Titanium Bars

Product Description

When transitioning to titanium bars, the technical governance moves primarily to ASTM B348 (Standard Specification for Titanium and Titanium Alloy Bars and Billets).

Unlike iron-based superalloys that rely heavily on complex aging precipitation heat treatments to distinguish types, titanium bars are classified strictly by Grades that delineate whether the material is unalloyed (Commercially Pure) or altered with specific alpha/beta stabilizing elements.

Core Structural Categories

Industrial inventory for titanium round bars generally falls into two primary categories under ASTM B348:

1. Commercially Pure (CP) Titanium

Unalloyed titanium grades feature a single-phase $\alpha$ (alpha) hexagonal close-packed crystal structure. Their properties are governed by tightly controlled levels of interstitial elements like oxygen and iron.

• Grade 1 (UNS R50250): Lowest interstitial oxygen content. It yields the highest ductility and cold formability, but the lowest tensile strength.

• Grade 2 (UNS R50400): The industrial standard for global supply chains. It optimizes the balance of moderate strength, excellent weldability, and superior corrosion resistance (particularly in chloride/marine environments).

• Grade 4 (UNS R50700): Highest oxygen and iron contents allowed for CP grades, maximizing strength limits without adding metallic alloying elements.

2. Titanium Alloys

By introduction of metallic stabilizers, the microstructure shifts to a dual-phase $\alpha-\beta$ mix, drastically increasing mechanical properties via solution treating and aging if required.

• Grade 5 (Ti-6Al-4V / UNS R56400): The alpha-beta cornerstone of titanium production (accounting for roughly 50% of global usage). Stabilized by 6% Aluminum ($\alpha$-stabilizer) and 4% Vanadium ($\beta$-stabilizer). It delivers an exceptional strength-to-weight ratio, maintaining its structural integrity up to ~600°F (315°C).

• Grade 23 (Ti-6Al-4V ELI / UNS R56407): An "Extra Low Interstitial" version of Grade 5. Minimizing carbon, iron, and oxygen content significantly improves fracture toughness and ductility, which makes it standard for critical cryogenic structural components and medical implants.

Mechanical Comparison

The baseline minimum mechanical requirements established by ASTM B348 highlight the stark performance gap between unalloyed and alloyed variants:

Typical Surface Finishes

Depending on your machining allowances, ASTM B348 bars are supplied in several execution states:

• Hot Rolled / Forged (Black): Scale intact from primary reduction mills.

• Rough Turned / Peeled: Surface skin removed to clear micro-surface defects.

• Centerless Ground: High-precision OD tolerance ($\text{h8}$, $\text{h9}$, $\text{h11}$) optimized for direct feeding into CNC Swiss lathes or automatic screw machines.