Commercially pure titanium Grade 1 (CP-Ti Grade 1) is the softest and most ductile of the standard commercially pure titanium grades.
Its low interstitial impurity levels give it outstanding corrosion resistance, Відмінна формуваність та зварюваність, and high biological inertness.
Сорт 1 is chosen where corrosion resistance, складність, and biocompatibility are primary design drivers and where high structural strength is not required.
1. What is Titanium CP-Ti Grade 1?
CP-Ti Grade 1 (Commercially Pure Titanium — Grade 1) is the softest, most ductile and lowest-interstitial variant of wrought commercially pure titanium.
It is essentially unalloyed титан with tight limits on interstitial elements (кисень, азот, вуглець, hydrogen and minor impurities).
The material is optimized for Максимальна стійкість до корозії, formability and biological inertness rather than for high strength.
Сорт 1 is supplied as sheet, тарілка, бар, трубка, wire and formed components and is widely used in corrosive environments, marine service, medical devices and where deep drawing or complex forming is required.
Global standard equivalents — CP-Ti Grade 1
| Стандартна система | Призначення / code | Typical name(s) used in industry |
| Нас (США) | R50250 | UNS R50250 |
| ASTM / Asme (США) | ASTM B265 (Сорт 1) / ASME SB-265; ASTM F67 (surgical implant spec covers Grades 1–4) | CP-Ti Grade 1, ASTM клас 1 |
| З / У (Європа / Німеччина) | Material No. 3.7025 / Ti Gr 1 | 3.7025, Ti-Grade 1 |
| ГБ / GB-T (Китай) | TA1 (per GB/T 3620.x series) | TA1 |
| Він є (Японія) | TP270 / TR270 (JIS H4600 family) | JIS Class 1 / TP270 |
| DIN W-Nr. / Werkstoff-Nr. | 3.7025 | Ti1 / Ti-Grade 1 |
| Common trade / vendor names | - | CP-Ti Grade 1, Ti-1, Ti Gr 1, Ti1, TA1, TP270 |
2. Chemical composition and the role of interstitials
- Base chemistry: Сорт 1 is composed of >99% titanium by mass. The remaining fraction consists of carefully limited amounts of oxygen, азот, вуглець, hydrogen and iron.
- Interstitials control properties: Oxygen and nitrogen occupy interstitial sites in the hexagonal close-packed (hcp) α-titanium lattice.
Small increases in these interstitials produce a measurable rise in yield and tensile strength (interstitial hardening) while simultaneously reducing ductility, fracture toughness and formability.
That trade-off is central: Сорт 1 is specified with the lowest allowable interstitial content to maximize ductility and toughness. - Minor impurities: Carbon and hydrogen similarly affect embrittlement and must be limited; iron at low levels is tolerated but higher Fe can influence corrosion behavior and grain growth during processing.
- Практичний зміст: When ordering Grade 1, designers should confirm the exact composition limits required for the application, because even small variations in oxygen or nitrogen will change forming and mechanical performance.
