that accumulate on the ceiling or cover of the chamber shall not be permitted to fall on the specimens being exposed. Drops of solution that fall from the specimens shall not be returned to the solution reservoir for re-spraying.
The specimens, placed in the specimen supports for testing, are shown in Figure 6. TRS bars in their racks prior to salt spray testing.
The results for Method aatm testing of the SSN2 test bars are summarized in Table 10 and the data plotted in Figure Plot of percentage of replicate test specimens with a given rating versus immersion time. Photographs of the various test bars at different times of salt spray exposure. Photographs of the various test bars after h and h of salt spray exposure.
This is despite the fact that the carbon and nitrogen contents of this material were above the limit specified in MPIF Standard While the SSN2 material did not do as well in the immersion testing considerable scatter in the results it performed reasonably well in the salt-spray testing. As expected, the SS material was asmt to the series austenitic stainless steel grades.
The immersion test data exhibit considerably more scatter than the example provided in ASTM B; the graphical method suggested may only be suitable when the transition from Class A to Class B occurs at relatively extended times in our case, for SSN1 and SSN2 we had classes A, B, and C co-existing after a relatively short time.
This also perhaps indicates the need for at least ten specimens — giving a lower percentage impact if one test bar changes class.
Real life data are not always as well defined as the example given in the standard.
Method 2 of ASTM B is really only suitable for those materials that have an extended life prior to the appearance of corrosion products. Based on the results of this initial investigation it would appear that SSL should perform well in both the immersion and the salt-spray testing. Test bars from each group will be checked for iron or low-alloy steel powder contamination using the ferroxyl test prior to immersion or salt spray testing.
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