UGI® 17-4PH AIR is a precipitation hardening martensitic stainless steel designed for aerospace and instrumentation with high strength and toughness. It has a martensitic microstructure and can be heat treated to different conditions with varying mechanical properties. Typical applications include parts requiring strength and corrosion resistance. The document provides detailed information on chemical composition, microstructure, heat treatments, mechanical properties, corrosion resistance, and quality control of UGI® 17-4PH AIR.

1. Composition variations meat AMS2248
19-05-2015 – REV 00
Technical Data Sheet
UGI®
17-4PH AIR - UGI®
4542 AIR
1
Chemical composition
(%)
C Si Mn Ni Cr Cu Mo Nb P S
≤ 0.07 ≤ 0.7 ≤ 1,0 3.5 – 5,0 15.0 – 17,0 3,0 – 5,0 ≤ 0.5
 5xC
≤ 0.45
≤ 0.025 ≤ 0.005
Ugitech SA
Avenue Paul Girod, CS90100, 73403 UGINE Cedex, www.ugitech.com
Although Ugitech takes special care to verify the exactitude of the information printed here, it
cannot guarantee that this information is exact, reliable, complete and reproducible as such by its
customers. Ugitech refuses all responsibility for the use of the data indicated above and invites
you to contact its Technical Assistance Department for a specific study of your needs.
General presentation:
UGI®
17-4PH AIR or UGI®
4542 AIR is a PH (Precipitation Hardening) martensitic stainless steel of premium quali-
ty, mainly designed for aerospace and instrumentation purposes. It is used for parts requiring a combination of
high strength and high toughness. Two versions are available: the standard EAF + AOD version, or the refined
version obtained by an advanced Electro-Slag Remelting technology.
Classification:
Martensitic stainless steel with Cu precipitation hardening
General standards:
UGI®
17-4PH AIR or UGI®
4542 AIR complies with the most demanding general specifications (AMS, EN, WL,
ASTM) and customer’s ones
EN WL AMS ASTM Other
EN 10088-3
AMS 5643
AMS 5622
ASTM A564
1.4542 1.4548 (ESR)
UNS S17400
UNS 17400 type II
UNS S17400
AISI 630
ASME SA564
Elaboration:
EAF + AOD - Standard version
EAF + AOD + ESR – Refined version, type II of the AMS 5622
Microstructure:
The microstructure is martensitic with some ferrite stringer. Depending on the metallurgical condition some re-
tained austenite and Cu precipitates can be part of the microstructure.
Microstructure of UGI®
17-4PH AIR in condition A, observed under light microscope

2. Composition variations meat AMS2248
19-05-2015 – REV 00
Technical Data Sheet
UGI®
17-4PH AIR - UGI®
4542 AIR
2
Chemical composition
(%)
C Si Mn Ni Cr Cu Mo Nb P S
≤ 0.07 ≤ 0.7 ≤ 1,0 3.5 – 5,0 15.0 – 17,0 3,0 – 5,0 ≤ 0.5
 5xC
≤ 0.45
≤ 0.025 ≤ 0.005
Ugitech SA
Avenue Paul Girod, CS90100, 73403 UGINE Cedex, www.ugitech.com
Although Ugitech takes special care to verify the exactitude of the information printed here, it
cannot guarantee that this information is exact, reliable, complete and reproducible as such by its
customers. Ugitech refuses all responsibility for the use of the data indicated above and invites
you to contact its Technical Assistance Department for a specific study of your needs.
Physical properties:
These properties are dependent on the metallurgical condition which is ordered. For information purposes, the ta-
ble below gives the values of some physical quantities of UGI®
17-4PH AIR in condition A (after solution anneal-
ing) and after age hardening H1150.
