17-4PH Plate ASTM A693 Stainless Steel Plate

17-4PH plate, UNS S17400 with AISI designation 630 and EN material number 1.4542, is the precipitation-hardening stainless steel that combines the workability of austenitic grades with strength levels normally reserved for tool steels. In the aged H900 condition the plate reaches a minimum tensile strength of about 1310 MPa, yet it starts life as a soft, weldable martensitic plate at roughly 38 HRC maximum, which is the entire point of the grade: fabricate in the soft condition, age to full strength after forming and welding, and avoid the distortion and machining cost of working a fully hardened material.

SS 17-4 PH Plate Specification

Grade	Stainless Steel 17-4 PH | UNS S17400
Standard	ASTM B625 / ASME SB625
Thickness	0.1mm To 100 mm
Length	2000mm, 2440mm, 3000mm, 5800mm, 6000mm, etc
Width	1000mm, 1219mm, 1500mm, 1800mm, 2000mm, 2500mm, 3000mm, 3500mm, etc
Surface	2B, 2D, BA, NO.1, NO.4, NO.8, 8K, mirror, checkered, embossed, hair line, sand blast, Brush, etching, etc
Finish	Hot rolled plate (HR), Cold rolled sheet (CR), 2B, 2D, BA NO(8), SATIN (Met with Plastic Coated)
Form	Sheets, Plates, Coils, Slatting Coils, Perforated Coils

Contact now

Chemical Composition (ASTM A693, UNS S17400)

The composition below is the A693 acceptance window. The defining pair is chromium plus nickel at the 4:1 ratio that gives the martensitic transformation, with copper and niobium added for the precipitation reaction that produces the hardening.

 

Element	Min %	Max %
Chromium (Cr)	15.0	17.5
Nickel (Ni)	3.0	5.0
Copper (Cu)	3.0	5.0
Niobium + Tantalum (Nb + Ta)	0.15	0.45
Carbon (C)	-	0.07
Manganese (Mn)	-	1.0
Silicon (Si)	-	1.0
Phosphorus (P)	-	0.040
Sulfur (S)	-	0.030

 

Read the chemistry against the heat-treating logic. The chromium range, 15 to 17.5 percent, gives the grade its corrosion resistance, comparable to 304 in mildly corrosive service. The nickel and the low carbon hold the martensite soft enough to machine before aging. The copper, at 3 to 5 percent, is the hardener: on aging at 480 to 620 deg C, copper precipitates out as fine particles inside the martensitic matrix and locks the dislocation structure, which is what lifts the yield strength from about 760 MPa in the annealed condition to over 1170 MPa at H900. The niobium addition controls grain growth and contributes a small secondary hardening effect.

 

Mechanical Properties: The Full Aging Envelope

17-4PH Plate ASTM A693 Stainless Steel Plate is ordered by condition, and the condition is set by the aging temperature. The values below are the typical minimums published by the specification and mill data for plate; the exact acceptance values depend on the condition ordered and the product form.

 

Condition	Aging Temperature	Tensile Strength (MPa)	Yield Strength (MPa)	Elongation	Hardness (HRC)
Condition A (annealed)	-	max 1250	approx. 760	-	max 38
H900	482 deg C	min 1310	min 1170	min 10%	min 40
H925	496 deg C	min 1240	min 1140	min 10%	min 38
H1025	552 deg C	min 1170	min 1070	min 12%	min 35
H1075	579 deg C	min 1140	min 1000	min 13%	min 32
H1100	593 deg C	min 1070	min 965	min 14%	min 31
H1150	621 deg C	min 1000	min 790	min 16%	min 28

 

The table is a selection tool in itself. H900 delivers maximum strength and hardness for wear surfaces and highly loaded brackets, at the cost of the lowest toughness. H1150 restores ductility and impact resistance for thicker sections and pressure-retaining duties, sacrificing about 25 percent of the H900 strength. Intermediate conditions H1025 and H1075 give the most used balance of strength, toughness and resistance to hydrogen embrittlement in sour service. The condition ordered must match the final application, because the plate cannot be re-aged in the field to a different condition without the full solution-treat and age cycle.

