Stainless Steel SUH1
JIS SUH1
SUH1 is a JIS silicon-modified 13Cr-type martensitic heat-resisting steel (Si-modified 410) with about 0.45 %C, used where hardness must be retained at moderately elevated temperature.
Reference datasheet — SUH1 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the QT condition
SUH1 tempers and conditions
SUH1 is supplied in 6 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick for bar stock that must be machined, upset or forged before final hardening. | 450 | 760 | 22 | 20 HRC | — |
Hot rolled | Mill-supplied hot-worked bar or forged valve blanks intended for later hardening and tempering. | 600 | 900 | 16 | 31 HRC | 2.3 % IACS |
Cold drawn | Choose for close-tolerance, bright-surface bar for automatic machining before heat treatment. | 620 | 860 | 14 | 26 HRC | 2.5 % IACS |
QTDefault Quenched and tempered | Standard as-delivered valve-steel condition: best balance of hot strength, hardness and scaling resistance. | 760 | 1,000 | 18 | 31 HRC | — |
QT + Nitrided | Use for valve stems and guides needing high surface wear and scuff resistance over a tempered martensitic core. | 760 | 1,000 | 16 | 31 HRC | 2.2 % IACS |
Hardened + low-side temper 690–720 °C | Pick when valve-stem/fastener strength and wear matter more than toughness and service stays below ~650 °C. | 880 | 1,120 | 13 | 36 HRC | — |
What is SUH1?
SUH1 is a JIS silicon-modified 13Cr-type martensitic heat-resisting steel (Si-modified 410) with about 0.45 %C, used where hardness must be retained at moderately elevated temperature. In the quenched and tempered condition it provides roughly 760 MPa yield, 1000 MPa tensile, 18 % elongation and 295 HB (31 HRC) with a maximum service temperature of 750 °C, and it is supplied as hot-rolled and cold-drawn bar and forged valve blanks. Corrosion resistance is limited (score 42), the high-Si matrix is abrasive and work-hardening (machinability score 35), and fusion welding is poor. SUH3 is the usual step up when better hot corrosion resistance is required. SUH1 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,420°C (2,588 °F). SUH1 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 94% of stainless steel grades. Elongation at break is 18% and the elastic modulus is 215 GPa (31.2 Msi).
What is SUH1 used for?
- engine exhaust valves
- high-temperature fasteners
- furnace parts
Advantages
- High strength — 760 MPa (110 ksi), better than 94% of stainless steel grades
- Low embodied carbon — 3.5 kg CO₂/kg, better than 88% of stainless steel grades
- Conducts heat well — 21 W/m·K (12.1 BTU/hr·ft·°F), better than 76% of stainless steel grades
Limitations
- Low fracture toughness — 32 MPa·√m (29.1 ksi·√in), worse than 99% of stainless steel grades
- Difficult to weld — 22/100, worse than 94% of stainless steel grades
- Needs corrosion protection — 42/100, worse than 90% of stainless steel grades
- Limited formability — 18/100, worse than 89% of stainless steel grades
- Limited ductility — 18%, worse than 83% of stainless steel grades
SUH1 properties
Typical room-temperature values for SUH1-QT; bars are the position among stainless steel grades.
Physical3
SUH1 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
SUH1 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 94% of stainless steel grades. Elongation at break is 18% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
SUH1 is rated for continuous service to 750°C (1,382 °F). It conducts heat at 21 W/m·K (12.1 BTU/hr·ft·°F), better than 76% of stainless steel grades. Thermal expansion is 11 µm/m·K (6.11 µin/in·°F).
Electrical3
SUH1 conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (42/100), worse than 90% of stainless steel grades.
Sustainability4
Producing a kilogram of SUH1 takes about 52 MJ of energy and emits 3.5 kg of CO₂ — less than 76% of stainless steel grades. Typical recycled content is 60%.
Manufacturability8
SUH1's machinability is fair (35/100, better than 51% of stainless steel grades); weldability poor (22/100); formability poor (18/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. SUH1 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SUH1
Is SUH1 easy to machine?
Machine in the annealed condition with sharp carbide tooling, rigid setups and generous coolant — the high-Si matrix work-hardens and is abrasive; grinding is normal for finished valve stems.
Can SUH1 be welded?
Poor weldability: 0.45 %C martensitic steel needs 300–400 °C preheat, matching or austenitic filler, and immediate 730–780 °C temper; friction welding to an austenitic head is the production route for bimetal valves.
Can SUH1 be formed, bent or molded?
Hot forge/upset at 1050–1150 °C and cool slowly to avoid quench cracks; cold bending or heading is not practical.
SUH1 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 | 0.4 – 0.5 | 0.45 |
| Sihigh Si gives the scaling resistance | 3 – 3.5 | 3.25 |
| Mn | ≤ 0.6 | 0.35 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Ni | ≤ 0.6 | |
| Cr | 8 – 10 | 9 |
| Fe | balance |
What surface finishes work on SUH1?
No anodizing; use nitriding or chromizing/aluminizing for wear and hot-gas protection, or phosphate/oil for storage — the 9 %Cr matrix will rust in damp storage.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
How much does SUH1 cost?
SUH1 is a standard-cost stainless steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
SUH1 — frequently asked
What is SUH1 used for?
SUH1 is typically used for engine exhaust valves, high-temperature fasteners and furnace parts. In short: 750 °C valve steel; si-modified 410 martensitic; hardness retained hot.
What is the yield strength of SUH1?
SUH1 has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 94% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is SUH1 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of stainless steel grades). Machine in the annealed condition with sharp carbide tooling, rigid setups and generous coolant — the high-Si matrix work-hardens and is abrasive; grinding is normal for finished valve stems.
Can SUH1 be welded?
Not readily — weldability is rated poor (22/100). Poor weldability: 0.45 %C martensitic steel needs 300–400 °C preheat, matching or austenitic filler, and immediate 730–780 °C temper; friction welding to an austenitic head is the production route for bimetal valves.
What surface finishes work on SUH1?
No anodizing; use nitriding or chromizing/aluminizing for wear and hot-gas protection, or phosphate/oil for storage — the 9 %Cr matrix will rust in damp storage.
Can SUH1 be formed, bent or molded?
Hot forge/upset at 1050–1150 °C and cool slowly to avoid quench cracks; cold bending or heading is not practical.
What is the maximum service temperature of SUH1?
SUH1 is rated for continuous use to about 750°C (1,382 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SUH1-QT and SUH1-A?
QT is the default condition — standard as-delivered valve-steel condition: best balance of hot strength, hardness and scaling resistance. A: pick for bar stock that must be machined, upset or forged before final hardening. Yield strength is 760 MPa in QT versus 450 MPa in A.
How much does SUH1 cost?
SUH1 is a standard-cost stainless steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- JIS G 4311 — Heat-resisting steel bars — Japanese Standards Association (2019)
- GB/T 1221 — Heat-resisting steel bars (4Cr9Si2) — SAC (2007)
- EN 10090 — Valve steels and alloys for internal combustion engines (X45CrSi9-3, 1.4718) — CEN (1998)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- X45CrSi9-3 / 1.4718 valve steel datasheet — European special steel producer (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.