TITANIUM UNS

1. Introduction to Titanium Fasteners in Critical Engineering Applications

Titanium fasteners represent a specialized category of high-performance fastening systems engineered for environments where corrosion resistance, high strength-to-weight ratio, fatigue endurance, and temperature stability are critical design requirements.

Within the industrial fastener sector, the most commonly specified titanium grades for bolting applications include:

UNS Number	Titanium Grade	Common Designation
UNS R50400	Grade 2 Titanium	Commercially Pure Titanium
UNS R56400	Grade 5 Titanium	Ti-6Al-4V
UNS R52400	Grade 7 Titanium	Ti-Pd Alloy

These materials are extensively used across:

• Offshore structures
• Oil & gas production systems
• LNG facilities
• Petrochemical plants
• Desalination systems
• Aerospace equipment
• Power generation facilities
• Marine engineering
• Chemical process industries
• High-purity manufacturing systems

SM Fasteners manufactures precision titanium fasteners under controlled quality systems compliant with ISO 9001 requirements and supports global EPC, OEM, maintenance, and industrial procurement projects requiring corrosion-resistant fastening solutions.

2. Titanium Fasteners within Modern Engineering Design

Fasteners are not merely mechanical connectors.

In engineered assemblies, they function as:

• Structural load transfer elements
• Vibration-resistant joint systems
• Pressure-retaining components
• Fatigue-critical members
• Corrosion-resistant joining systems

Failure of a single fastener may compromise:

• Pressure vessel integrity
• Pipeline systems
• Offshore structures
• Rotating equipment
• Turbine assemblies
• Heat exchangers
• Critical process equipment

Titanium alloys are selected when conventional stainless steels or nickel alloys become either:

• Too heavy
• Insufficiently corrosion resistant
• Susceptible to chloride attack
• Economically unsuitable over lifecycle cost

3. Technical Definition of Titanium Fasteners

Titanium fasteners are externally or internally threaded mechanical components manufactured from titanium or titanium alloys and designed to generate clamping force through controlled preload.

Common products include:

• Hex bolts
• Heavy hex bolts
• Socket head cap screws
• Stud bolts
• Threaded rods
• Hex nuts
• Heavy hex nuts
• Lock nuts
• Flat washers
• Spring washers
• Anchor bolts
• U-bolts
• Custom engineered fasteners

4. Why Titanium is Used for Fasteners

Titanium possesses a unique combination of properties rarely found in other engineering materials.

Property	Titanium Advantage
Density	4.51 g/cm³
Strength-to-weight ratio	Exceptional
Seawater resistance	Outstanding
Chloride resistance	Excellent
Fatigue resistance	High
Non-magnetic behavior	Excellent
Galvanic compatibility	Favorable
Biocompatibility	Excellent
Temperature capability	Up to 600°C depending on grade

Compared with stainless steel:

• Approximately 45% lighter
• Comparable or superior corrosion resistance
• Excellent fatigue performance
• Longer service life in marine environments

5. UNS R50400 (Titanium Grade 2)

Material Overview

UNS R50400 is commercially pure titanium containing minimal alloying elements.

Typical Chemical Composition

Element	Maximum %
Nitrogen	0.03
Carbon	0.08
Hydrogen	0.015
Iron	0.30
Oxygen	0.25
Titanium	Balance

Characteristics

• Excellent seawater resistance
• Superior crevice corrosion resistance
• Outstanding weldability
• Excellent ductility
• Good formability
• Moderate strength

Typical Applications

• Heat exchangers
• Desalination plants
• Chemical processing
• Marine structures
• Pollution control equipment

6. UNS R56400 (Titanium Grade 5 – Ti-6Al-4V)

Material Overview

Grade 5 titanium is the most widely used titanium alloy worldwide.

Typical Chemical Composition

Element	%
Aluminum	5.5–6.75
Vanadium	3.5–4.5
Iron	≤0.40
Oxygen	≤0.20
Titanium	Balance

Characteristics

• High tensile strength
• Excellent fatigue resistance
• High load-bearing capability
• Good corrosion resistance
• Aerospace-grade performance

Typical Applications

• Offshore systems
• Aerospace structures
• Turbine equipment
• Pressure-retaining assemblies
• High-strength bolting systems

7. UNS R52400 (Titanium Grade 7)

Material Overview

Grade 7 titanium incorporates palladium additions to improve corrosion resistance.

