316L UHP (Ultra High Purity) stainless steel bar is a double-vacuum melted modification of 316L, engineered for semiconductor ultra high purity fluid systems. FUSHUN METAL produces 316L UHP bar by VIM + VAR, with chemistry, inclusion and surface controls aligned to SEMI F20, delivering round, square and flat bar from 5 mm to 120 mm for UHP valve, gas cabinet and wet process components across the global chip making supply chain.
What Is 316L UHP Stainless Steel Bar?
316L UHP is the clean version of standard 316L (UNS S31603 / EN 1.4404), the molybdenum-bearing austenitic grade already known for pitting and intergranular corrosion resistance. What separates UHP is not composition alone but metallurgical cleanliness: impurity elements driven to trace levels, non-metallic inclusions rated to the strictest ASTM E45 classes, and a surface finished for electropolishing. FUSHUN METAL achieves this through VIM + VAR double vacuum melting, then verifies every heat with chemical analysis, inclusion rating, grain size and ultrasonic inspection under its ISO 9001 and AS9120B quality systems. Because a single metallic ion or particle shed from a fitting can contaminate 5N–6N process gas and drop wafer yield, the industry specifies 316L UHP bar for exactly this duty. The grade is produced for semiconductor fab fluid systems, UHP valve bodies, pressure sensors and welded gas delivery components.
Similar Grades of 316L UHP Bar
316L UHP is specified against the same international base grades as 316L, with SEMI F20 adding the cleanliness and surface requirements. FUSHUN METAL supplies 316L UHP bar with certificates cross-referenced across the standards below, so a single heat can be documented for ASTM, EN and JIS markets simultaneously.
| System | Grade / Designation | Standard |
|---|---|---|
| ASTM / UNS | 316L / S31603 | ASTM A276, A479 |
| EN | X2CrNiMo17-12-2 / 1.4404 | EN 10088-3 |
| EN (modified) | X2CrNiMo18-14-3 / 1.4435 | EN 10088-3 |
| JIS | SUS316L | JIS G4303 / G4304 |
| GB/T | 022Cr17Ni12Mo2 | GB/T 1220 |
| DIN | X2CrNiMo17-12-2 | DIN EN 10088-3 |
| GOST | 03Х17Н14М3 | GOST 5632 |
| Semiconductor | 316L UHP (SEMI F20) | SEMI F20; surface SEMI F19 / F60 |
Applications of 316L UHP Bar
316L UHP bar from FUSHUN METAL feeds the machining and forging of semiconductor fluid handling components where purity, weldability and electropolished finish decide performance.
Because carbon is held to 0.030% max, 316L UHP resists sensitization during orbital autogenous welding, and its low manganese suppresses weld fume, matching the weld quality demands of semiconductor installations.
316L UHP Bar Supply Range
FUSHUN METAL supplies 316L UHP bar in hot rolled and forged forms, with sizes covering prototype and production valve machining programs. All material is released with EN 10204 3.1 mill certificates and, on request, SEMI F20 compliance documentation.
| Form | Size Range |
|---|---|
| Hot rolled round bar | 5 – 120 mm (up to 300 mm on enquiry) |
| Hot rolled flat bar | Thickness 5 – 60 mm, width 20 – 200 mm |
| Forged round bar | 80 – 400 mm |
| Forged flat / square bar | Sections up to 300 x 300 mm |
Surface options include peeled and ground, centerless ground, bright annealed (BA) and electropolish-ready finish, supplied in 3 – 6 m random lengths or cut to order.
Chemical Composition of 316L UHP Bar
The composition below follows SEMI F20 and AMS UltraClean 316L requirements, with sulphur and manganese held far below the ASTM A276 maximums to protect weld quality and surface finish. FUSHUN METAL performs OES analysis per heat and records results on the certificate.
| Element | C | Si | Mn | P | S | Cr | Ni | Mo |
|---|---|---|---|---|---|---|---|---|
| UHP (SEMI F20) | ≤ 0.030 | ≤ 0.75 | ≤ 2.00 | ≤ 0.025 | ≤ 0.010 | 16.0 – 18.0 | 10.0 – 14.0 | 2.00 – 3.00 |
| ASTM A276 316L | ≤ 0.030 | ≤ 1.00 | ≤ 2.00 | ≤ 0.045 | ≤ 0.030 | 16.0 – 18.0 | 10.0 – 14.0 | 2.00 – 3.00 |
Mechanical and Quality Properties
316L UHP bar is supplied in the solution annealed condition, and FUSHUN METAL tests tensile, impact and hardness per heat under ISO 9001 / AS9120B control, adding inclusion, grain size and intergranular corrosion checks for semiconductor orders.
| Property | Condition / Standard | Requirement |
|---|---|---|
| Tensile strength | Annealed, ASTM A276 | ≥ 485 MPa |
| Yield strength (0.2%) | Annealed, ASTM A276 | ≥ 170 MPa |
| Elongation | Annealed, ASTM A276 | ≥ 40% |
| Hardness | Annealed | ≤ 217 HB |
| Inclusion rating | ASTM E45, UHP target | ≤ 1.0 / 0.5 (thin / heavy) |
| Grain size | ASTM E112 | 6 or finer |
| Intergranular corrosion | ASTM A262 Practice E | Pass |
| Surface roughness (EP) | SEMI F37 / F60 | Ra ≤ 0.25 µm, CrOx/FeOx ≥ 2.0 |
Every bar is visually and dimensionally inspected; ultrasonic testing per EN 10308 is available on request for forged sizes.
316L UHP Bar – FAQ
How does 316L UHP differ from standard 316L bar?
UHP adds double vacuum melting (VIM + VAR), tighter sulphur and manganese control, strict ASTM E45 inclusion limits, fine grain size and surface finish controls for electropolishing, while retaining the 316L composition envelope.
Why is VIM + VAR required for semiconductor grade?
VIM removes gases and volatile impurities in vacuum; VAR refines structure and further reduces inclusions. The result is minimal delta ferrite, low outgassing and a clean surface that electropolishes uniformly without particle traps.
Can 316L UHP bar be welded or electropolished?
Yes. Low carbon prevents sensitization during orbital welding, and the clean microstructure supports EP (electropolishing) and BA (bright annealing), achieving low outgassing, low adsorption and no residue.
What documentation does FUSHUN METAL provide?
EN 10204 3.1 mill certificates with heat number, full chemistry, tensile results and inclusion ratings, issued under ISO 9001 and AS9120B certified quality systems.
Do you supply small quantities for prototyping?
Yes, production runs start from 5 mm bar, and we accept trial quantities for valve makers validating new UHP designs.
