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, شکل پذیری عالی و قابلیت جوشکاری, and high biological inertness.
درجه 1 is chosen where corrosion resistance, ساختگی, 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 تیتانیوم with tight limits on interstitial elements (اکسیژن, نیتروژن, کربن, hydrogen and minor impurities).
The material is optimized for حداکثر مقاومت در برابر خوردگی, formability and biological inertness rather than for high strength.
درجه 1 is supplied as sheet, بشقاب, نوار, لوله, 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
| سیستم استاندارد | تعیین / code | Typical name(حرف) used in industry |
| ما (ایالات متحده آمریکا) | R50250 | UNS R50250 |
| عید / عیاش (ایالات متحده آمریکا) | ASTM B265 (درجه 1) / ASME SB-265; ASTM F67 (surgical implant spec covers Grades 1–4) | CP-Ti Grade 1, درجه ASTM 1 |
| از / در (اروپا / آلمان) | Material No. 3.7025 / Ti Gr 1 | 3.7025, Ti-Grade 1 |
| GB / GB-T (چین) | TA1 (per GB/T 3620.x series) | TA1 |
| او است (ژاپن) | 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: درجه 1 is composed of >99% titanium by mass. The remaining fraction consists of carefully limited amounts of oxygen, نیتروژن, کربن, 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: درجه 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.
- مفهوم عملی: 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. فیزیکی & Mechanical Properties of CP-Ti Grade 1
| دارایی | ارزش معمولی (ساکت شده, نماینده) | واحد | یادداشت ها / dependence |
| تراکم | 4.50 | g · cm⁻³ | Nominal bulk density for CP-Ti Grade 1 — useful for mass/weight calculations. |
| مدول یانگ (مدول الاستیک, اشمیه) | 105 | معدل | Relatively low compared with steels; affects deflection and natural frequency. Little affected by cold work. |
| نسبت پواسون | 0.34 | - | Typical isotropic approximation for design. |
استحکام کششی (بیدر) |
240 - 350 | MPA | Strongly dependent on product form (ورق, نوار, لوله) and prior cold work; higher if cold-worked. |
| قدرت عملکرد (0.2% جبران کردن) | 170 - 275 | MPA | Typical annealed values near lower end; increases with cold work. Specify form/condition when ordering. |
| کشیدگی در هنگام شکست (یک ٪) | 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. |
سختی برینل (تقریبا) |
~70 - 150 | HB | تقریبی; convert from HV when needed — use hardness only as a comparative indicator. |
| مدول برشی (جف) | 40 پوند | معدل | Useful for torsion and shear calculations (G ≈ E / (2(1+حرف))). |
| هدایت حرارتی | 22 پوند | W·m-1·K-1 | Low compared with common structural metals — cutting and welding heat management important. |
| ضریب انبساط حرارتی (20-100 درجه سانتیگراد) | ~8.6 | µm·m⁻¹·K⁻¹ | Influences dimensional changes with temperature and bimetallic stresses. |
ظرفیت حرارتی خاص |
520 پوند | J·kg-1·K-1 | Relevant for thermal mass and heating calculations. |
| نقطه ذوب | 1668 | درجه سانتیگراد | Solidus/melt temperature (تقریبا). |
| مقاومت الکتریکی (در 20 درجه سانتیگراد) | ~420 | nΩ·m (0.42 μΩ · m) | Relatively high resistivity; important for electrical/EM design considerations. |
| قدرت خستگی (نشان دهنده) | ~80 - 140 | MPA | Highly dependent on surface finish, استرسهای باقیمانده, and alpha-case; use application-specific testing for critical designs. |
سختی شکستگی (k_ic, نشان دهنده) |
متوسط تا زیاد (سختی) | MPA · √m | CP-Ti Grade 1 generally shows good toughness in annealed condition; values vary with thickness and oxygen content. |
| رفتار خوردگی | عالی (passive TiO₂ film) | کیفی | Outstanding resistance in oxidizing and many chloride environments; test for aggressive reducing chemistries. |
| نفوذپذیری مغناطیسی | ≈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) ساختار بلور. Without β-stabilizing alloying elements, درجه 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, لایه اکسید چسبنده (اری) 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. - حساسیت پردازش: 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. مقاومت در برابر خوردگی و زیست سازگاری
- حفاظت منفعل: 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. - محدودیت ها: Under certain aggressive reducing conditions (به عنوان مثال, 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. - سازگاری: 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. - راهنمایی طراحی: For critical corrosion scenarios, perform application-specific corrosion testing (exposure, شکاف, galvanic pairings) rather than relying solely on general statements of “excellent corrosion resistance.”
6. ساختگی: تشکیل دهنده, ماشینکاری, and welding considerations
تشکیل دهنده
- شکل گیری سرد: درجه 1 is highly formable—deep drawing, خم, spinning and other cold forming operations are straightforward compared with higher-strength titaniums.
Springback and anisotropy should be accounted for during tooling design. - شکل گیری گرم: Performed above ambient but below temperatures where oxygen/nitrogen uptake becomes significant, or in controlled atmospheres (گاز بی حسی, خلاء).
