UGI® 4545 AIR Annealed – Premium Aerospace-Grade Precipitation Hardening Stainless Steel

UGI®15-5 PH AIR is suitable for

UGI®15-5 PH AIR offers good corrosion resistance, sometimes similar to that of type 18 Cr-8Ni austenitic steels in some cases.

Because of its low sulphur content and its very good micro-cleanliness, UGI®15-5 PH AIR has a poor chip breakability which can induce difficulties during machining, especially in drilling or finish turning operations. If possible, most of the machining operations to obtain the final parts have to be done in the A-condition (solution annealed) state in order to avoid too important tool wears during machining. Machining after a “precipitation hardening” heat treatment is not recommended because the higher the mechanical characteristics of the UGI®15-5 PH AIR bars to be machined, the higher the tool wears (and thus the lower the machining productivity). In A-condition, rough turning tests (ap = 1.5 mm; f = 0.25 mm/rev) performed on drawn bars have shown that the cutting speed to have a flank wear of 0.15 mm in 15 min of effective cutting with a STELLRAM SP4019 CCGT 09T308E-62 tool is ~ 145 m/min whereas that of a UGIMA®4542 (17-4 PH with improved machinability) is ~ 160 m/min. Depending on the machining operation, the machining productivity of UGI®15-5 PH AIR is found to be 10 to 30% lower than UGIMA® 4542.

Heat treatments carried out on UGI®15-5PH AIR are composed of two steps:

UGI®15-5 PH AIR is suitable for forging. Reheating must be carried out at a temperature between 1150 and 1200°C, forging between 1200°C and 950°C. Cooling after forging must be performed in air or oil. The parts obtained in this way have to be heat treated (solution annealing and eventual aging, see previous section)

Magnetic particle inspection and macro-graph

UGI®15-5 PH AIR complies with AMS 2300: Frequency/Severity rating 0/0

Macrostructure of UGI®15-5PH AIR is conforming to AMS 5659: class 1 to 4 are generally quoted severity A according to ASTM A604.

Available products:

Other products: contact the supplier

Pickling procedure: UGI®15-5 PH AIR is pickled in the same way as 630 grade steel.

UGI®15-5 PH AIR can be welded without preheating, using most welding techniques: GMAW or GTAW (with or without filler wire), LASER, resistance or electron beam welding, etc. If the mechanical characteristics of the weld area have to be at the same level as that of the base metal, no filler metal or homogeneous filler metal (such as AWS E/ER 630) have to be used and a post weld heat treatment of precipitation hardening (see the different PH heat treatment on page 4) has to be performed on the weld. If the mechanical characteristics of the weld area does not have to be at the same level as that of the base metal, a filler metal such as ER308LSi (19 9 L Si) can be used.

If no precipitation hardening heat treatment is done after welding, a stress relief heat treatment at 250/300°C could be useful to increase the toughness of the HAZ and avoid any risk of cold cracking due to their as-welded martensitic microstructures. Furthermore, it should be restated that the welding design should make allowance for the care required with all high steels with high proof stress: avoiding cut outs and sudden changes in cross section. For GMAW, we recommend the use of a protective gas made up of Ar+1%CO₂ or 1-2%O₂; for GMAW as well as for GTAW, gasses containing H₂ and N₂ must be avoided.