Typical Chemical Composition

Element	%
Palladium	0.12–0.25
Iron	≤0.30
Oxygen	≤0.25
Titanium	Balance

Characteristics

• Superior acid resistance
• Enhanced crevice corrosion resistance
• Improved reducing acid performance
• Exceptional chemical process compatibility

Typical Applications

• Chloride processing
• Chemical reactors
• Acid handling equipment
• Offshore chemical systems

8. Functional Role of Titanium Fasteners

Titanium fasteners primarily generate preload.

This preload:

• Compresses joint members
• Creates frictional resistance
• Prevents separation
• Resists cyclic loading
• Maintains sealing integrity

The fastener itself should ideally never experience significant shear loading.

Instead:

Friction between clamped surfaces carries the load.

9. Fundamentals of Load Mechanics

A bolted joint behaves as an elastic system.

Two springs exist:

Spring 1 – Fastener

The bolt stretches elastically.

Spring 2 – Joint Members

The clamped materials compress elastically.

The balance between these two elastic elements determines:

• Joint stability
• Fatigue life
• Load distribution
• Resistance to loosening

10. Fastener Preload Theory

Preload is the tensile force intentionally induced during tightening.

Preload Equation

$$F_p = k \times A_t \times S_p$$

Where:

Symbol	Meaning
Fp	Preload force
At	Tensile stress area
Sp	Proof strength
k	Utilization factor

Typical utilization:

70–80% of proof load

11. Importance of Preload

Proper preload provides:

Benefit	Engineering Effect
Joint stability	Prevents separation
Fatigue resistance	Reduces stress cycling
Leak prevention	Maintains gasket compression
Vibration resistance	Minimizes loosening
Load sharing	Distributes external loads

Insufficient preload remains one of the most common causes of fastener failure across industrial installations.

12. Clamping Force Generation

When tightening a titanium bolt:

Torque applied → Thread friction → Bearing friction → Bolt elongation → Clamp load

Only a small portion of torque becomes useful preload.

Typical distribution:

Torque Energy Distribution	Approx. %
Thread friction	40
Under-head friction	50
Useful preload	10

Therefore lubrication control becomes critical.

13. Torque–Tension Relationship

The basic engineering relationship:

$$T = KFD$$

Where:

Symbol	Definition
T	Torque
K	Nut factor
F	Preload
D	Nominal diameter

This relationship forms the basis of all bolted-joint design calculations.

14. Nut Factor Influence

Nut factor varies depending upon:

• Surface finish
• Lubrication
• Thread condition
• Coating type
• Material pairing

Condition	Typical K Value
Dry Titanium	0.25–0.35
Lubricated Titanium	0.15–0.22
MoS₂ Lubricated	0.12–0.18
Anti-Galling Compound	0.15–0.20

Titanium fasteners require controlled lubrication due to galling susceptibility.

15. Thread Engagement Principles

Adequate thread engagement ensures that:

• Bolt strength exceeds thread stripping strength
• Load distributes uniformly
• Joint integrity remains intact

Recommended engagement:

Material Combination	Minimum Engagement
Titanium into Titanium	1.5D
Titanium into Steel	1.0D
Titanium into Aluminum	2.0D
Titanium into Cast Materials	2.0–2.5D

Where D = nominal diameter.

16. Load Distribution Along Threads

Load is not equally distributed.

Approximate distribution:

Thread Position	Load Carried
First thread	34%
Second thread	23%
Third thread	16%
Fourth thread	11%
Remaining threads	16%

This explains why thread quality is critical for titanium fasteners.

17. Tensile Loading Behavior

Titanium fasteners are particularly effective under tensile loading.

Key advantages include:

• High elastic strain capability
• Excellent fatigue endurance
• Low density
• Corrosion resistance

Typical tensile applications:

• Pressure vessels
• Flange assemblies
• Structural connections
• Offshore modules

18. Shear Loading Considerations

Bolts should not be intentionally designed to carry primary shear loads unless specifically engineered.

