Project Description

AM355 (UNS S35500), also designated as Grade 634 in ASTM A564 and 08X15H5M3 in GOST 5632, is a chromium-nickel-molybdenum semi-austenitic precipitation hardening (PH) stainless steel developed for applications demanding high strength, excellent fatigue resistance, and reliable performance at moderately elevated temperatures. Unlike 17-7PH and 15-7PH, AM355 utilizes a nitrogen-enhanced composition (0.07–0.13% N) combined with a balanced chromium-nickel-molybdenum matrix to achieve superior mechanical properties after sub-zero cooling and tempering (SCT) heat treatment. SHUNFU METAL, certified to ISO 9001:2015 and API Q1, manufactures AM355 stainless steel bars under stringent process controls — from electric arc furnace (EAF) melting with AOD refining through precision forging and heat treatment — delivering consistent properties for critical rotating and structural components in the oil and gas industry.

AM355 Stainless Steel Bar — Overview

Originally developed for gas turbine compressor components in aerospace, AM355 has been widely adopted in the oil and gas sector for high-speed rotating shafts, compressor rotors, valve stems, wellhead fasteners, pump impellers, and downhole tool bodies where its exceptional fatigue strength and good corrosion resistance deliver long service life under cyclic loading conditions. The alloy achieves its characteristic high strength through a martensitic transformation induced by sub-zero cooling (approximately -73°C), followed by precipitation hardening during tempering at 450–540°C. SHUNFU METAL supplies AM355 bars in the solution-annealed condition (Condition A) and in heat-treated SCT conditions, with every production lot verified by in-house optical emission spectrometry (OES), tensile testing per ASTM E8, and Rockwell hardness testing per ASTM E18, supported by MTC documentation per EN 10204 Type 3.1.

AM355 Equivalent Grades — International Standards

Standard Designation
ASTM A564 / A705 Grade 634 / UNS S35500
AMS AMS 5747 (bar, forging), AMS 5548/5549 (sheet)
GOST 5632 08X15H5M3

No direct EN/DIN or JIS equivalents exist for AM355. SHUNFU METAL supplies bars certified to ASTM A564 Grade 634 and AMS 5747, with full heat traceability and API Q1 documentation provided as standard with every order.

AM355 precipitation hardening stainless steel round bar by SHUNFU METAL
AM355 (UNS S35500) Stainless Steel Bar
SHUNFU METAL

AM355 Applications — Oil & Gas Industry

The outstanding fatigue resistance and high strength-to-weight ratio of AM355 make it a preferred material for rotating equipment and cyclically loaded components in oil and gas operations. SHUNFU METAL supplies AM355 bars to manufacturers serving the following petroleum industry applications, with every production lot verified against ASTM A564 and AMS 5747 specifications:

Compressor RotorsCentrifugal and axial compressor rotor assemblies for gas lift, gathering, and pipeline booster stations.
High-Speed ShaftsTurbine and pump drive shafts operating at elevated rotational speeds under cyclic loading conditions.
Valve Stems & SpindlesGate and globe valve stems for high-cycle actuation in wellhead and pipeline service.
Wellhead FastenersHigh-tensile stud bolts, nuts, and tensioning components for API 6A flanged wellhead connections.
Pump ImpellersMultistage centrifugal pump impellers and wear rings for crude oil transfer and water injection service.
Downhole Tool BodiesLogging tool housings, perforating gun carriers, and subsurface instrumentation bodies.
Turbine BladesGas turbine compressor blades and stator vanes for pipeline compression and power generation packages.
Spring ComponentsHigh-cycle safety valve springs, check valve springs, and actuator return springs.
Shaft SleevesWear-resistant shaft sleeves and bearing journals for rotating equipment in refinery applications.

