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, 出色的可配合性和可焊性, and high biological inertness.
年级 1 is chosen where corrosion resistance, 织造性, 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 钛 with tight limits on interstitial elements (氧, 氮, 碳, hydrogen and minor impurities).
The material is optimized for 最大腐蚀性, formability and biological inertness rather than for high strength.
年级 1 is supplied as sheet, 盘子, 酒吧, 管子, 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
| 标准体系 | 指定 / code | Typical name(s) used in industry |
| 我们 (美国) | R50250 | UNS R50250 |
| ASTM / ASME (美国) | ASTM B265 (年级 1) / ASME SB-265; ASTM F67 (surgical implant spec covers Grades 1–4) | CP-Ti Grade 1, ASTM等级 1 |
| 从 / 在 (欧洲 / 德国) | Material No. 3.7025 / Ti Gr 1 | 3.7025, Ti-Grade 1 |
| GB / GB-T (中国) | TA1 (per GB/T 3620.x series) | TA1 |
| 他是 (日本) | 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: 年级 1 is composed of >99% titanium by mass. The remaining fraction consists of carefully limited amounts of oxygen, 氮, 碳, 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: 年级 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.
- 实际意义: 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. 身体的 & Mechanical Properties of CP-Ti Grade 1
| 性能特性 | 典型值 (退火, 代表) | 单位 | 笔记 / dependence |
| 密度 | 4.50 | g·cm⁻³ | Nominal bulk density for CP-Ti Grade 1 — useful for mass/weight calculations. |
| 杨氏模量 (弹性模量, e) | 105 | GPA | Relatively low compared with steels; affects deflection and natural frequency. Little affected by cold work. |
| 泊松比 | 0.34 | - | Typical isotropic approximation for design. |
抗拉强度 (UTS) |
240 - 350 | MPA | Strongly dependent on product form (床单, 酒吧, 管子) and prior cold work; higher if cold-worked. |
| 产生强度 (0.2% 抵消) | 170 - 275 | MPA | Typical annealed values near lower end; increases with cold work. Specify form/condition when ordering. |
| 断裂伸长率 (一个％) | 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. |
布氏硬度 (大约) |
〜70 – 150 | HB | 近似; convert from HV when needed — use hardness only as a comparative indicator. |
| 剪切模量 (g) | 〜40 | GPA | Useful for torsion and shear calculations (G ≈ E / (2(1+n))). |
| 导热率 | 〜22 | W·m⁻1·K⁻1 | Low compared with common structural metals — cutting and welding heat management important. |
| 热膨胀系数 (20–100°C) | ~8.6 | µm·m⁻¹·K⁻¹ | Influences dimensional changes with temperature and bimetallic stresses. |
比热容 |
〜520 | J·kg⁻1·K⁻1 | Relevant for thermal mass and heating calculations. |
| 熔点 | 1668 | °C | Solidus/melt temperature (大约). |
| 电阻率 (在 20 °C) | ~420 | nΩ·m (0.42 µΩ·m) | Relatively high resistivity; important for electrical/EM design considerations. |
| 疲劳强度 (指示性的) | 〜80 – 140 | MPA | Highly dependent on surface finish, 残余应力, and alpha-case; use application-specific testing for critical designs. |
断裂韧性 (k_ic, 指示性的) |
中度至高 (良好的韧性) | mpa·√m | CP-Ti Grade 1 generally shows good toughness in annealed condition; values vary with thickness and oxygen content. |
| 腐蚀行为 | 出色的 (passive TiO₂ film) | 定性的 | Outstanding resistance in oxidizing and many chloride environments; test for aggressive reducing chemistries. |
| 磁导率 | ≈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) 晶体结构. Without β-stabilizing alloying elements, 年级 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, 粘附的氧化物层 (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. - 加工灵敏度: 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. 耐腐蚀性和生物相容性
- 被动保护: 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. - 限制: Under certain aggressive reducing conditions (例如。, 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. - 生物相容性: 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. - 设计指导: For critical corrosion scenarios, perform application-specific corrosion testing (exposure, 裂缝, galvanic pairings) rather than relying solely on general statements of “excellent corrosion resistance.”
6. 制造: 成型, 加工, and welding considerations
成型
- 冷形成: 年级 1 is highly formable—deep drawing, 弯曲, spinning and other cold forming operations are straightforward compared with higher-strength titaniums.