Condition A Condition H1150
Density 7750 kg/m3 7860 kg/m3
Weight of round bars (kg/m) 0.0062 x D² (D: diameter in mm) 0.0062 x D² (D: diameter in mm)
Weight of hexagonal bars (kg/m) 0.0068 x D² (D: diameter in mm) 0.0068 x D² (D: diameter in mm)
Elasticity modulus 197000 Mpa 197000 MPa
Thermal conductivity 17 W/m°C 17 W/m°C
Expansion ratio 10.8 x 10
-6
/°C 10.9 x 10
-6
/°C
Heat treatments and guaranteed levels of mechanical properties
According to ASTM A564/A564M and EN10088-3
After solution annealing treatment, performed between 1030°C and 1050°C, UGI®
17-4PH AIR or UGI®
4542 AIR
presents a soft martensitic structure with a hardness of around 35 HRC. If the metal is to be used in this condition
(called condition A), we recommend a stress-relieving heat treatment at 300°C. The latter will have no significant
effect on mechanical properties.
From the condition A, aging treatments can be carried out to obtain additional hardness (precipitation harden-
ing). The maximum hardness, of around 42 HRC (impact strength of 3 daJ/cm²) is obtained by aging at 480°C for
one hour (condition H900). Increasing the aging temperature gives a higher impact toughness but a lower tensile
strength or hardness. The choice of aging temperature is a matter of compromise between strength and tough-
ness, see table below.

3. Composition variations meat AMS2248
19-05-2015 – REV 00
Technical Data Sheet
UGI®
17-4PH AIR - UGI®
4542 AIR
3
Chemical composition
(%)
C Si Mn Ni Cr Cu Mo Nb P S
≤ 0.07 ≤ 0.7 ≤ 1,0 3.5 – 5,0 15.0 – 17,0 3,0 – 5,0 ≤ 0.5
 5xC
≤ 0.45
≤ 0.025 ≤ 0.005
Ugitech SA
Avenue Paul Girod, CS90100, 73403 UGINE Cedex, www.ugitech.com
Although Ugitech takes special care to verify the exactitude of the information printed here, it
cannot guarantee that this information is exact, reliable, complete and reproducible as such by its
customers. Ugitech refuses all responsibility for the use of the data indicated above and invites
you to contact its Technical Assistance Department for a specific study of your needs.
Metallurgical
condition
Coding
Heat
treatment applied
Guaranteed mechanical characteristics
Standards Conditions
Rm MPa
(KSI)
Rp 0.2
MPa
(KSI)
A % Z %
KV
(J)
HRC HB
Condition A
EN 10088-3 +AT
1030 / 1050°C annealing
 1200 - - - - -  360
ASTM A564
AMS 5622
AMS 5643
Cond A - - - - -  38  363
Hardened
ASTM A564
AMS 5622
AMS 5643
H900
1030 / 1050°C annealing
Air or oil cooling
+ hardening
1 h at 480°C / Air cooling
 1310
(≥ 190)
 1170
(≥ 170)
 10  40 -  40  388
H925
1030 / 1050°C annealing
Air or oil cooling
+ hardening
4 h at 495°C / Air cooling
 1170
(≥ 170)
 1070
(≥ 155)
 10  44  8  38  375
Over aged
EN 10088-3 +P1070 Annealing 1030 / 1050°C
Air or oil cooling
+ Tempering 4 h at 550°C,
Air cooling
1070/1270  1000  10 - - - -
ASTM A564
AMS 5622
AMS 5643
H1025
 1070
(≥ 155)
1 000
(≥ 145)
 12  45  50  35  331
ASTM A564
AMS 5622
AMS 5643
H1075
Annealing 1030 / 1050°C
Air or oil cooling
+ Tempering 4 h at 580°C,
Air cooling
1 000
(≥ 145)
 860
(≥ 125)
 13  45  50  32  311
EN 10088-3 +P960 Annealing 1030 / 1050°C
Air or oil cooling
+ Tempering 4 h at 590°C,
Air cooling
960 / 1160
(≥ 140)
 790
(≥ 115)
 12 - - - -
ASTM A564
AMS 5622
AMS 5643
H1100
 965
(≥ 140)