Supply Range — AM355 Bar Dimensions

SHUNFU METAL maintains dedicated production capability for AM355 bars across hot-rolled, cold-finished, and forged product forms, processed through ISO 9001:2015 controlled workflows with full process documentation. Ultrasonic testing per ASTM A388 / EN 10228-3 and liquid penetrant inspection per ASTM E165 are available for critical rotating component applications. The following dimensional ranges are offered as standard:

Product Form Diameter / Thickness Range Width Range Length (Standard) Condition
Hot Rolled Round 10 mm – 300 mm — 3000 – 6000 mm Solution Annealed (Condition A)
Cold Finished / Peeled Round 3 mm – 100 mm — 2000 – 6000 mm Condition A, SCT 850, SCT 950, SCT 1000
Hot Rolled Flat 10 mm – 150 mm 50 mm – 500 mm 2000 – 6000 mm Solution Annealed (Condition A)
Forged Round 100 mm – 800 mm — 1000 – 6000 mm Solution Annealed (Condition A)
Forged Flat / Block 50 mm – 400 mm 100 mm – 1000 mm 1000 – 5000 mm Solution Annealed (Condition A)

All bars are supplied with EN 10204 Type 3.1 Mill Test Certificates documenting heat number, full chemical analysis (including nitrogen content), mechanical test results, and dimensional compliance. For rotating equipment orders, SHUNFU METAL provides supplementary non-destructive testing (NDT) reports certifying internal soundness and surface integrity.

AM355 Chemical Composition per ASTM A564

The AM355 composition is distinguished by its controlled nitrogen addition (0.07–0.13%), which works synergistically with chromium, nickel, and molybdenum to stabilize the austenitic structure during solution annealing while promoting complete martensitic transformation upon sub-zero cooling. At SHUNFU METAL, every heat is verified by in-house optical emission spectrometry (OES) against ASTM A564 Grade 634 / AMS 5747 limits, with special attention to nitrogen content as it directly governs hardenability:

Element C Mn Si P S Cr Ni Mo N
Wt % 0.10–0.15 0.50–1.25 0.50 max 0.040 max 0.030 max 15.00–16.00 4.00–5.00 2.50–3.25 0.07–0.13

Composition conforms to ASTM A564 Grade 634 (UNS S35500) and AMS 5747. The nitrogen addition serves as a potent austenite stabilizer during solution treatment while lowering the martensite start temperature (Ms), ensuring complete transformation during sub-zero cooling. SHUNFU METAL’s API Q1 certified traceability links every finished bar to its original heat analysis, with nitrogen verification included on every MTC.

AM355 Mechanical Properties by Heat Treatment

AM355 achieves its mechanical properties through the SCT (Sub-zero Cooled and Tempered) process: solution annealing followed by deep cooling to approximately -73°C to transform the austenite to martensite, then tempering at the specified temperature to precipitate strengthening phases. SHUNFU METAL performs in-house tensile testing (ASTM E8) and Rockwell hardness testing (ASTM E18) on every production lot, with full results documented on the MTC. The following values represent minimum guaranteed properties per AMS 5747 for bar products:

Condition Tensile Strength
(MPa / ksi)		 Yield Strength
(0.2% offset, MPa / ksi)		 Elongation
(% in 4D)		 Reduction
of Area (%)		 Hardness
(HRC)
A (Solution Annealed)
1038°C ±14°C, rapid quench		 1034 max / 150 max 620 max / 90 max 25 min — 30 max
SCT 850
-73°C + 454°C temper		 1276 min / 185 min 1034 min / 150 min 10 min 30 min 40 min
SCT 950
-73°C + 510°C temper		 1448 min / 210 min 1276 min / 185 min 10 min 25 min 43 min
SCT 1000
-73°C + 538°C temper		 1310 min / 190 min 1103 min / 160 min 11 min 30 min 40 min

Values per AMS 5747 and ASTM A564 for bar products. Condition A provides maximum ductility for machining and forming operations. SCT 950 delivers the highest tensile and yield strength, while SCT 1000 offers a favorable combination of strength and ductility with improved toughness. SHUNFU METAL’s ISO 9001:2015 accredited laboratory validates all mechanical properties on representative specimens from each heat treatment batch, with API Q1 ensuring full material traceability throughout the supply chain.