Read an interesting datasheet on ACUBE 100 today

The datasheet on AMS 5918 (ACUBE 100) indicated that the ductility of the material is severely impacted from even a small amount of cold work :
Cold Working
High strength levels can be achieved in ACUBE 100 alloy through cold working processes. It should be noted that a significant loss of ductility results from even small amounts of cold work.
Taken from on 10/28/2014
After locating the material specification in a cold formed bushing requirement, I was interested in what the AMS 5918 was. I was even more surprised after reading the above excerpt. The AMS 5918 is the warm worked variation (in certain cases, warm working can have undesirable precipitates occur). Warm worked materials have 7 to 30% Elongation and 10 to 24% Reduction of Area.  These low Elongation and Reduction of Area numbers indicate a stiffness or brittleness that would indicate fatigue and shock resistance may be an issue.

Wear and galling resistance is toted as primary benefits of the grade, but it has a very low galling threshold. Galling threshold is listed as greater than 20KSI. While the >20KSI threshold (per ASTM G98) is impressive when compared to type 316 which is >1KSI and 440C only attains 18KSI, it is also telling when MP35N has a threshold of 5KSI. I must note that NITRONIC 60 in the annealed condition (AMS 5894) has a threshold of >50KSI (primarily dictated by its yield strength, rather than an overall hardness achieved).

We perform hot, warm and cold forging processes in Tipton on our various equipment, so its always good to stay abreast of materials that are being utilized by industry.

Forging super alloy and super stainless

Forging super alloy and super stainless is not an easy job. Working these alloys usually requires twice as much power as other alloy or stainless products. This is due to the alloys being very strong through their chemical composition - higher alloy grades inherently have greater value. That inherent value is before you even cut it, heat it and form it to the shapes and sizes required. Having the right size billet starting stock makes a difference in the overall forging time required and the resultant mechanical properties the item will have. The chances a forging house will be able to make a small part successfully is dependent upon the input billet, how many pieces regularly required and over how many years it will run.

When requesting a quotation for a forging, it is very helpful to provide the finished dimensions, and allow sales to provide the oversize amount needed to guarantee the part can be machined. It may be more stock to remove than you would like, but you should only have to machine it once. Some materials are tougher to forge and machine than others. If you have never machined the item before, this is a good time to talk to sales about machinability and tooling needs. Many times machine shops will win an order due to machine time underestimate. Some of these alloys will take twice as long to machine, due to the removal rates are not as good with the higher tensile and yield strengths.

Forgings can be provided in a multitude of ways and they have different amounts of value added service. Forging option for open die forgings are as follows: oversized with allowance to finish, rough ground, rough machined, and finish machined per print. We also can perform inspections at this stage (above and beyond the AMS/ASTM material requirements). Whether it is an ultrasonic to various criteria, charpy V notch, magnetic permeability, dye penetrant or radiograph - it is always best to use these types of inspections early when they can be performed early and with less complex geometry.

Most of our customers require actual mechanical testing for their forgings. The controlling specification would have an indication of whether testing is required, but the application or usage of that part is what should dictate the need. A non critical part could be verified that is has been supplied correctly through a simple hardness check. The options for actual mechanicals are testing from a forged coupon, using a prolongation of the piece or cut from item, and actually destroying a piece to determine properties.  Separately forged test coupons are normally the route taken, and provide a great insight to the properties of the actual forging. The actual forging should be hardness tested and compared to the coupon hardness to correlate the two properties. Using a prolongation or destroying the sample will provide results that can certify a batch as well, these would be used for more critical type requirements and help show how the material is responding in "as used" cross sections.