Stainless Steel AM-350-CRT
Supply condition
UNS S35000 · also Alloy 350, Alloy 633
CRT = cold rolled (≈50–60 % reduction) and tempered 455 °C, strip only
Ultra-high-strength thin strip for springs, diaphragms and clamps where forming is finished before heat treat.
Values for the CRT condition
Other AM-350 tempers and conditions
AM-350 is listed in 7 conditions; see the grade overview at AM-350.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Stock condition for sheet, strip and bar — formable and weldable, then hardened by the user. | 390 | 1,100 | 40 | 210 HB | — |
Equalized 745 °C, refrigerated −75 °C, tempered 540 °C | Tougher hardened condition with better ductility and slightly higher temperature capability than H850. | 970 | 1,170 | 15 | 39 HRC | — |
Double aged | Pick when sub-zero equipment is unavailable or distortion must be minimised; slightly lower strength than SCT. | 1,030 | 1,240 | 13 | 41 HRC | — |
sub-zero cooled (−75 °C) and tempered 540 °C | Use when better toughness, weld-zone ductility and ~480 °C service are needed instead of peak strength. | 1,035 | 1,240 | 14 | 42 HRC | — |
Equalized 745 °C, refrigerated −75 °C, tempered 455 °C | Highest-strength standard hardened condition for bar and forgings where ductility can be traded for strength. | 1,100 | 1,310 | 12 | 44 HRC | — |
sub-zero cooled (−75 °C) and tempered 455 °C after 930 °C conditioning | Standard high-strength sheet/strip condition (AMS 5745) for airframe and engine hardware. | 1,170 | 1,380 | 11 | 46 HRC | — |
CRTThis page Cold rolled (≈50–60 % reduction) and tempered 455 °C, strip only | Ultra-high-strength thin strip for springs, diaphragms and clamps where forming is finished before heat treat. | 1,550 | 1,720 | 4 | 49 HRC | — |
What is AM-350-CRT?
AM-350-CRT is AM-350 supplied in the CRT condition — ultra-high-strength thin strip for springs, diaphragms and clamps where forming is finished before heat treat. AM-350-CRT has a yield strength of 1,550 MPa (225 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 4% and the elastic modulus is 200 GPa (29 Msi). AM-350-CRT has a density of 7.69 g/cm³ (0.278 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,400°C (2,552 °F). A is the default condition FabDigit quotes; CRT is available on request or by drawing note.
Advantages
- High strength — 1,550 MPa (225 ksi), better than 100% of stainless steel grades
Limitations
- Limited ductility — 4%, worse than 100% of stainless steel grades
- Difficult to machine — 18/100, worse than 99% of stainless steel grades
- Limited formability — 8/100, worse than 97% of stainless steel grades
- Difficult to weld — 25/100, worse than 92% of stainless steel grades
- Needs corrosion protection — 48/100, worse than 80% of stainless steel grades
AM-350-CRT properties
Typical room-temperature values for AM-350-CRT; 12 are specific to this condition. Other listed values are AM-350 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
AM-350-CRT has a density of 7.69 g/cm³ (0.278 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
AM-350-CRT has a yield strength of 1,550 MPa (225 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 4% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
AM-350-CRT is rated for continuous service to 400°C (752 °F). It conducts heat at 16 W/m·K (9.24 BTU/hr·ft·°F), better than 58% of stainless steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
AM-350-CRT conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 80% of stainless steel grades.
Sustainability4
Producing a kilogram of AM-350-CRT takes about 58 MJ of energy and emits 4.6 kg of CO₂ — more than 66% of stainless steel grades. Typical recycled content is 25%.
Manufacturability7
AM-350-CRT's machinability is poor (18/100, worse than 99% of stainless steel grades); weldability poor (25/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AM-350-CRT
Is AM-350 easy to machine?
Machine in the annealed condition with sharp, rigid tooling, positive rake carbide, heavy feeds and flood coolant to avoid work-hardened glazing; hardened SCT/H tempers cut roughly like 45 HRC tool steel and often need grinding.