Hot work can lower forming loads but requires strict atmosphere control to avoid surface embrittlement. - ابزار: Use polished dies and corrosion-resistant tooling to avoid contamination; lubrication and die design are important to minimize galling.
ماشینکاری
- 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
- قابلیت جوشکاری: درجه 1 welds readily by common fusion processes (TIG/GTAW, پلاسما) 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. - محافظ: Protect weld areas with inert gas (آرگون) pre- and post-flow to prevent atmospheric contamination. Avoid exposure of hot titanium to air and moisture.
- منطقه تحت تأثیر گرما (خندق): 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. - تکمیل مکانیکی: Weld undersides and beads may require grinding or machining; use suitable abrasives and avoid contamination during finishing.
7. عملیات حرارتی, درمان های سطحی, and finishing options
- عملیات حرارتی: درجه 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, پوشش (سرامامیک, hard PVD/DLC, اسپری حرارتی) or surface modifications are applied,
recognizing that the underlying oxide and substrate must be prepared correctly for adhesion. - یکپارچگی سطح: 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
- تجهیزات پردازش شیمیایی: مبدلهای حرارتی, لوله کشی, and fittings exposed to corrosive, oxidizing media where long life and low maintenance matter.
- دریایی and seawater systems: شفت های پمپ, desalination plant components, and seawater piping benefit from Grade 1’s resistance to biofouling and corrosion in chloride environments.
- Medical devices and equipment: سازهای جراحی, 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.
- یادداشت های طراحی: In structural applications where loads are significant, درجه 1 is generally replaced by higher CP grades or alloyed titanium to reduce section sizes.
درجه 1 is favored when forming complexity and corrosion resistance outweigh mechanical strength requirements.
9. مزایا & محدودیت ها
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, غیر مغناطیسی).
- چگالی کم, سبک وزن, و ثبات ابعادی بالا.
- 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 (به عنوان مثال, درجه 7 with Pd).
- Higher material cost than carbon steel and stainless steel.
10. Comparison with CP-Ti Grades 2–4
در زیر متمرکز است, engineering-grade comparison that highlights how Grade 1 differs from Grades 2–4 in chemistry, عملکرد مکانیکی, fabrication behavior and typical applications.
The data shown are نماینده (annealed/wrought conditions) and intended for material-selection guidance — always check supplier / spec certificates for guaranteed values.
| ویژگی | درجه 1 (UNS R50250) | درجه 2 (UNS R50400) | درجه 3 (UNS R50550) | درجه 4 (UNS R50700) |
| Max Fe (وزنی ٪) | 0.20 | 0.30 | 0.30 | 0.50 |
| Max C (وزنی ٪) | 0.08 | 0.08 | 0.08 | 0.08 |
| Max N (وزنی ٪) | 0.03 | 0.03 | 0.05 | 0.05 |
| Max O (وزنی ٪) | 0.18 | 0.25 | 0.35 | 0.40 |
| Max H (وزنی ٪) | 0.015 | 0.015 | 0.015 | 0.015 |
| Typical yield (ys, ساکت شده) | ≈ ≥200 MPa | ≈ ≥270 MPa | ≈ ≥350 MPa | ≈ ≥410 MPa |
| UTS معمولی (دامنه, ساکت شده) | ≈ 290–410 MPa | ≈ 390–540 MPa | ≈ 460–590 MPa | ≈ 540–740 MPa |
| ازدیاد طول معمولی (بوها, ساکت شده) | ± 30% | ± 22% | ± 18% | ± 16% |
Primary engineering tradeoff |
Maximum ductility / قابلیت تشکیل, best passive corrosion behavior | Balanced ductility + استحکام بالاتر; 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 | نقاشی عمیق, chemical/sea-water components, some medical parts | General process equipment, لوله, 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, شفت, heavier duty parts) |
11. پایان
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, درجه 1 است. است not a high-strength material, and it should not be selected where structural efficiency or load-bearing capacity is the dominant requirement.
در عوض, its value lies in reliability, تولید, and long service life in corrosive or sensitive environments.
When properly specified—especially with respect to interstitial limits, وضعیت سطح, and fabrication controls—CP-Ti Grade 1 delivers predictable performance and low life-cycle risk.
متداول
What does “CP-Ti” mean?
CP-Ti stands for تیتانیوم خالص تجاری. It refers to titanium that is not intentionally alloyed, with properties controlled mainly by trace interstitial elements (اکسیژن, نیتروژن, کربن, هیدروژن) rather than alloying additions.
Is CP-Ti Grade 1 قابل درمان با گرما?
هیچ. درجه 1 است. است 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?
درجه 1 است. است much weaker in terms of yield and tensile strength than Ti-6Al-4V and other alloyed titanium grades.
Its advantages lie in corrosion resistance, انعطاف پذیری, and ease of forming—not strength.
Why is CP-Ti Grade 1 so corrosion-resistant?
Its corrosion resistance comes from a پایدار, adherent titanium dioxide (اری) فیلم منفعل 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 مغناطیسی?
هیچ. CP-Ti Grade 1 است. است essentially non-magnetic, making it suitable for applications sensitive to magnetic fields (به عنوان مثال, certain medical and electronic uses).