 795
(≥ 115)
 14  45  60  31  302
EN 10088-3 +P930 Annealing 1030 / 1050°C
Air or oil cooling
+ Tempering 4 h at 620°C,
Air cooling
930 / 1100  720  16 -  60 - -
ASTM A564
AMS 5622
AMS 5643
H1150
 930
(≥ 135)
 725
(≥ 105)
 16  50  80  28  277
EN 10088-3 +P800 Annealing 1030 / 1050°C
Air or oil cooling
+ Tempering 2 h at 760°C,
Air cooling
+ Tempering 4 h at 620°C,
Air cooling
800 / 950  520  18 -  80 - -
ASTM A564
NACE
MR0175
H1150M
 795
(≥ 115)
 520
(≥ 75)
 18  55  80  24  255

4. Composition variations meat AMS2248
19-05-2015 – REV 00
Technical Data Sheet
UGI®
17-4PH AIR - UGI®
4542 AIR
4
Chemical composition
(%)
C Si Mn Ni Cr Cu Mo Nb P S
≤ 0.07 ≤ 0.7 ≤ 1,0 3.5 – 5,0 15.0 – 17,0 3,0 – 5,0 ≤ 0.5
 5xC
≤ 0.45
≤ 0.025 ≤ 0.005
Ugitech SA
Avenue Paul Girod, CS90100, 73403 UGINE Cedex, www.ugitech.com
Although Ugitech takes special care to verify the exactitude of the information printed here, it
cannot guarantee that this information is exact, reliable, complete and reproducible as such by its
customers. Ugitech refuses all responsibility for the use of the data indicated above and invites
you to contact its Technical Assistance Department for a specific study of your needs.
Metallurgical
condition
Coding
Heat
treatment applied
Guaranteed mechanical characteristics
Standards Conditions
Rm MPa
(KSI)
Rp 0.2
MPa
(KSI)
A % Z %
KV
(J)
HRC HB
ASTM A564
NACE
MR0175
H1150D
Annealing 1030 / 1050°C
Air or oil cooling
+ Tempering 4 h at 620°C,
Air cooling
+Tempering 4h at 620°C
Air cooling
 860
(≥ 125)
 725
(≥ 105)
 16  50  80 24 / 33
255 /
311
Microcleanliness:
When UGI®
17-4PH AIR or UGI®
4542 AIR is produced via a double melting process with an ESR remelting , the
remaining inclusions are very small and are evenly distributed in the section. The following micro-cleanliness, ac-
cording to ASTM E45/A is guaranteed:
Type A B C D
rating
Thin Heavy Thin Heavy Thin Heavy Thin Heavy
 2 < 2  2 < 2  2 < 2  2 < 2
UGI® 17-4PH AIR is also available in an electro-slag-remelted (ESR) version that offers a higher level of micro-
cleanliness.
Magnetic particle inspection and macro-graph
UGI® 17-4 PH AIR complies with AMS 2300: Frequency/Severity rating 0/0
Macrostructure of UGI®17-4PH AIR is conforming to AMS 5622: classes 1 to 4 are generally quoted severity A
according to ASTM A604.
Corrosion resistance:
UGI®
17-4PH AIR or UGI®
4542 AIR offers good corrosion resistance, sometimes similar to that of type 18 Cr-8Ni
austenitic steels in some cases.
The structure of this grade makes it insensitive to intergranular corrosion and resistant to fatigue-corrosion as well
as to stress corrosion in some conditions (for example, see NACE standard for hydrogen sulfide environment).
Furthermore, good resistance to corrosion-erosion should be noted due to the association of high level mechani-
cal properties and corrosion resistance.
UGI®
17-4 PH AIR or UGI®
4542 AIR is pickled in the same way as 630 type grade steel. If necessary, the follow-
ing decontamination treatment process is recommended to move iron particles for example:
1/4 volume of 52% nitric acid (36° Baumé),
3/4 volume water
Ambient temperature
Duration must be defined
Wash carefully when the process is completed.