Can AM-350 be welded?
GTAW, plasma or EBW with matching AM-350 filler works well; keep heat input low and re-solution-treat plus re-harden after welding to restore full strength, since as-welded joints have austenitic, low-yield fusion zones.
Can AM-350 be formed, bent or molded?
Form, spin, draw or roll only in the annealed condition — it work-hardens rapidly by strain-induced martensite, so use intermediate anneals and generous bend radii; final shape must be set before the SCT/H cycle because hardening causes ~0.05–0.1 % dimensional change.
What surface finishes work on AM-350?
Passivate per AMS 2700/ASTM A967 after machining; takes a good mechanical polish, and can be shot-peened, black-oxided, electroplated (with low-hydrogen practice plus 190 °C bake) but is not anodized.
AM-350 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 |
|---|---|---|
| C | 0.07 – 0.11 | 0.09 |
| Mn | 0.5 – 1.25 | 0.85 |
| Si | ≤ 0.5 | 0.3 |
| Pimpurity limit | ≤ 0.04 | — |
| Simpurity limit | ≤ 0.03 | — |
| Cr | 16 – 17 | 16.5 |
| Ni | 4 – 5 | 4.3 |
| Mo | 2.5 – 3.25 | 2.75 |
| Nkey austenite stabiliser / strengthener | 0.07 – 0.13 | 0.1 |
| Fe | balance | — |
AM-350-CRT — frequently asked
What is AM-350-CRT used for?
AM-350-CRT is typically used for aircraft skin and structural sheet, jet engine parts and fasteners. In short: formable then hardenable sheet; semi-austenitic PH stainless; useful strength to 425 °C.
What is the yield strength of AM-350-CRT?
AM-350-CRT has a typical yield strength of 1,550 MPa (225 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is AM-350-CRT easy to machine?
Not especially — machinability is rated poor (18/100, worse than 99% of stainless steel grades). Machine in the annealed condition with sharp, rigid tooling, positive rake carbide, heavy feeds and flood coolant to avoid work-hardened glazing; hardened SCT/H tempers cut roughly like 45 HRC tool steel and often need grinding.
Can AM-350-CRT be welded?
Not readily — weldability is rated poor (25/100). GTAW, plasma or EBW with matching AM-350 filler works well; keep heat input low and re-solution-treat plus re-harden after welding to restore full strength, since as-welded joints have austenitic, low-yield fusion zones.
What surface finishes work on AM-350-CRT?
Passivate per AMS 2700/ASTM A967 after machining; takes a good mechanical polish, and can be shot-peened, black-oxided, electroplated (with low-hydrogen practice plus 190 °C bake) but is not anodized.
Can AM-350-CRT be formed, bent or molded?
Form, spin, draw or roll only in the annealed condition — it work-hardens rapidly by strain-induced martensite, so use intermediate anneals and generous bend radii; final shape must be set before the SCT/H cycle because hardening causes ~0.05–0.1 % dimensional change.
What is the maximum service temperature of AM-350-CRT?
AM-350-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-350-A and AM-350-CRT?
A is the default condition — stock condition for sheet, strip and bar — formable and weldable, then hardened by the user. CRT: ultra-high-strength thin strip for springs, diaphragms and clamps where forming is finished before heat treat. Yield strength is 390 MPa in A versus 1,550 MPa in CRT.
Sources
- AMS 5548 — Steel, Corrosion and Heat Resistant, Sheet, Strip and Plate 16.5Cr-4.3Ni-2.8Mo (AM-350), Annealed — SAE International (2017)
- AMS 5745 / AMS 5746 — AM-350 SCT 850 and SCT 1000 conditions — SAE International (2016)
- ASTM A693 — Precipitation-Hardening Stainless Steel Plate, Sheet and Strip (UNS S35000) — ASTM International (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- MMPDS / MIL-HDBK-5 design allowables for AM-350 sheet — Battelle Memorial Institute (2021)
- AM-350 alloy technical data — Allegheny Technologies / AK Steel (2015)
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.