 

Physical Properties

 

Property	Value
Density	7.78 g/cm3
Melting Range	1400 - 1440 deg C
Modulus of Elasticity	196 GPa
Thermal Conductivity (100 deg C)	18.3 W/m.K
Mean Coefficient of Expansion (0-100 deg C)	10.8 x 10-6 /K
Magnetic	Magnetic in all conditions (martensitic)

 

Two physical notes matter in plate design. The grade is magnetic in every condition, unlike austenitic stainless, which affects proximity switches, solenoid valves and any magnetic-interference-sensitive assembly. The coefficient of thermal expansion is close to that of carbon steel, which simplifies dissimilar-metal joint design in structural applications.

 

Fabrication Sequence: Soft In, Hard Out

 

• Forming: plate is sheared, rolled or brake-formed in Condition A, where hardness is 38 HRC maximum and the material behaves like a workable martensitic stainless.
• Machining: drilling, milling and edge preparation are done before aging, avoiding the cost of machining at 40+ HRC.
• Welding: 17-4PH welds without preheat, with matching or 17-4 chemistry filler; the weld zone softens and is restored to full strength by the final aging treatment.
• Aging: the fabricated assembly is aged at the selected temperature, typically for 4 hours plus 1 hour per 25 mm of section thickness, and air-cooled.

 

One caution: the plate should not be aged below 480 deg C for long periods, and components that will be plated for corrosion protection require a hydrogen-embrittlement-relief step after plating, because the high-strength microstructure is susceptible. For sour-gas service, specify the H1025 or higher condition, where the improved toughness and reduced hardness are required by NACE MR0175 for this grade.

 

Corrosion Resistance

 

17-4PH Plate ASTM A693 Stainless Steel Plate offers corrosion resistance in the general class of 304 stainless in many media, with better resistance to atmospheric corrosion and to dilute acids than hardenable carbon or alloy steels. Its corrosion performance depends on the aging condition: higher-strength conditions (H900, H925) are more prone to stress-corrosion cracking in chlorides and should be avoided for chloride service, while H1150 and higher-aging conditions give markedly better SCC resistance. Where chloride cracking is a risk, the plate is used in the over-aged conditions or replaced by a duplex or nickel-base alloy.

 

Key Applications

 

• Aerospace structural plate, engine mount brackets and fasteners requiring high strength-to-weight.
• Pump shafts, valve stems, impellers and wear rings in the oil and gas, chemical and food industries.
• Marine and offshore hardware where 304 is too soft and 316L lacks the strength.
• Medical and surgical instruments, and moulds and dies requiring hardness with corrosion resistance.
• Paper and petrochemical equipment where strength and moderate corrosion resistance are both required.

 

Ordering and Inspection Notes

Order 17-4PH plate by UNS S17400 and the ASTM A693 standard, and always state the condition (for example Condition A or H900, or annealed-then-aged). The mill certificate must list the heat analysis with copper and niobium values, the mechanical results for the condition delivered, and the hardness. Confirm plate thickness tolerance to A20/A480, flatness, and the edge condition (sheared, plasma-cut or machined).

 

For pressure and sour service, request the applicable code data sheet and NACE MR0175 compliance note, plus EN 10204 3.1 certification for full traceability. Because the mechanical values change with condition, receiving inspection should verify hardness and, where specified, tensile test results against the ordered condition, not against the generic grade values.

 

17-4PH plate is the workhorse precipitation-hardening stainless: it bends, cuts and welds like a stainless in the soft state and delivers tool-steel strength after a simple age. Specified by condition, verified by certificate, it is the economical high-strength plate for the aerospace, oil and gas, and processing industries.

 

 

 

Hot Tags: 17-4ph plate, uns s17400 plate, astm a693 17-4ph, 17-4ph stainless steel plate, aisi 630 plate, precipitation hardening stainless steel plate, 17-4ph h900 plate, 17-4ph sheet