3. Фізичний & Mechanical Properties of CP-Ti Grade 1
| Власність | Типове значення (відпалений, представник) | Одиниці | Нотатки / dependence |
| Щільність | 4.50 | G · CM⁻³ | Nominal bulk density for CP-Ti Grade 1 — useful for mass/weight calculations. |
| Модуль Юнга (Модуль пружності, Е) | 105 | GPA | Relatively low compared with steels; affects deflection and natural frequency. Little affected by cold work. |
| Коефіцієнт Пуассона | 0.34 | - | Typical isotropic approximation for design. |
Сила на розрив (UTS) |
240 - 350 | MPA | Strongly dependent on product form (аркуш, бар, трубка) and prior cold work; higher if cold-worked. |
| Похідна сила (0.2% компенсація) | 170 - 275 | MPA | Typical annealed values near lower end; increases with cold work. Specify form/condition when ordering. |
| Подовження при зламі (%) | 20 - 35 | % | High ductility in annealed sheet/plate; values fall off with increasing oxygen content or cold work. |
| Vickers hardness (HV) | ~80 – 160 | HV | Relatively low hardness among titanium products; varies with cold work and surface condition. |
Твердість за Брінеллем (прибл.) |
~70 – 150 | HB | Приблизний; convert from HV when needed — use hardness only as a comparative indicator. |
| Модуль зсуву (G) | ~ 40 | GPA | Useful for torsion and shear calculations (G ≈ E / (2(1+п.))). |
| Теплопровідність | ~ 22 | Вт·м⁻¹·K⁻¹ | Low compared with common structural metals — cutting and welding heat management important. |
| Коефіцієнт теплового розширення (20–100 ° C) | ~8.6 | µm·m⁻¹·K⁻¹ | Influences dimensional changes with temperature and bimetallic stresses. |
Питома теплоємність |
~ 520 | Дж·кг⁻¹·K⁻¹ | Relevant for thermal mass and heating calculations. |
| Температура плавлення | 1668 | ° C | Solidus/melt temperature (прибл.). |
| Питомий електричний опір (в 20 ° C) | ~420 | nΩ·m (0.42 µω · м) | Relatively high resistivity; important for electrical/EM design considerations. |
| Сила втоми (орієнтовний) | ~80 – 140 | MPA | Highly dependent on surface finish, залишкові напруги, and alpha-case; use application-specific testing for critical designs. |
Жистка перелому (K_IC, орієнтовний) |
Помірний до високого (Хороша міцність) | Mpa · √m | CP-Ti Grade 1 generally shows good toughness in annealed condition; values vary with thickness and oxygen content. |
| Корозійна поведінка | Відмінний (passive TiO₂ film) | якісний | Outstanding resistance in oxidizing and many chloride environments; test for aggressive reducing chemistries. |
| Магнітна проникність | ≈1.003 – 1.01 | - | Essentially non-magnetic — useful where low magnetic signature is needed. |
4. Microstructure and metallurgy — why CP-Ti behaves the way it does
- Single-phase α structure at room temperature: Unalloyed titanium at ambient conditions exists in the α (hcp) кристалічна структура. Without β-stabilizing alloying elements, Сорт 1 remains α across service temperatures relevant to most applications.
- Strength mechanisms: Because there are no strengthening alloy additions, Grade 1’s strength derives from lattice resistance (intrinsic), dislocation density (from cold work), grain size and interstitial content.
Cold-work increases dislocation density and therefore yield/tensile strength; anneal cycles reduce dislocation density and restore ductility. - Surface oxide: Titanium develops a thin, Прискіпливий оксидний шар (Tio₂) spontaneously in air. That passive film is a major factor in corrosion resistance.
The oxide thickness and stoichiometry are influenced by surface finish and thermal exposure during processing. - Чутливість обробки: The metal is sensitive to contamination during high-temperature processing—oxygen and nitrogen pick-up at elevated temperatures creates embrittled surface layers (“alpha case”), which degrade toughness and fatigue performance unless removed.
5. Корозійна стійкість та біосумісність
- Пасивний захист: Grade 1’s corrosion resistance stems from the rapid formation of a stable, self-healing TiO₂ passive film.
This film is chemically stable in oxidizing media and many chloride-containing environments, giving excellent resistance in seawater, many process chemistries and atmospheric exposures. - Обмеження: Under certain aggressive reducing conditions (Напр., some concentrated acids or high temperature reducing environments), localized corrosion or accelerated attack can occur.
Mechanical abrasion that removes the passive film can lead to transient corrosion until repassivation occurs. - Біосумісність: The chemically inert surface oxide, low ion release and the absence of intentional toxic alloying elements make Grade 1 highly biocompatible.
It is suitable for many long-term tissue-contact applications, including some implants and surgical instruments, provided mechanical requirements are met. - Керівництво з проектування: For critical corrosion scenarios, perform application-specific corrosion testing (exposure, щілина, galvanic pairings) rather than relying solely on general statements of “excellent corrosion resistance.”
6. Виготовлення: формування, обробка, and welding considerations
Формування
- Холодне формування: Сорт 1 is highly formable—deep drawing, згинання, spinning and other cold forming operations are straightforward compared with higher-strength titaniums.
Springback and anisotropy should be accounted for during tooling design. - Гаряче формування: Performed above ambient but below temperatures where oxygen/nitrogen uptake becomes significant, or in controlled atmospheres (інертний газ, вакуум).
