In this article we will consider the AMS 5844 / AMS 5845 grades in particular. AMS 5844/AMS 5845 bars are solution treated by heating within the range 1900-1925 deg F for 4-8 hours (with air cool to room temperature).
We explained in our first article how the combination of cold work reduction and ageing times and temperatures combine to vary the properties of UNS R30035 | MP35N™. To achieve the properties of AMS 5844/AMS 5845 grades, the blend of cold work and ageing time/temperature provides the highest strength and hardness combination available. After cold work, the material is aged at 1000-1200 degrees F for 4-4.5 hours, then air cooled. The combination of cold work and ageing provides the following minimum expected properties. We have provided a comparison of what the properties are for other aged grades plus 316 stainless:
|UTS (ksi)||YS (0.2%) ksi||Elong % (4D)||RA %||HRC|
|AMS 5845 up to 1.75” diameter||260||230||8||35||38 min|
|AMS 5845 up to >1.75” <2” diameter||235||225||8||35||38 min|
|AMS 5845 above 2” diameter||195||185||10||40||40|
|AMS 5845 up to 1.75” diameter||260||230||8||35||44 min|
|AMS 5845 up to >1.75” <2” diameter||235||225||8||35||–|
|AMS 5845 above 2” diameter||195||185||10||40||–|
|Alloy 718 – AMS 5662 / 5663||180||150||12||15||36|
|Alloy 718 – API 6ACRA||150||120-145||20||35||32-40|
The comparison shows the strength that can be achieved for a modest increase in density (8.41 g/cm3) compared to alloy 718’s 8.19 g/cm3. The gain in strength / weight ratio puts UNS R30035 at the forefront when specialist applications require strength and toughness but where weight is a key engineering concern.
Note: AMS 5845 – Solution heat treated, cold drawn and aged bars.
- Most of our customers find the material in the final aged condition expensive to machine, so prefer the unaged AMS 5844 material, which can be upgraded to AMS 5845 after they have produced the fastener or component they require. Our AMS 5844 material comes with an aged capability test result which shows what the material properties will be after ageing the component.
- Broder Metals Group also offer the option for the customer to provide us with the components they have machined from our material and we will age the components for them if they are not able to undertake the ageing process themselves. This can be based on the capability test results or we can undertake final full mechanical testing after ageing (at an ISO 17025 approved test house, under intent of 3.2 if required) to provide a fully certified product.
Corrosion resistance is still better than average, although not as good as in the material produced to meet the requirements of NACE MR0175 / ISO 15156, which is covered in article 3. Articles 4 and 5 will look at how to machine and weld UNS R30035.
Broder Metals Group hope that these articles are useful and would welcome enquiries for our stock range and any questions not covered.
Copyright © 2019 Broder Metals Group
Acknowledgement: all values quoted are courtesy of Carpenter Technology Corporation: “MP35N: A Superalloy for Critical OIL and Gas Applications”