Analysis of the Causes of Titanium Alloy Screw Failure and Usage Precautions

Titanium alloy screws are widely used in aerospace, precision machinery and other fields because of their “low density and high specific strength” characteristics. However, in actual use, titanium alloy screws may break due to a variety of factors. This paper objectively analyzes the common causes of titanium alloy screw fracture from the perspective of material properties, usage methods and maintenance, and puts forward targeted suggestions.

1. Material Properties And Strength Performance Of Titanium Alloy Screws

1) Specific Strength Advantage

① The “specific strength” (the ratio of strength to density) of titanium alloy is higher than that of steel, but the absolute strength is not outstanding. Its original design intention is to take into account lightweight and structural strength, and it is suitable for scenes that are sensitive to weight and need to be carried (such as aircraft structural parts).

② Comparative data: The tensile strength of titanium alloy screws is comparable to that of steel screws (usually 800-1200 MPa), but the density is only 60% of steel and the weight is lighter.

2) Source Of Fracture Risk

The fracture of titanium alloy is not due to insufficient material strength, but is closely related to the use environment, installation methods and maintenance conditions.

2. Common Causes Of Fracture Of Titanium Alloy Screws

1) Improper Installation Method

Insufficient torque control: Titanium alloy has a low elastic modulus (about half that of steel), and it is easy to cause plastic deformation or stress concentration due to excessive tightening when tightening, causing fracture. Thread bite problem: Failure to use a matching thread lubricant or insufficient thread accuracy may cause excessive local stress.

2) Environmental Impact Of Use

① Temperature Change: Titanium alloys may decrease in strength and toughness at high temperature (>400℃) or low temperature (<-100℃), increasing the risk of fracture.

② Corrosive Media: Long-term exposure to strong acids, alkalis, or environments containing chloride ions may cause hydrogen embrittlement or stress corrosion cracking.

3) Material Defects and Fatigue Damage

① Internal Defects: Titanium alloys may produce defects such as pores and inclusions during smelting or processing, which reduces fatigue life.

② Dynamic Load: When subjected to alternating loads (such as vibration and shock) for a long time, titanium alloy screws are prone to fatigue fracture.

4) Design And Selection Errors

① Mismatched Specifications: screws with insufficient diameter or length are selected, resulting in insufficient carrying capacity.

② Alternative Use: Using titanium alloy screws in non-design working conditions (such as ultra-high-strength demand scenarios) may cause fracture.

3. Measures To Prevent Titanium Alloy Screws From Breaking

1) Standardize Installation Operations

① Torque Control: Tighten strictly according to the torque value recommended by the manufacturer to avoid over-tightening or under-tightening.

② Thread Lubrication: Use special thread lubricants to reduce friction and stress concentration.

2) Optimize The Use Environment

① Temperature Management: Avoid long-term operation of titanium alloy screws at extreme temperatures, and adopt heat insulation or cooling measures if necessary.

② Corrosion Protection: Surface treatment (such as coating and coating) of screws that come into contact with corrosive media.

3) Regular Maintenance And Testing

① Fatigue Inspection: Regular non-destructive testing (such as ultrasonic flaw detection) of screws that withstand dynamic loads.

② Replacement Cycle: Formulate a reasonable replacement plan according to the working conditions of use to avoid overdue service.

4) Reasonable Selection And Design

① Matching Working Conditions: According to the actual load, temperature and medium conditions, select the appropriate titanium alloy grade (such as TC4, TC6).

② Redundant Design: double screws or reinforced structures are used in key parts to reduce the risk of fracture.

The fracture of titanium alloy screws is not simply caused by insufficient material strength, but is closely related to the installation method, use environment, material defects and design selection. Through standardized operation, optimized environment, regular maintenance and reasonable selection, the risk of fracture can be significantly reduced and the service life of titanium alloy screws can be extended.