Preferred approach:

• Generate sufficient preload
• Utilize friction grip
• Prevent slip between components

Direct shear loading increases:

• Fatigue risk
• Fretting
• Joint relaxation

19. Fatigue Performance of Titanium uns Fasteners

Fatigue failures originate from:

• Thread roots
• Surface defects
• Corrosion pits
• Improper preload

Titanium alloys demonstrate excellent fatigue resistance due to:

• High strength-to-weight ratio
• Stable oxide film
• Corrosion resistance

Applications benefiting from fatigue resistance:

• Rotating machinery
• Offshore structures
• Aerospace systems
• Transportation infrastructure

20. Joint Relaxation Mechanisms

Preload reduction can occur through:

Cause	Effect
Embedment	Surface flattening
Creep	Long-term deformation
Gasket compression	Clamp loss
Thermal cycling	Expansion mismatch
Vibration	Loosening

Titanium joints require preload verification in critical applications.

21. Differential Thermal Expansion

Titanium exhibits lower thermal expansion than many alloys.

Material	Expansion Coefficient µm/m°C
Titanium	8.6
Carbon Steel	12
Stainless Steel	17
Aluminum	23

This influences preload retention during temperature cycling.

22. Joint Design Principles for Titanium Fasteners

Effective joint design requires balancing:

• Strength
• Corrosion resistance
• Accessibility
• Inspection capability
• Service environment

Design objectives include:

1. Maintaining preload
2. Avoiding slip
3. Preventing fatigue
4. Minimizing corrosion
5. Facilitating maintenance

23. Friction Grip Joint Design

Preferred for:

• Structural steel
• Offshore modules
• Dynamic equipment

Advantages:

• No bolt shear
• Superior fatigue life
• Better vibration resistance

Titanium fasteners provide significant benefits in aggressive marine environments.

24. Bearing-Type Joint Design

Used when:

• Minor movement is acceptable
• Load transfer occurs through contact surfaces
• Structural simplicity is required

Common applications:

• Equipment supports
• Mechanical assemblies
• Utility structures

25. Design Factors Affecting Fastener Selection

Engineers should evaluate:

Parameter	Consideration
Tensile load	Static & dynamic
Temperature	Maximum operating range
Corrosion exposure	Chlorides, acids, seawater
Inspection access	Maintenance requirements
Weight reduction	Design optimization
Service life	Lifecycle cost
Regulatory requirements	Industry standards

26. Engineering Advantages Offered by SM Fasteners

SM Fasteners supports titanium fastening requirements through:

• Precision manufacturing systems
• ISO 9001 quality management practices
• UKAF-certified quality framework
• MSME-recognized manufacturing operations
• Custom-engineered fastener production
• Standard and special thread configurations
• Titanium, nickel alloy, duplex stainless steel, and PEEK fastening solutions
• Full material traceability and inspection documentation for industrial procurement requirements

27. Titanium Fastener Product Portfolio

Titanium fasteners are manufactured in a broad range of configurations to satisfy structural, pressure-containing, rotating equipment, offshore, marine, aerospace, and chemical process industry requirements.

Selection of fastener geometry directly affects:

• Load transfer capability
• Assembly accessibility
• Torque transmission
• Fatigue resistance
• Inspection capability
• Corrosion performance
• Maintenance intervals

SM Fasteners manufactures standard and custom titanium fasteners in UNS R50400, UNS R56400, and UNS R52400 materials according to international standards and project-specific specifications.

28. Major Titanium Fastener Categories

Product Type	Primary Function
Hex Bolts	General structural fastening
Heavy Hex Bolts	High-load joints
Hex Cap Screws	Machinery assembly
Socket Head Cap Screws	High-strength compact installations
Stud Bolts	Flanged joints
Fully Threaded Studs	Pressure equipment
Threaded Rods	Structural anchoring
Hex Nuts	Standard mating component
Heavy Hex Nuts	High preload applications
Lock Nuts	Anti-vibration fastening
Flat Washers	Load distribution
Spring Washers	Resistance to loosening
U-Bolts	Pipe support systems
Eye Bolts	Lifting and rigging
Anchor Bolts	Concrete anchorage
Custom Fasteners	OEM requirements

29. Hex Bolt Geometry

Hex bolts remain the most widely used titanium fastening system.

