D. E. Wert, M. L. Schmidt, Carpenter Technology Corporation, Reading, PA
Custom 465 Stainless Alloy is becoming the alloy of choice for many aerospace applications due to its combination of high strength, good toughness, and good corrosion resistance. This presentation will cover recent results of stress corrosion cracking (K
ISCC) and hydrogen embrittlement (K
IHE) testing of Custom 465 Stainless Alloy in the standard solution/refrigerated/aged condition, and in the solution/refrigerated/cold worked/aged condition, after aging at 950°F or 1000°F. Additionally, fine structure analysis of the alloy will be presented in order to correlate some of the mechanical property/stress corrosion results with structural observations.
The KISCC and KIHE values to be discussed were generated using the RSLTM Rising Step Load Bend Testing System, manufactured by Fracture Diagnostics International, LLC. This machine and test method (ASTM F1624-05) allows KISCC values to be determined on fracture mechanics bend samples per ASTM E399/E1290 in far less time than the standard double cantilever beam test approach (incorporating procedures from NACE TM0177), which has been proven to be somewhat unreliable with high-strength corrosion-resistant grades. In addition, KIHE values are easily obtained with this apparatus, as it allows testing to be run at various controlled applied potentials. The data to be presented will represent samples held at potentials ranging from open circuit, where the test sample is freely corroding in 3.5% NaCl test solution, to -1.10 Vsce, simulating cathodic charging while being galvanically coupled to zinc.
The results of fine structure TEM analysis of Custom 465 Stainless alloy developed in collaboration with Penn State University’s Materials Research Institute will be presented. Thin foil specimens representing material in the solution/refrigerated/underage (H900), standard age (H950), and overage (H1000) conditions were characterized using TEM/EDS to gain an understanding of the fine structure and precipitation reactions that occur in this alloy. The TEM results will be correlated with mechanical property and stress corrosion test results.
This presentation covers the results of stress corrosion cracking and hydrogen embrittlement testing of Custom 465 Stainless Alloy. Testing was conducted on solution/refrigerate/age as well as solution/refrigerate/cold work/age material in the H950 and H1000 conditions. Test results were obtained by use of an RSL
TM Rising Step Load Bend Testing System, with test potentials ranging from open circuit to -1.1 v
sce. In addition, fine structure analysis of the alloy will be presented in order to correllate mechanical property and stress corrosion results with structural observations.