Hot work can lower forming loads but requires strict atmosphere control to avoid surface embrittlement. - Інструментарія: Use polished dies and corrosion-resistant tooling to avoid contamination; lubrication and die design are important to minimize galling.
Обробка
- Cutting behavior: Despite its relative softness, titanium is more difficult to machine than many steels because of poor thermal conductivity (heat concentrates at the tool-chip interface) and the tendency to work-harden.
Chips can be long and gummy unless proper parameters are used. - Recommended approach: Use rigid setups, sharp tooling, controlled feeds, and moderate spindle speeds. Emphasize chip evacuation and tool life management.
Coolants and cutting fluid strategies should be chosen to avoid hydrogen pickup or contamination.
Welding and joining
- Зварюваність: Сорт 1 welds readily by common fusion processes (TIG/GTAW, плазма) because it is unalloyed and does not form brittle intermetallics.
Solid-state joining (friction stir, electron beam) is also feasible where geometry and cost allow. - Екранування: Protect weld areas with inert gas (аргон) pre- and post-flow to prevent atmospheric contamination. Avoid exposure of hot titanium to air and moisture.
- Зона, що постраждав від тепла (HAZ): Oxygen/nitrogen pick-up in the HAZ will embrittle the region if shielding is inadequate.
Post-weld cleaning to remove surface oxides and contamination is recommended for critical parts. - Механічна обробка: Weld undersides and beads may require grinding or machining; use suitable abrasives and avoid contamination during finishing.
7. Термічна обробка, поверхневі обробки, and finishing options
- Термічна обробка: Сорт 1 is not heat-treatable in the alloy-strengthening sense because it lacks alloying elements for phase transformation strengthening.
Thermal cycles are used only for stress relief or to restore ductility after cold working. - Surface cleaning and passivation: Typical cleaning (acid pickling, alkaline cleaning) and controlled oxidizing treatments are used to remove contaminants and restore a clean passive film.
Anodization can be used to tailor oxide thickness and appearance. - Coatings and wear treatments: For applications requiring enhanced wear resistance, покриття (керамічний, hard PVD/DLC, тепловий бризок) or surface modifications are applied,
recognizing that the underlying oxide and substrate must be prepared correctly for adhesion. - Surface integrity: Avoid processing routes that produce an embrittled ‘alpha case’.
Where alpha case forms (from high-temperature exposure in oxygen), removal by mechanical or chemical means may be necessary.
8. Typical Applications of CP-Ti Grade 1
- Хімічна обробка обладнання: Теплообмінники, трубопровід, and fittings exposed to corrosive, oxidizing media where long life and low maintenance matter.
- Морський and seawater systems: Насосні вали, desalination plant components, and seawater piping benefit from Grade 1’s resistance to biofouling and corrosion in chloride environments.
- Medical devices and equipment: Хірургічні інструменти, non-loadbearing implants and components that require inertness and biocompatibility.
- Architectural and consumer uses: Exterior architectural components, fasteners and decorative elements where corrosion resistance and appearance are important.
- Electronics and specialty parts: Components where low magnetic permeability and corrosion stability are advantageous.
- Примітки до дизайну: In structural applications where loads are significant, Сорт 1 is generally replaced by higher CP grades or alloyed titanium to reduce section sizes.
Сорт 1 is favored when forming complexity and corrosion resistance outweigh mechanical strength requirements.
9. Переваги & Обмеження
Advantages of CP-Ti Grade 1
- Highest formability and ductility among commercial titanium grades.
- Superior weldability and fabrication stability.
- Excellent inherent corrosion resistance.
- Outstanding biocompatibility (non‑toxic, немагнітний).
- Низька щільність, легкий, і висока розмірна стабільність.
- Stable performance at cryogenic and moderate temperatures.
Limitations of CP-Ti Grade 1
- Low mechanical strength; unsuitable for high‑load structural parts.
- Not hardenable by heat treatment (only work hardening).
- Limited use in strong reducing acids without alloy modification (Напр., Сорт 7 with Pd).
- Higher material cost than carbon steel and stainless steel.
