Charpy (ISO V test piece) Values of low carbon, cold rolled, bar stock
Charpy (ISO V test piece) Values of low carbon, cold rolled, bar stock
(OP)
We are working on obtaining CE marking for the Pressure Equipment Directive of a valve. One of the requirements is the bending rupture energy measured on ISO V test piece is no less than 27J at the lowest scheduled operating temperature. The standard product uses 12L14, 1215 etc. which I am pretty sure will not meet this specification. I have called several mills and they have no idea what impact values are obtainable for 1018 or any other low carbon steel. Ideally looking for a material that meets this specification at -20 Celsius and has decent screw machine machinability (1018 not really ideal). If someone knows a place where rough Charpy numbers are available this would be great also. I have seen the general carbon content vs. transition curves.
Thanks for your help.
Thanks for your help.





RE: Charpy (ISO V test piece) Values of low carbon, cold rolled, bar stock
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I recommend that you contact Timken regarding one of their microalloy grades like MicroTec 2W65. They can also make controlled additions of S and Ca in order to improve machinability without producing elongated sulfide stringer-type inclusions that drastically reduce fracture toughness, especially at lower temperatures. Here are some links with basic information (no Charpy data):
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RE: Charpy (ISO V test piece) Values of low carbon, cold rolled, bar stock
You need to consider formability and possibly weldability issues if used in a valve.
RE: Charpy (ISO V test piece) Values of low carbon, cold rolled, bar stock
I reviewed the ASME B&PV Code earlier. From what I could understand, the table that exempts impact testing was all for plate stock grades. The valves are screw-in cartridge valves without any welds, all features are turned. I also had a 4140 quoted but added to much cost to work.
RE: Charpy (ISO V test piece) Values of low carbon, cold rolled, bar stock
No, this is not true. There are bar grades as well for service down to -20 deg C. Look at SA 675 bar grades.
RE: Charpy (ISO V test piece) Values of low carbon, cold rolled, bar stock
I don't have the code available in front of me (I will need to go back to the university library.)
I was looking at the impact test exemption curves and notes excerpted from UCS-66 of VIII-1. Do SA 675 bar grades fall under "Curve B applies to except for cast steels, all materials of Curve A if produced to fine grain practice and normalized which are not listed in Curves C and D below." or should I be looking somewhere else in the code? I am unfamilar with the ASTM material grade specifications and have not been able to find much on the internet so I will need to head to the library for that also.
Timken had some recommendations but did not have specific Charpy test data to know for sure.
If a heat treatment is not specified, will the impact values be all over the map from lot to lot of materials for a cold drawn or hot rolled bar stock?
RE: Charpy (ISO V test piece) Values of low carbon, cold rolled, bar stock
Yes, the following Grades of bar for SA 675 would fall under Curve A
Grade 45,50,55,60,65,70
RE: Charpy (ISO V test piece) Values of low carbon, cold rolled, bar stock
Yes, impact values will be all over the map from lot-to-lot if you do not specify composition limits, heat treatment parameters, grain size, etc.