Characteristics

• External hexagonal drive
• Full or partial thread
• High torque capability
• Easy inspection
• Compatible with standard tooling

Common Standards

• ISO 4014
• ISO 4017
• DIN 931
• DIN 933
• ASTM F468
• BS 3692

30. Heavy Hex Bolts

Heavy hex bolts feature:

• Larger bearing surface
• Increased wrenching area
• Higher preload capability
• Improved fatigue resistance

Applications include:

• Offshore structures
• Petrochemical equipment
• Pressure vessels
• LNG facilities

31. Socket Head Cap Screws

Standard references:

• ISO 4762
• DIN 912

Characteristics:

Feature	Benefit
Cylindrical head	Compact design
Internal hex drive	High torque transmission
Precise alignment	Improved assembly
Smaller footprint	Limited-space installations

Typical applications:

• Pumps
• Compressors
• Turbines
• Instrumentation

32. Stud Bolts

Stud bolts are preferred in:

• Pressure-retaining joints
• Heat exchangers
• Pipe flanges
• Valves

Advantages:

• Uniform preload distribution
• Easier maintenance
• Reduced thread wear in equipment

Applicable standards:

• ASTM A193 principles
• ASME B16.5 flange systems
• DIN 976
• BS 4439

33. Threaded Rods

Threaded rods provide:

• Continuous thread engagement
• Adjustable assembly
• Structural anchoring capability

Applications:

• Pipe supports
• Structural steel
• Equipment foundations
• Suspension systems

34. Titanium Nuts

Common nut configurations include:

Hex Nuts

• ISO 4032
• DIN 934

Heavy Hex Nuts

• ASTM-compatible designs
• Structural joints

Lock Nuts

• Prevailing torque type
• Nylon insert type
• All-metal lock nuts

35. Washer Configurations

Washers serve multiple engineering purposes.

Flat Washers

Functions:

• Load distribution
• Surface protection
• Reduction of embedment

Standards:

• ISO 7089
• DIN 125
• DIN 9021

Spring Washers

Functions:

• Increased resistance to loosening
• Compensation for minor relaxation

Standards:

• DIN 127

36. U-Bolts

Titanium U-bolts are used where corrosion resistance is critical.

Applications:

• Offshore piping
• Seawater systems
• Desalination plants
• Marine structures

Manufactured according to:

• Project drawings
• MSS standards
• Client specifications

37. Eye Bolts and Lifting Fasteners

Titanium eye bolts are selected when:

• Weight reduction is critical
• Corrosion resistance is required
• Magnetic interference must be minimized

Typical industries:

• Aerospace
• Marine
• Scientific equipment

38. Anchor Bolt Systems

Titanium anchor bolts provide:

• Long service life
• Resistance to chloride attack
• Reduced maintenance costs

Used in:

• Coastal infrastructure
• Offshore platforms
• Chemical facilities

39. Custom Titanium Fasteners

SM Fasteners supports:

• Special head designs
• Non-standard dimensions
• Proprietary thread forms
• High-temperature assemblies
• OEM-specific components

Custom manufacturing includes:

• CNC machining
• Precision forging
• Thread rolling
• Special inspection programs

40. Dimensional Logic of Fasteners

Every fastener dimension affects mechanical performance.

Critical dimensions include:

Parameter	Influence
Diameter	Tensile capacity
Pitch	Load distribution
Thread length	Engagement strength
Head height	Torque capability
Across flats	Tool interface
Bearing surface	Contact stress

41. Nominal Diameter System

Metric fasteners are designated by:

Example:

M16 × 2.0 × 100

Where:

Element	Meaning
M	Metric thread
16	Diameter (mm)
2.0	Pitch (mm)
100	Length (mm)

42. Standard Metric Diameter Range

Designation	Diameter (mm)
M3	3
M4	4
M5	5
M6	6
M8	8
M10	10
M12	12
M16	16
M20	20
M24	24
M30	30
M36	36
M42	42
M48	48
M56	56
M64	64

SM Fasteners can manufacture larger diameters based on project requirements.

