SS 17-4 PH

SS 17-4 PH | UNS S17400 | ASTM A564 | DIN 50602 | AMS 5642 | MIL-S-25043 | Grade 630 | WS 1.4542 | ASME SA564


T630 is a 17-4 PH martensitic precipitation hardening stainless steel with a unique combination of high strength and good corrosive resistance. Supplied in either the H1075 (H580) aged condition with a tensile strength of 1000 Mpa minimum (HB 311 min.), or the H1150 (H620) double aged condition with a tensile strength of 930 Mpa minimum (HB 277 min.). It is characterised by high tensile strength and high yield strength obtained by solution annealing, followed by a single or double low temperature (precipitation) age hardening treatment. Coupled with a corosion resistance comparable to 304 austenitic stainless steel in many corrosive environments.630 in the H1075 (H580) aged condition can be re-aged if necessary at a higher temperature simply by heating at the required temperature for the required duration.630 in the H1075 (H580) And H1150 (H620) aged condition, can also be re-aged at a lower temperature by re-solution annealing, followed by age hardening at the required temperature for the required duration.It is used extensively by the Marine, Aerospace, Chemical, Petrochemical, Food Processing, Paper and general metalwork industries. Here it is employed for applications such as: Pump Shafts, Aircraft Fittings, Valve Stems, Hydraulic Fittings, Studs, Bushings, Screws, Fasteners, Couplings, Wear rings, Rollers and Food Handling Equipment etc.. Material Magnetic in all conditions.

Stainless steels are known as high-alloy steels. They contain about 4-30% of chromium. They are further divided into martensitic, austenitic, and ferritic steels. Another group of stainless steels are known as precipitation-hardened steels. They are a combination of austenitic and martensitic steels.

Grade 17-4 stainless steel is the most widely used steel of the precipitation hardening grade steels. It has high toughness, strength, and corrosion resistance.


Colour Code Stocked Sizes
(Bar end) 
STOCKED SIZES 15.88 mm to 304.8 mm diameter.
Bar Finish
Peeled, Cold Drawn, Turned and Centreless Ground.

Related Specifications

Australia AS 2837-1986-630
Germany W.Nr 1.4542 X5CrNiCuNb17 4
W.Nr 1.4548 X5CrNiCuNb 17 4 4
Japan JIS G4303 SuS 630
USA AISI 630 AISI S17400
ASTM A564/A564M-99-630
SAE J467 17-4 PH
UNS S17400


Chemical Composition 

Min. % Max %
Carbon 0.07
Silicon 1.00
Manganese 1.00
Nickel 3.00 5.00
Chromium 15.00 17.50
Copper 3.00 5.00
Niobium 0.15 0.45
Phosphorous 0.04
Sulphur 0.03

Mechanical Test Requirements in Solution Annealed and Age Hardened Conditions – At Room Temperature

Condition A H900 (H480) H925 (H495) H1025 (H550) H1075 (H580) H1100 (H595) H1150 (H620) H1150M (H620M) H1150D (H620D)
Ruling Section Up to 200 mm Up to 200 mm Up to 200 mm
UTS Mpa (Min) 1310 1170 1070 1000 965 930 795 860
Yield Mpa (Min) 1170 1070 1000 860 795 725 502 725
Elongation % in 50mm (Min) 10 10 12 13 14 16 18 16
Hardness Rc 38 Max 40 38 35 32 31 28 24 24 33 Max
BHN 363 Max 388 375 331 311 302 277 255 255 331 Max
Impact Charpy – V ft/lbs (Min) 5 15 20 25 30 55 30
Joules (Min) 6.8 20 27 34 41 75 41

Mechanical Properties

Condition A H900 (H480) H925 (H495) H1025 (H550) H1075 (H580) H1100 (H595) H1150 (H620) H1150M (H620M) H1150 (H620D)
UTS Mpa 1100 1375 1310 1170 1140 1035 1000 860 950
Yield Mpa 900 1275 1205 1140 1035 930 860 600 800
Elongation % in 50mm 15 14 14 15 16 17 19 22 20
Hardness Rc 36 44 42 38 36 35 33 27 31
BHN 340 420 390 350 340 330 310 275 295
Impact Charpy – V ft/lbs 30 15 25 35 40 45 50 100 90
Joules 40 20 34 47 54 61 68 135 120

Refer Age Hardening temperature table

Low Temperature Properties

Retains relatively good ductility at sub zero temperatures, with impact properties greatly improved at higher ageing temperatures
Typical sub zero charpy V-notch impact properties

Test Temperature oF 10 -40 -112 -148 -320
oC -12 -40 -80 -100 -196
Impact Strength H925
16 9 5 5 3
22 12 7 7 4
ft – lb
58 40 15 12 4
79 54 20 16 6
ft – lb
93 76 48 37 6
126 103 65 50 8

Cold Working

Cold bending etc. will be limited by the high yield strength in all conditions.

