How to specify cast low-alloy steel?

[1jen]

Have a small investment cast part (carrier) which was originally made from 8620 bar stock. It is now an investment casting. How do I specify the material and/or heat treatment?

SAE 8620 is for wrought products however I have seen several foundries say they can pour 8620. ASTM A29 lists only chemistry. Do I need more than one spec?

Looking at past material certs, they did not call out a specification only the material number 8620. Hardness ranged from 70-90 RB from lot to lot, within each lot the hardness range was more refined (76-82, 84-90 ect...).

The carrier is used in a check valve with a service temp range from -60 to +400F. One side holds the softer seat material and the other side has a spring pushing against it. So I think this is the right material choice, just confused as how to specify a wrought material for a casting?

 

[swall]

You will need to specify the casting and then the heat treatment required to develop your required properties. For example, AMS 5333 for the casting, which is a spec for investment cast 8615 alloy. If the AMS is too stringent for your application, then purchase per the AMS, but delete things (with the P.O. wording) you don't need, like radiographic inspection. That covers the casting. The heat treat processing (hardness and/or carburizing)call out would be similar to what the drawing called out for the wrought 8620 version.

 

[arunmrao]

No harm in calling out for 8620 grade castings. The chemistry will be as per 8620 and the heat treatment cycle ,i.e the case depth and case hardness can be specified like you regularly do on bar products. If you need to mask some regions,you can show it in the drawing.

This way I have been producing 8620 grade castings to the satisfation of customers.

 

[GRoberts]

Have you looked at this as a potential specification for ordering?

ASTM A915 / A915M
Abstract

This specification covers carbon and low alloy steel castings having chemical analyses similar to that of the standard wrought grades. Several grades are covered, such as; SC 1020, SC 1025, SC 1030, SC 1040, SC 1045, SC 4130, SC 4140, SC 4330, SC 4340, SC 8620, SC 8625, and SC 8630. Castings shall be heat treated either by full annealing, normalizing, normalizing and tempering, or quenching and tempering. The steel shall conform to the requirements of chemical composition as specified.

 

[Flesh]

You may also consider ASTM A732 "Castings, Investment, Carbon and Low Alloy Steel for General Application, and Cobalt Alloy for High Strength at Elevated Temperatures." Grade 13Q (aka IC 8620).

 

[1jen]

Thank you very much! After reviewing the specs everyone listed, I am using ASTM A732, Grade 13Q. Thank you for the help.