43. Standard Metric Coarse Thread Pitch Table

Size	Pitch (mm)
M6	1.0
M8	1.25
M10	1.5
M12	1.75
M16	2.0
M20	2.5
M24	3.0
M30	3.5
M36	4.0
M42	4.5
M48	5.0

44. Metric Fine Thread Series

Fine threads are selected for:

• Vibration resistance
• Limited engagement lengths
• Precision assemblies

Size	Fine Pitch (mm)
M10	1.25
M12	1.50
M16	1.50
M20	1.50
M24	2.00
M30	2.00

45. Hex Bolt Dimensional Specification Table

ISO 4014 / DIN 931 (Typical)

Size	Across Flats (mm)	Head Height (mm)
M6	10	4
M8	13	5.3
M10	16	6.4
M12	18	7.5
M16	24	10
M20	30	12.5
M24	36	15
M30	46	18.7
M36	55	22.5

46. Preferred Length Series

Standard manufacturing lengths:

Diameter	Length Range
M6–M12	10–200 mm
M16–M24	30–300 mm
M30–M48	50–500 mm
Above M48	Custom

47. Thread Forms Used in Titanium Fasteners

Titanium fasteners are supplied in multiple thread systems.

48. Metric Thread Standard

Applicable standards:

• ISO 68
• ISO 261
• ISO 262
• ISO 965

Thread angle:

60°

Most common globally.

49. UNC Thread Standard

Unified National Coarse

Applicable standards:

• ASME B1.1

Thread angle:

60°

Widely used in:

• Oil & gas
• North American OEM equipment
• Heavy machinery

50. UNF Thread Standard

Unified National Fine

Advantages:

• Better preload control
• Improved fatigue performance
• Higher tensile stress area

Applications:

• Aerospace
• Rotating equipment
• Precision assemblies

51. BSW Thread Standard

British Standard Whitworth

Applicable standard:

• BS 84

Thread angle:

55°

Found in:

• Legacy infrastructure
• Railways
• Older industrial equipment

52. BSF Thread Standard

British Standard Fine

Characteristics:

• Fine pitch
• Improved vibration resistance
• Legacy UK installations

53. Thread Standards & Tolerances Table

Thread Type	Standard	Angle	Tolerance Class
Metric	ISO 965	60°	6g / 6H
UNC	ASME B1.1	60°	2A / 2B
UNF	ASME B1.1	60°	2A / 2B
BSW	BS 84	55°	Standard Whitworth
BSF	BS 84	55°	Standard Fine

54. External Thread Tolerances

Common classes:

Class	Application
6g	General engineering
4g6g	Precision assemblies
8g	Loose fit applications

55. Internal Thread Tolerances

Class	Application
6H	Standard nuts
5H	Close fit
7H	Free running fit

56. Titanium Fastener Standards

ASTM Standards

Standard	Description
ASTM F467	Titanium Nuts
ASTM F468	Titanium Bolts & Screws
ASTM B348	Titanium Bar Stock
ASTM B381	Titanium Forgings
ASTM E8	Tensile Testing
ASTM E18	Hardness Testing

57. ISO Standards

Standard	Scope
ISO 4014	Hex Bolts
ISO 4017	Fully Threaded Hex Bolts
ISO 4032	Hex Nuts
ISO 4762	Socket Head Screws
ISO 7089	Flat Washers
ISO 965	Thread Tolerances

58. DIN Standards

Standard	Description
DIN 931	Hex Bolt
DIN 933	Full Thread Hex Bolt
DIN 934	Hex Nut
DIN 912	Socket Head Screw
DIN 125	Flat Washer
DIN 127	Spring Washer
DIN 975	Threaded Rod
DIN 976	Stud Bolts

59. British Standards

Standard	Description
BS 3692	Metric Fasteners
BS 4190	ISO Metric Bolts
BS 4320	Washers
BS 1768	Hex Nuts
BS 84	Whitworth Threads

60. Interchangeability Considerations

Engineers must verify:

• Thread form compatibility
• Tolerance class
• Strength requirements
• Surface finish
• Nut compatibility

Improper interchangeability can lead to:

• Galling
• Thread stripping
• Loss of preload
• Fatigue failures

61. Galling Prevention Through Geometry Selection

Titanium exhibits a tendency toward adhesive wear.

