Is porosity common in 440C rod stock?
Is porosity common in 440C rod stock?
(OP)
I am (swiss screw) machining some .0469 pins out of 1/8" 440C bar stock, then hardening to 58RC. I have found porosity in the last 2 lots of Carpenter material. Is this a common problem with 440C?
I am considering switching to 440A drawn to size (.0469)to eliminate this defect. The yield strength is almost as high, and it is more available as wire than 440C...any thoughts?
I am considering switching to 440A drawn to size (.0469)to eliminate this defect. The yield strength is almost as high, and it is more available as wire than 440C...any thoughts?





RE: Is porosity common in 440C rod stock?
I would get in touch with the Carpenter Technical Service with your problem. It will help a lot if you have the Details of the product where you are seeing the porosity.
Addenda:
I have many many knife blades larger dicer blades and have never seen a problem. All my blades were machined ground with edge made on an grinder using a 20" wheel. I inspected the knife under 60 power microscope.
RE: Is porosity common in 440C rod stock?
RE: Is porosity common in 440C rod stock?
RE: Is porosity common in 440C rod stock?
This is the second lot where this has been observed, and the first lot was much more pronounced. We were careful to use a completely different batch of material, expecting not to see this again.
I must confess, that I did not believe that this was porosity at first. After several thousand dollars for micro x ray (sorting for good parts), mounting and sectioning (all done by a very prestigious firm), I have seen enough to be convinced.
I also seem to recall my EDM machinist complaining about 440C porosity and preferring to use other alloys. There is nothing like a hole in your finished mold.
RE: Is porosity common in 440C rod stock?
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: Is porosity common in 440C rod stock?
Are you are cooling?
Any time between hardening and tempering.
RE: Is porosity common in 440C rod stock?
RE: Is porosity common in 440C rod stock?
They can either broken or continuous.
RE: Is porosity common in 440C rod stock?
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: Is porosity common in 440C rod stock?
Is the Crucible technology equivalent to Carpenter's micro-melt technology? Just curious. I like being up on all the latest technologies.
Thanks,
Dave
RE: Is porosity common in 440C rod stock?
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: Is porosity common in 440C rod stock?
http://www.cartech.com/about.aspx?id=3394
http:/
As for how this relates to the OP is that Carpenter offers Micro-Melt® 440C Alloy (UNS S44004). Not sure if this would be of interest to sromkee1.
RE: Is porosity common in 440C rod stock?
I checked on the PM options, and at our present volume it is a non-starter, way too expensive. Too much further processing is required.
Wire (like 440A) is commonly available in standard grades, at ~$.03/ft. This would get me to final diameter and surface finish. It also would make a simple tensile test capable of discrimation for these typs of defects, whereas a tensile test on the 1/8" rod is not.
RE: Is porosity common in 440C rod stock?
VAR (AMS 5618) is harder to find than air melt (AMS 5630), but when you do is a lot less expensive than the P/M grades.