10. Comparison with CP-Ti Grades 2–4
Нижче наведено фокус, engineering-grade comparison that highlights how Grade 1 differs from Grades 2–4 in chemistry, механічні показники, fabrication behavior and typical applications.
The data shown are представник (annealed/wrought conditions) and intended for material-selection guidance — always check supplier / spec certificates for guaranteed values.
| Атрибут | Сорт 1 (UNS R50250) | Сорт 2 (UNS R50400) | Сорт 3 (UNS R50550) | Сорт 4 (UNS R50700) |
| Max Fe (WT%) | 0.20 | 0.30 | 0.30 | 0.50 |
| Max C (WT%) | 0.08 | 0.08 | 0.08 | 0.08 |
| Max N (WT%) | 0.03 | 0.03 | 0.05 | 0.05 |
| Max O (WT%) | 0.18 | 0.25 | 0.35 | 0.40 |
| Max H (WT%) | 0.015 | 0.015 | 0.015 | 0.015 |
| Typical yield (Ys, відпалений) | ≈ ≥200 MPa | ≈ ≥270 MPa | ≈ ≥350 MPa | ≈ ≥410 MPa |
| Типовий UTS (діапазон, відпалений) | ≈ 290–410 MPa | ≈ 390–540 MPa | ≈ 460–590 MPa | ≈ 540–740 MPa |
| Типове видовження (A, відпалений) | ≈ 30% | ≈ 22% | ≈ 18% | ≈ 16% |
Primary engineering tradeoff |
Maximum ductility / Формування, best passive corrosion behavior | Balanced ductility + вища сила; most widely used CP grade | Higher strength for more structural use while retaining corrosion resistance | Highest strength among CP grades (strain-hardenable); reduced formability |
| Common uses | Глибокий малюнок, chemical/sea-water components, some medical parts | General process equipment, трубки, structural components with moderate loads | Components requiring higher allowable stresses, heavier duty process parts | Where higher strength in CP titanium is needed (strain-hardened fasteners, вали, heavier duty parts) |
11. Висновок
Titanium CP-Ti Grade 1 represents the purest and most formable form of commercially pure titanium.
Its defining characteristics—very low interstitial content, single-phase α microstructure, and a stable, self-healing oxide film—give it exceptional corrosion resistance, outstanding ductility, and excellent biocompatibility.
These attributes make Grade 1 a preferred material for chemically aggressive environments, seawater exposure, medical and biomedical uses, and applications requiring deep drawing or complex cold forming.
From an engineering perspective, Сорт 1 є not a high-strength material, and it should not be selected where structural efficiency or load-bearing capacity is the dominant requirement.
Натомість, its value lies in reliability, виробництво, and long service life in corrosive or sensitive environments.
When properly specified—especially with respect to interstitial limits, стан поверхні, and fabrication controls—CP-Ti Grade 1 delivers predictable performance and low life-cycle risk.
Поширені запитання
What does “CP-Ti” mean?
CP-Ti stands for Комерційно чистий титан. It refers to titanium that is not intentionally alloyed, with properties controlled mainly by trace interstitial elements (кисень, азот, вуглець, водень) rather than alloying additions.
Is CP-Ti Grade 1 теплообробка?
Ні. Сорт 1 є not heat-treatable for strengthening because it is unalloyed. Heat treatments are used only for stress relief or annealing to restore ductility after cold working.
Is Grade 1 stronger or weaker than titanium alloys like Ti-6Al-4V?
Сорт 1 є much weaker in terms of yield and tensile strength than Ti-6Al-4V and other alloyed titanium grades.
Its advantages lie in corrosion resistance, пластичність, and ease of forming—not strength.
Why is CP-Ti Grade 1 so corrosion-resistant?
Its corrosion resistance comes from a конюшня, adherent titanium dioxide (Tio₂) пасивний фільм that forms instantly in air or aqueous environments.
This film is self-healing and protects the metal in many oxidizing and chloride-containing environments.
Is CP-Ti Grade 1 магнітний?
Ні. CP-Ti Grade 1 є essentially non-magnetic, making it suitable for applications sensitive to magnetic fields (Напр., certain medical and electronic uses).
