NickE
Materials
- Jan 14, 2003
- 1,570
Is passivation effective on high tensile strength, (>270ksi), quenched and tempered modified 420ss?
Our customer is using the material as as flexure strap on a power washer, the assembly is the SS strap clamped btw a galvanized plate, and a 380 Al casting. eventually the crevices begin to show some corrosion ruining the highly prepared surface and causing fatigue failure initiation and subsequent failure.
Chemistry of MOD420SS:
C: 0.36-0.40%
Si: 0.30-0.50%
Mn: 0.45-0.65%
P: MAX 0.025%
S: MAX 0.010%
Cr: 13.2-13.8%
Mo: 0.90-1.10%
This is a special SS melted in small heats and with extremely low inclusion counts. We stamp the parts from ~HRc 50 coil and then do some edge/surface finishing in order to increse the fatigue life. Our custome asked if passivation would help prevent the corrosion from starting.
Will it?
MY thoughts: redesign or change materials since this steel is barely stainless.
nick
Our customer is using the material as as flexure strap on a power washer, the assembly is the SS strap clamped btw a galvanized plate, and a 380 Al casting. eventually the crevices begin to show some corrosion ruining the highly prepared surface and causing fatigue failure initiation and subsequent failure.
Chemistry of MOD420SS:
C: 0.36-0.40%
Si: 0.30-0.50%
Mn: 0.45-0.65%
P: MAX 0.025%
S: MAX 0.010%
Cr: 13.2-13.8%
Mo: 0.90-1.10%
This is a special SS melted in small heats and with extremely low inclusion counts. We stamp the parts from ~HRc 50 coil and then do some edge/surface finishing in order to increse the fatigue life. Our custome asked if passivation would help prevent the corrosion from starting.
Will it?
MY thoughts: redesign or change materials since this steel is barely stainless.
nick