Recommended practices:

• Rolled threads
• Lubricated assembly
• Fine surface finish
• Controlled torque
• Dissimilar nut materials when appropriate

62. Engineering Design Considerations for Titanium Fastener Geometry

Selection should consider:

Design Factor	Recommendation
High preload	Heavy hex bolts
Limited space	Socket head screws
Pressure joints	Stud bolts
Marine exposure	Grade 2 or Grade 7
High strength	Grade 5
Corrosive chemicals	Grade 7
Weight reduction	Titanium over stainless steel

63. Dimensional Consistency and Quality Assurance

For industrial projects, dimensional conformity is verified through:

• GO/NO-GO gauges
• Thread ring gauges
• Thread plug gauges
• Coordinate measurement systems
• Digital metrology equipment

Under SM Fasteners’ ISO 9001 quality framework, dimensional verification is integrated into production control and final inspection processes to ensure compliance with customer specifications and applicable international standards.

64. Titanium Material Grades for Industrial Fasteners

Material selection is the single most important engineering decision affecting fastener performance, service life, corrosion resistance, maintenance frequency, and total lifecycle cost.

For titanium fasteners, UNS R50400, UNS R56400, and UNS R52400 represent three distinct performance categories:

UNS Grade	Titanium Grade	Type
R50400	Grade 2	Commercially Pure Titanium
R56400	Grade 5	Ti-6Al-4V Alloy
R52400	Grade 7	Ti-Pd Corrosion Resistant Alloy

Each grade offers unique advantages depending on mechanical loading and environmental exposure.

65. Material Selection Criteria for EPC Projects

Engineers should evaluate the following parameters before selecting titanium fasteners:

Selection Parameter	Engineering Impact
Tensile Load	Determines strength requirement
Fatigue Loading	Influences alloy selection
Corrosion Exposure	Defines grade suitability
Temperature	Impacts material stability
Weight Reduction	May justify titanium use
Maintenance Access	Influences lifecycle decisions
Service Life	Total ownership cost
Industry Specification	Compliance requirements

66. Titanium Grade Comparison Table

Material Selection Matrix

Property	Grade 2 (R50400)	Grade 5 (R56400)	Grade 7 (R52400)
Density (g/cm³)	4.51	4.43	4.51
Tensile Strength (MPa)	345	895	345
Yield Strength (MPa)	275	828	275
Ductility (%)	20	10	20
Seawater Resistance	Excellent	Excellent	Excellent
Acid Resistance	Very Good	Good	Outstanding
Crevice Corrosion Resistance	Excellent	Good	Exceptional
Fatigue Strength	Good	Excellent	Good
Weldability	Excellent	Moderate	Excellent
Relative Cost	Medium	High	Highest

67. Mechanical Properties Table

ASTM F468/F467 Titanium Fasteners

Property	Grade 2	Grade 5	Grade 7
Ultimate Tensile Strength (MPa)	345	895	345
Yield Strength (MPa)	275	828	275
Elongation (%)	20	10	20
Reduction of Area (%)	30	25	30
Elastic Modulus (GPa)	103	114	103
Hardness (HV)	145–180	320–380	145–180

68. Strength-to-Weight Advantage

One of titanium’s primary engineering advantages is its exceptional strength-to-weight ratio.

Material	Density (g/cm³)	Typical UTS (MPa)
Carbon Steel	7.85	400–800
Stainless Steel 316	8.00	515
Duplex S32205	7.80	620
Titanium Grade 2	4.51	345
Titanium Grade 5	4.43	895

This makes titanium particularly attractive for:

• Offshore topsides
• Aerospace structures
• LNG modules
• Weight-sensitive rotating equipment

69. Corrosion Resistance Comparison

Environmental Compatibility Table

Environment	Grade 2	Grade 5	Grade 7
Atmospheric Exposure	Excellent	Excellent	Excellent
Marine Atmosphere	Excellent	Excellent	Excellent
Seawater Immersion	Excellent	Excellent	Excellent
Chloride Solutions	Excellent	Good	Excellent
Wet Chlorine	Good	Moderate	Excellent
Nitric Acid	Excellent	Very Good	Excellent
Sulfuric Acid	Moderate	Moderate	Excellent
Organic Acids	Excellent	Excellent	Excellent
Desalination Plants	Excellent	Excellent	Excellent
Offshore Platforms	Excellent	Excellent	Excellent

70. Titanium in Seawater Service

Titanium is widely regarded as one of the most seawater-resistant engineering materials available.