5. Composition variations meat AMS2248
19-05-2015 – REV 00
Technical Data Sheet
UGI®
17-4PH AIR - UGI®
4542 AIR
5
Chemical composition
(%)
C Si Mn Ni Cr Cu Mo Nb P S
≤ 0.07 ≤ 0.7 ≤ 1,0 3.5 – 5,0 15.0 – 17,0 3,0 – 5,0 ≤ 0.5
 5xC
≤ 0.45
≤ 0.025 ≤ 0.005
Ugitech SA
Avenue Paul Girod, CS90100, 73403 UGINE Cedex, www.ugitech.com
Although Ugitech takes special care to verify the exactitude of the information printed here, it
cannot guarantee that this information is exact, reliable, complete and reproducible as such by its
customers. Ugitech refuses all responsibility for the use of the data indicated above and invites
you to contact its Technical Assistance Department for a specific study of your needs.
Remark : the corrosion resistance of a stainless steel depends on many factors related to the composition of the
corrosive atmosphere (chloride concentration, presence or absence of oxidizing agents, temperature, pH, agita-
tion or no agitation, and so on), as well as to the preparation of the material (surfaces free from metal particles,
surface finish, such as hardening, polishing, and so on). Precautionary measures should be taken for certain tests
such as the sodium chloride fog test (standard ISO 9227): for example marking labels (that might cause corrosion
run-outs and reduce the test resistance time) should not be used on the sample.
The table below illustrates a performance scale in different environments:
Environment Behavior
Nitric acid Good
Phosphoric acid Restricted use
Sulphuric acid Restricted use
Acetic acid Average
Sodium carbonate Average
NaCl (Saline mist) Good
Humidity Excellent
Sea water Restricted use
Oil/gas Restricted use
Forging:
UGI®
17-4PH AIR or UGI®
4542 AIR is suitable for forging. Reheating takes place between 1150 and 1200°C,
forging between 1200°C and 950°C.
Cooling in air, water or oil. The parts obtained in this way can be used:
» Annealed (with an expansion treatment lasting 1 to 2 hours at 250°/300°C), or
» Hardened (with optional annealing + tempering for one hour at 480°C), or
» Softened (with optional annealing + tempering defined by the standards according to the desired level of
mechanical properties).
Welding:
UGI®
17-4 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 sec-
tion.

6. Composition variations meat AMS2248
19-05-2015 – REV 00
Technical Data Sheet
UGI®
17-4PH AIR - UGI®
4542 AIR
6
Chemical composition
(%)
C Si Mn Ni Cr Cu Mo Nb P S
≤ 0.07 ≤ 0.7 ≤ 1,0 3.5 – 5,0 15.0 – 17,0 3,0 – 5,0 ≤ 0.5
 5xC
≤ 0.45
≤ 0.025 ≤ 0.005
Ugitech SA
Avenue Paul Girod, CS90100, 73403 UGINE Cedex, www.ugitech.com
Although Ugitech takes special care to verify the exactitude of the information printed here, it
cannot guarantee that this information is exact, reliable, complete and reproducible as such by its
customers. Ugitech refuses all responsibility for the use of the data indicated above and invites
you to contact its Technical Assistance Department for a specific study of your needs.
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.
Products available:
Product Profile Surface Finishing Tolerance Size (mm)
Bar Round
Hot rolled & descaled K13 – K12 22 -115
Turned h11 - h10 22-115
Smooth Turned – Peeled Polished
h11 - h10
h9
22-115
22-55
Centerless Ground h9 - h8 - h7 5-115
Cold Drawn h9 5-21
Other profiles contact us
Applications:
UGI®
17-4 PH AIR or UGI®
4542 AIR is suitable for:
» Aerospace as premium Aircraft Quality
» Sensor manufacturing (weight, force, pressure…sensors)
» Medical Ancillary
» Mould steel