Stainless Steel AM-355-CRT
Supply condition
UNS S35500 · also Alloy 355, Alloy 634
CRT = cold rolled (Condition A strip) and tempered/aged
Highest-strength strip/spring condition; use for thin flat springs, diaphragms and clamps where forming is done before final ageing.
Values for the CRT condition
Other AM-355 tempers and conditions
AM-355 is listed in 5 conditions; see the grade overview at AM-355.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Supply condition for forming, machining and welding before the customer runs the SCT hardening cycle. | 450 | 1,000 | 25 | 25 HRC | — |
equalized, sub-zero cooled and tempered at 540 °C | Slightly lower strength than SCT 850 but better ductility, toughness and stress-corrosion behaviour; preferred for thick sections and higher service temperature. | 1,000 | 1,170 | 19 | 37 HRC | 2.2 % IACS |
Double aged | Simplified hardening route for sheet and welded assemblies where sub-zero cooling is impractical; strength somewhat below SCT 850. | 1,030 | 1,240 | 12 | 39 HRC | 2.2 % IACS |
SCT850Default equalized, sub-zero cooled and tempered at 455 °C | Peak-strength aerospace condition — choose when maximum tensile/fatigue strength is the driver and toughness demands are moderate. | 1,070 | 1,275 | 17 | 40 HRC | 2.2 % IACS |
CRTThis page Cold rolled (Condition A strip) and tempered/aged | Highest-strength strip/spring condition; use for thin flat springs, diaphragms and clamps where forming is done before final ageing. | 1,590 | 1,720 | 5 | 48 HRC | — |
What is AM-355-CRT?
AM-355-CRT is AM-355 supplied in the CRT condition — highest-strength strip/spring condition; use for thin flat springs, diaphragms and clamps where forming is done before final ageing. AM-355-CRT has a yield strength of 1,590 MPa (231 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 200 GPa (29 Msi). AM-355-CRT has a density of 7.91 g/cm³ (0.286 lb/in³), heavier than 76% of stainless steel grades. It melts at 1,400°C (2,552 °F). SCT850 is the default condition FabDigit quotes; CRT is available on request or by drawing note.
Advantages
- High strength — 1,590 MPa (231 ksi), better than 100% of stainless steel grades
Limitations
- Limited ductility — 5%, worse than 100% of stainless steel grades
- Difficult to machine — 15/100, worse than 100% of stainless steel grades
- Limited formability — 5/100, worse than 99% of stainless steel grades
- Difficult to weld — 15/100, worse than 98% of stainless steel grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 91% of stainless steel grades
AM-355-CRT properties
Typical room-temperature values for AM-355-CRT; 12 are specific to this condition. Other listed values are AM-355 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
AM-355-CRT has a density of 7.91 g/cm³ (0.286 lb/in³), heavier than 76% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
AM-355-CRT has a yield strength of 1,590 MPa (231 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
AM-355-CRT is rated for continuous service to 400°C (752 °F). It conducts heat at 16.3 W/m·K (9.42 BTU/hr·ft·°F), better than 68% of stainless steel grades. Thermal expansion is 11.6 µm/m·K (6.44 µin/in·°F).
Electrical3
AM-355-CRT conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (52/100), worse than 76% of stainless steel grades.
Sustainability4
Producing a kilogram of AM-355-CRT takes about 57 MJ of energy and emits 4.6 kg of CO₂ — more than 62% of stainless steel grades. Typical recycled content is 40%.
Manufacturability8
AM-355-CRT's machinability is poor (15/100, worse than 100% of stainless steel grades); weldability poor (15/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AM-355-CRT
Is AM-355 easy to machine?
Machine in Condition A wherever possible; in SCT 850 use rigid setups, positive-rake carbide or ceramic, heavy feeds and low speeds to cut under the work-hardened layer, with flood coolant.
Can AM-355 be welded?
GTAW/GMAW/EB weld in Condition A with matching or AM-355 filler, low heat input and no preheat, then run the full equalize–refrigerate–temper cycle to restore joint strength; welding after hardening is not recommended.
Can AM-355 be formed, bent or molded?
Cold form only in Condition A (austenitic, work-hardens rapidly — allow generous bend radii and interstage annealing); hot forge 1150–950 °C followed by re-annealing.
What surface finishes work on AM-355?
Passivate per AMS 2700/ASTM A967 after machining; electropolishing and fine mechanical polishing work well, and shot peening is common to raise fatigue life in hardened parts.
AM-355 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Chigher than AM-350 (0.07–0.11) — the main strength difference | 0.1 – 0.15 | 0.13 |
| Mn | 0.5 – 1.25 | 0.9 |
| Si | ≤ 0.5 | 0.3 |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Cr | 15 – 16 | 15.5 |
| Ni | 4 – 5 | 4.5 |
| Mo | 2.5 – 3.25 | 2.9 |
| Naustenite stabiliser controlling the transformation response | 0.07 – 0.13 | 0.1 |
| Fe | balance | — |
AM-355-CRT — frequently asked
What is AM-355-CRT used for?
AM-355-CRT is typically used for aircraft forgings, structural fittings and fasteners. In short: stronger than AM-350; forging-grade PH stainless; 40 HRC after SCT.
What is the yield strength of AM-355-CRT?
AM-355-CRT has a typical yield strength of 1,590 MPa (231 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is AM-355-CRT easy to machine?
Not especially — machinability is rated poor (15/100, worse than 100% of stainless steel grades). Machine in Condition A wherever possible; in SCT 850 use rigid setups, positive-rake carbide or ceramic, heavy feeds and low speeds to cut under the work-hardened layer, with flood coolant.
Can AM-355-CRT be welded?
Not readily — weldability is rated poor (15/100). GTAW/GMAW/EB weld in Condition A with matching or AM-355 filler, low heat input and no preheat, then run the full equalize–refrigerate–temper cycle to restore joint strength; welding after hardening is not recommended.
What surface finishes work on AM-355-CRT?
Passivate per AMS 2700/ASTM A967 after machining; electropolishing and fine mechanical polishing work well, and shot peening is common to raise fatigue life in hardened parts.
Can AM-355-CRT be formed, bent or molded?
Cold form only in Condition A (austenitic, work-hardens rapidly — allow generous bend radii and interstage annealing); hot forge 1150–950 °C followed by re-annealing.
What is the maximum service temperature of AM-355-CRT?
AM-355-CRT is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AM-355 SCT850 and AM-355-A?
SCT850 is the default condition — peak-strength aerospace condition — choose when maximum tensile/fatigue strength is the driver and toughness demands are moderate. A: supply condition for forming, machining and welding before the customer runs the SCT hardening cycle. Yield strength is 1,070 MPa in SCT850 versus 450 MPa in A.
Sources
- ASTM A564/A564M — Hot-Rolled and Cold-Finished Age-Hardening Stainless Bars and Shapes (Type 355 / UNS S35500) — ASTM International (2019)
- AMS 5743 — Steel, Corrosion Resistant, Bars and Forgings, 15.5Cr–4.5Ni–2.9Mo, Consumable Electrode Melted, SCT — SAE International (2018)
- AMS 5547 — Steel, Corrosion Resistant, Sheet, Strip and Plate, 15.5Cr–4.5Ni–2.9Mo (AM-355) — SAE International (2017)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys (semi-austenitic PH stainless) — ASM International (1990)
- MMPDS-16 — Metallic Materials Properties Development and Standardization, AM-355 sections — Battelle/FAA (2021)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.