Springback and anisotropy should be accounted for during tooling design. - 热形成: Performed above ambient but below temperatures where oxygen/nitrogen uptake becomes significant, or in controlled atmospheres (惰性气, 真空).
Hot work can lower forming loads but requires strict atmosphere control to avoid surface embrittlement. - 工具: Use polished dies and corrosion-resistant tooling to avoid contamination; lubrication and die design are important to minimize galling.
加工
- 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
- 可焊性: 年级 1 welds readily by common fusion processes (TIG/GTAW, 等离子体) 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. - 屏蔽: Protect weld areas with inert gas (氩气) pre- and post-flow to prevent atmospheric contamination. Avoid exposure of hot titanium to air and moisture.
- 热影响区 (热影响区): 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. - 机械精加工: Weld undersides and beads may require grinding or machining; use suitable abrasives and avoid contamination during finishing.
7. 热处理, 表面处理, and finishing options
- 热处理: 年级 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, 涂料 (陶瓷制品, hard PVD/DLC, 热喷雾) or surface modifications are applied,
recognizing that the underlying oxide and substrate must be prepared correctly for adhesion. - 表面完整性: 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
- 化学加工设备: 热交换器, 管道, and fittings exposed to corrosive, oxidizing media where long life and low maintenance matter.
- 海军陆战队 and seawater systems: 泵轴, desalination plant components, and seawater piping benefit from Grade 1’s resistance to biofouling and corrosion in chloride environments.
- Medical devices and equipment: 手术器械, 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.
- 设计笔记: In structural applications where loads are significant, 年级 1 is generally replaced by higher CP grades or alloyed titanium to reduce section sizes.
年级 1 is favored when forming complexity and corrosion resistance outweigh mechanical strength requirements.
9. 优点 & 限制
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, 非磁性).
- 低密度, 轻的, 和高维稳定性.
- 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 (例如。, 年级 7 with Pd).
- Higher material cost than carbon steel and stainless steel.
10. Comparison with CP-Ti Grades 2–4
下面重点介绍一下, engineering-grade comparison that highlights how Grade 1 differs from Grades 2–4 in chemistry, 机械性能, fabrication behavior and typical applications.
The data shown are 代表 (annealed/wrought conditions) and intended for material-selection guidance — always check supplier / spec certificates for guaranteed values.
| 属性 | 年级 1 (UNS R50250) | 年级 2 (UNS R50400) | 年级 3 (UNS R50550) | 年级 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 (是的, 退火) | ≈ ≥200 MPa | ≈ ≥270 MPa | ≈ ≥350 MPa | ≈ ≥410 MPa |
| 典型的悉尼科技大学 (范围, 退火) | ≈ 290–410 MPa | ≈ 390–540 MPa | ≈ 460–590 MPa | ≈ 540–740 MPa |
| 典型伸长率 (一个, 退火) | ≈ 30% | ≈ 22% | ≈ 18% | ≈ 16% |
Primary engineering tradeoff |
Maximum ductility / 形成性, best passive corrosion behavior | Balanced ductility + 更高的强度; 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 | 深图, chemical/sea-water components, some medical parts | General process equipment, 管道, 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, 轴, heavier duty parts) |
11. 结论
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, 年级 1 是 not a high-strength material, and it should not be selected where structural efficiency or load-bearing capacity is the dominant requirement.
反而, its value lies in reliability, 制造业, and long service life in corrosive or sensitive environments.
When properly specified—especially with respect to interstitial limits, 表面状况, and fabrication controls—CP-Ti Grade 1 delivers predictable performance and low life-cycle risk.
常见问题解答
What does “CP-Ti” mean?
CP-Ti stands for 商业上纯净的钛. It refers to titanium that is not intentionally alloyed, with properties controlled mainly by trace interstitial elements (氧, 氮, 碳, 氢) rather than alloying additions.
Is CP-Ti Grade 1 热处理?
不. 年级 1 是 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?
年级 1 是 much weaker in terms of yield and tensile strength than Ti-6Al-4V and other alloyed titanium grades.
Its advantages lie in corrosion resistance, 延性, and ease of forming—not strength.
Why is CP-Ti Grade 1 so corrosion-resistant?
Its corrosion resistance comes from a 稳定的, adherent titanium dioxide (tio₂) 被动电影 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 磁的?
不. CP-Ti Grade 1 是 essentially non-magnetic, making it suitable for applications sensitive to magnetic fields (例如。, certain medical and electronic uses).