Corrosion Resistance

Superior to the martensitic stainless range in all conditions, and equal to 302 or 304 austenitic stainless grades in most environments.For optimum corrosion resistance, surfaces must be free of scale and foreign particles. Finished parts should be passivated.


Heat uniformly to 2150/2200oF (1177/1204oC) – Hold for 1 hour at temperature prior to commencing forging.Do not forge below 1850oF (1010oC). Finished forgings should be cooled in air to below 90oF (32oC) prior to further processing in order to obtain optimum grain size and mechanical properties.Finally forgings will require to be solution annealed prior to age hardening as required.

Heat Treatment

Solution Annealed – Condition A

Heat to 1900 +/- 25oF (1040 +/- 15oC) – *Hold for 30 MinutesSections up to 75 mm – Oil Quench To Below 90oF (32oC) Sections over 75mm – Air Cool To Below 90oF (32oC)*Actual holding time should be long enough to ensure that the part is heated thoroughly through out its section

Dimensional Changes During Heat Treatment

Age hardening results in a slight dimensional contraction as follows:-Condition A to condition H900 (H480) – contraction 0.0004/0.0006 M/M Condition A to condition H1150 (H620) -contraction 0.0009/0.0012 M/M

Age Hardening

Material in the solution annealed condition may be age hardened as follows:-*Denotes Double Overaged

Condition H900 (H480) H925 (H495) H1025 (H550) H1075 (H580) H1100 (H595) H1150 (H620) H1150M (H620M)* Plus H1150D (H620D)* Plus
Heat to ±15oF 900oF 925 oF 1025oF 1075oF 1100oF 1150oF 1400oF 1150oF 1150oF 1150oF
±9oC 480oC 495oC 550oC 580oC 595oC 620oC 760oC 620oC 620oC 620oC
Hold for Hours 1 4 4 4 4 4 2 4 4 4
Cool to Below
90oF (32oC)
Air Air Air Air Air Air Air Air Air Air

Notes on Heat Treatment And It’s Effect On Structure – Corrosion Resistance Etc

The martensitic transformation temperature range for this grade is:-

Ms-        270oF    (132oC)

Mf-        90oF      (32oC)

Therefore to ensure complete transformation to martensite, it is most important that parts are always cooled to below 90oF (32oC) within 24 hours following Solution Annealing and before Age Hardening Treatment which should also be followed by an air cool to below 90oF (32oC).
The age hardening tempers the martensite resulting in an improvement in toughness. The higher the ageing temperature the more refined the martensite leading to greater ductility but slightly lower strength.N.B. Temperature control is critical during age hardening and any variations outside the given range could lead to less than satisfactory results.In the solution annealed condition resistance to stress corrosion cracking is low – improving at age hardening temperatures from 1025oF (550oC) upwards to a maximum at 1150oF (620oC) double aged.


Machinability in the solution annealed condition is similar to 302 and 304 austenitic stainless steel grades.Machinablity in the H900 (H480) condition is limited, improving as the age hardening temperature is increased to optimum machinability similar to 304 austenitic stainless steel grade in the H1150 (H620) condition.

Removing Heat Tint

The heat tint formed during age hardening, whilst having little effect on corrosion resistance, may be removed when required for appearance purposes by pickling or electro polishing.

Grinding and Polishing

440C in the hardened and tempered condition requires care with finish grinding and polishing to avoid overheating as this can lower the hardness and corrosion resistance.

Elevated Temperature Use

Excellent oxidation resistance up to 1100oF (540oC).Exposure to temperature range 600 – 900oF (290 – 480oC) long term may result in reduced toughness but this can sometimes be minimilized by using higher ageing temperatures. As a general guide for short term exposure at elevated temperatures the ageing temperature should be at least 50oF (28oC) above the working temperature.


May be welded satisfactorily by shielded fusion and resistance welded processes, however oxyacetylene welding is not recommended due to the posibility of carbon pick up Filler metal when required should be similar to the parent metal if strength is important otherwise standard austenitic stainless filler wire 308L may be satisfactory. Pre-heating is not generally required.Welding in the solution annealed condition may be carried out satisfactorily, however welding in the H1150 (H620) condition reduces the effects of high welding stresses. Following welding in the solution annealed condition, parts can be directly age hardened as required, however those in the H1150 (H620) condition should be re-solution annealed and then age hardened as required.


  • Nuclear reactor
  • Aircraft and gas turbines
  • Oil field
  • Chemical process components
  • Paper mill


UNS S17400
DIN 50602
AMS 5642
Grade 630
WS 1.4542

© FountainHead Alloys 1996