Stainless Steel 1.4938 +U (Hot rolled)
Finish state
EN 1.4938
Semi-finished bar or forging supplied without final heat treatment, to be quenched and tempered by the user.
Values for the +U condition
Other 1.4938 tempers and conditions
1.4938 is listed in 4 conditions; see the grade overview at 1.4938.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Delivery condition for machining, deep drilling and forging stock before final quench and temper. | 520 | 790 | 20 | 22 HRC | — |
+UThis page Hot rolled | Semi-finished bar or forging supplied without final heat treatment, to be quenched and tempered by the user. | 750 | 1,050 | 14 | 34 HRC | 2.8 % IACS |
+QTDefault Quenched and tempered | Standard supply condition for turbine rotors, discs, blades and high-temperature bolting up to ~550 °C. | 800 | 980 | 17 | 31 HRC | — |
Quenched and tempered at lower temperature, 1000–1200 MPa | Higher-strength temper for blades, small forgings and fasteners where strength outweighs impact toughness. | 930 | 1,100 | 14 | 36 HRC | — |
What is 1.4938 +U?
1.4938 +U is 1.4938 supplied in the +U condition — semi-finished bar or forging supplied without final heat treatment, to be quenched and tempered by the user. 1.4938 +U has a yield strength of 750 MPa (109 ksi) and a tensile strength of 1,050 MPa (152 ksi) — stronger than 93% of stainless steel grades. Elongation at break is 14% and the elastic modulus is 216 GPa (31.3 Msi). 1.4938 +U has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,420°C (2,588 °F). +QT is the default condition FabDigit quotes; +U is available on request or by drawing note.
Advantages
- High strength — 750 MPa (109 ksi), better than 93% of stainless steel grades
- High electrical conductivity — 2.8 % IACS, better than 79% of stainless steel grades
- Conducts heat well — 23 W/m·K (13.3 BTU/hr·ft·°F), better than 78% of stainless steel grades
Limitations
- Needs corrosion protection — 40/100, worse than 93% of stainless steel grades
- Limited ductility — 14%, worse than 91% of stainless steel grades
- Limited formability — 18/100, worse than 89% of stainless steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 88% of stainless steel grades
- Difficult to weld — 30/100, worse than 88% of stainless steel grades
1.4938 +U properties
Typical room-temperature values for 1.4938 +U; 23 are specific to this condition. Other listed values are 1.4938 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4938 +U has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
1.4938 +U has a yield strength of 750 MPa (109 ksi) and a tensile strength of 1,050 MPa (152 ksi) — stronger than 93% of stainless steel grades. Elongation at break is 14% and the elastic modulus is 216 GPa (31.3 Msi).
Thermal6
1.4938 +U is rated for continuous service to 400°C (752 °F). It conducts heat at 23 W/m·K (13.3 BTU/hr·ft·°F), better than 78% of stainless steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
1.4938 +U conducts electricity at 2.8 % IACS, better than 79% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), worse than 93% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4938 +U takes about 55 MJ of energy and emits 4.3 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 55%.
Manufacturability8
1.4938 +U's machinability is poor (32/100, worse than 62% of stainless steel grades); weldability poor (30/100); formability poor (18/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4938 +U
Is 1.4938 easy to machine?
Machine in the +A condition where possible; in +QT use rigid setups, sharp carbide inserts, low speed/high feed and copious coolant — work-hardens and produces stringy chips.
Can 1.4938 be welded?
Weldable with matching 12Cr filler or Ni-base consumables using 250–350 °C preheat, interpass control and a mandatory post-weld temper ~680–700 °C to restore HAZ toughness.
Can 1.4938 be formed, bent or molded?
Hot forge/upset at 1100–850 °C with slow controlled cooling; cold forming is limited to minor straightening because of high strength and low ductility.
What surface finishes work on 1.4938?
Passivate or nitride for wear/erosion; takes a fine polish, but no anodizing — thermal/erosion coatings are common on blade surfaces.
1.4938 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 | 0.1 – 0.15 | 0.12 |
| Si | ≤ 0.5 | 0.3 |
| Mn | 0.3 – 0.8 | 0.55 |
| Pimpurity | ≤ 0.03 | — |
| Simpurity | ≤ 0.02 | — |
| Cr | 11 – 12.5 | 11.8 |
| Mo | 1.5 – 2 | 1.75 |
| Niraises hardenability and toughness vs 1.4923 | 2 – 3 | 2.5 |
| Vcarbide former for creep strength | 0.25 – 0.4 | 0.3 |
| Fe | balance | — |
1.4938 +U — frequently asked
What is 1.4938 +U used for?
1.4938 +U is typically used for large steam turbine rotors, turbine shafts, high-temperature forged discs and power plant rotating components. In short: tougher than 1.4923; through-hardening rotor steel; 550 °C service limit.
What is the yield strength of 1.4938 +U?
1.4938 +U has a typical yield strength of 750 MPa (109 ksi) and a tensile strength of 1,050 MPa (152 ksi) — stronger than 93% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 1.4938 +U easy to machine?
Not especially — machinability is rated poor (32/100, worse than 62% of stainless steel grades). Machine in the +A condition where possible; in +QT use rigid setups, sharp carbide inserts, low speed/high feed and copious coolant — work-hardens and produces stringy chips.
Can 1.4938 +U be welded?
Not readily — weldability is rated poor (30/100). Weldable with matching 12Cr filler or Ni-base consumables using 250–350 °C preheat, interpass control and a mandatory post-weld temper ~680–700 °C to restore HAZ toughness.
What surface finishes work on 1.4938 +U?
Passivate or nitride for wear/erosion; takes a fine polish, but no anodizing — thermal/erosion coatings are common on blade surfaces.
Can 1.4938 +U be formed, bent or molded?
Hot forge/upset at 1100–850 °C with slow controlled cooling; cold forming is limited to minor straightening because of high strength and low ductility.
What is the maximum service temperature of 1.4938 +U?
1.4938 +U 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.
Sources
- EN 10269 — Steels and nickel alloys for fasteners with specified elevated and/or low temperature properties — CEN (2013)
- DIN 17240 / EN 10302 — Creep-resisting steels for bolting and turbine components — DIN / CEN (2008)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- 12% Cr martensitic turbine steel datasheets (Böhler, Aubert & Duval, Saarstahl) — producers (2022)
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.