Advantages include:

• Immunity to pitting corrosion
• Resistance to crevice corrosion
• No chloride stress corrosion cracking
• Long-term biofouling resistance
• Stable passive oxide film

Common applications:

• Offshore structures
• Seawater cooling systems
• Marine pumps
• Heat exchangers
• Shipbuilding

71. Titanium in Acidic Environments

Grade selection becomes critical in chemical process industries.

Recommended Grades

Acid Environment	Preferred Grade
Nitric Acid	Grade 2
Acetic Acid	Grade 2
Organic Acids	Grade 2
Sulfuric Acid	Grade 7
Chloride Acid Systems	Grade 7
Mixed Acid Service	Grade 7

72. Titanium Fasteners in Sour Service

Titanium is generally resistant to hydrogen sulfide environments.

However, project specifications should verify compliance with:

• NACE MR0175
• ISO 15156
• End-user requirements

Critical factors:

• Hardness limitations
• Environmental severity
• Chloride concentration
• Partial pressure of H₂S

73. Temperature Capability

Service Temperature Limits

Grade	Recommended Continuous Service
Grade 2	Up to 315°C
Grade 5	Up to 400°C
Grade 7	Up to 315°C

For elevated temperature applications, detailed engineering evaluation is recommended.

74. Titanium Fastener Failure Mechanisms

Proper grade selection helps prevent common failures.

Major Failure Modes

• Fatigue failure
• Galling
• Over-tightening
• Thread stripping
• Stress corrosion attack
• Fretting wear
• Hydrogen absorption
• Joint relaxation

75. Galling – The Most Important Titanium Fastener Concern

Titanium has a natural tendency toward adhesive wear.

Galling Occurs When:

• Similar metals slide together
• Surface asperities weld together
• High contact pressure exists
• Lubrication is absent

Prevention Methods

• Use anti-seize compounds
• Reduce installation speed
• Apply controlled lubrication
• Utilize rolled threads
• Avoid repeated assembly cycles

76. Importance of Anti-Galling Lubrication

Recommended lubricants include:

Lubricant Type	Application
Molybdenum Disulfide	High-load assemblies
Nickel Anti-Seize	High temperature
PTFE-Based Compound	Chemical service
Graphite-Free Lubricant	Sensitive applications

Proper lubrication significantly improves preload consistency.

77. Heat Treatment of Titanium Fasteners

Heat treatment is performed to optimize:

• Mechanical strength
• Ductility
• Fatigue resistance
• Microstructural stability

Not all titanium grades require the same heat treatment process.

78. Heat Treatment of Grade 2 (UNS R50400)

Grade 2 is commercially pure titanium.

Typical processing:

• Stress relieving
• Annealing

Purpose:

• Improve dimensional stability
• Reduce residual stresses
• Enhance machinability

79. Heat Treatment of Grade 5 (UNS R56400)

Grade 5 titanium responds significantly to thermal processing.

Typical Heat Treatments

Process	Purpose
Annealing	Improve ductility
Solution Treatment	Strength optimization
Aging	Increased mechanical properties
Stress Relieving	Residual stress reduction

80. Heat Treatment of Grade 7 (UNS R52400)

Heat treatment objectives:

• Maintain corrosion resistance
• Stabilize microstructure
• Improve dimensional consistency

Typically supplied in:

• Annealed condition
• Stress-relieved condition

81. Heat Treatment Process Flow

Raw Material Verification

↓

Forging

↓

Rough Machining

↓

Heat Treatment

↓

Straightening

↓

Final Machining

↓

Thread Formation

↓

Inspection

↓

Packaging

82. Manufacturing Workflow – Titanium Fasteners

Titanium fastener production requires tighter process controls than stainless steel or carbon steel fasteners.

SM Fasteners integrates manufacturing controls within its ISO 9001 quality management system to ensure consistency, traceability, and compliance with customer specifications.

83. Raw Material Verification

Every manufacturing cycle begins with material verification.

Verification includes:

• Heat number validation
• Chemical composition review
• Mechanical property review
• Material Test Certificate verification
• Positive Material Identification (PMI)

Applicable standards:

• ASTM B348
• ASTM B381

84. Material Test Certificate (MTC) Review

Incoming titanium material is verified against:

Requirement	Verification Method
Chemistry	Spectrometer Analysis
Mechanical Properties	MTC Review
Heat Number	Traceability Check
Dimensions	Incoming Inspection
Grade Verification	PMI Testing

85. Hot Forging Process

Forging improves:

• Grain flow
• Mechanical properties
• Structural integrity
• Fatigue resistance

Common forged products:

• Hex bolts
• Heavy hex bolts
• Custom fasteners

86. CNC Machining Operations

Precision machining produces:

• Tight tolerances
• Complex geometries
• Custom fasteners
• Aerospace-grade features

Operations include:

• Turning
• Milling
• Drilling
• Threading
• Slotting

87. Thread Rolling vs Thread Cutting

Critical Engineering Topic

Thread Rolling

Advantages:

• Compressed grain flow
• Increased fatigue resistance
• Better surface finish
• Improved thread strength

Thread Cutting

Advantages:

• Suitable for special threads
• Large diameters
• Custom configurations

Parameter	Rolled Thread	Cut Thread
Fatigue Strength	Higher	Lower
Surface Finish	Better	Moderate
Production Rate	Faster	Slower
Cost Efficiency	Better	Moderate

For critical industrial fasteners, rolled threads are generally preferred.

88. Surface Finish Requirements

Surface condition directly affects:

• Corrosion resistance
• Fatigue life
• Galling tendency
• Torque consistency

Common roughness requirements:

Surface	Typical Ra
General Industrial	3.2 µm
Precision Fasteners	1.6 µm
Aerospace Quality	<0.8 µm

89. Titanium Surface Finishing Methods

Finish Type	Purpose
Mechanical Polishing	Improved surface quality
Glass Bead Blasting	Uniform appearance
Pickling	Oxide removal
Passivation	Surface stabilization
Electropolishing	Enhanced cleanliness

90. Surface Finish Comparison Table

Finish	Corrosion Resistance	Appearance	Galling Reduction
As Machined	Good	Industrial	Moderate
Polished	Very Good	Smooth	Improved
Glass Bead Blasted	Good	Uniform Matte	Moderate
Passivated	Excellent	Clean Surface	Good
Electropolished	Excellent	Bright Finish	Excellent

91. Coating Considerations for Titanium Fasteners

Unlike carbon steel fasteners, titanium generally does not require protective coatings for corrosion resistance.

Coatings are primarily used for:

• Galling reduction
• Friction control
• Torque consistency
• Assembly improvement

92. Functional Coatings for Titanium Fasteners

Coating	Primary Benefit
PTFE	Low friction
MoS₂	Anti-galling
Dry Film Lubricant	Torque consistency
Xylan	Chemical resistance
Fluoropolymer Systems	Corrosion enhancement

93. Titanium vs Coated Carbon Steel Fasteners

Property	Titanium	HDG Carbon Steel
Weight	Very Low	High
Corrosion Resistance	Excellent	Moderate
Maintenance	Minimal	Periodic
Service Life	Long	Medium
Initial Cost	Higher	Lower
Lifecycle Cost	Often Lower	Higher

94. PEEK Fasteners vs Titanium Fasteners

SM Fasteners also manufactures advanced PEEK fasteners for specialized applications.

Property	Titanium	PEEK
Strength	Higher	Moderate
Weight	Low	Very Low
Electrical Conductivity	Conductive	Insulating
Chemical Resistance	Excellent	Excellent
Temperature Capability	Higher	Moderate
Non-Metallic Requirement	No	Yes

PEEK fasteners are selected where electrical insulation or metal-free construction is required.