Patent ID: 11946856
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 4:
5. A steel fracture starting point estimation device that estimates a fracture starting point of steel, the steel fracture starting point estimation device comprising:
a hydrogen concentration distribution calculation unit adapted to calculate a hydrogen concentration distribution in steel-to-be-estimated when the steel fractures due to hydrogen embrittlement;
a local critical hydrogen content calculation unit adapted to calculate critical hydrogen content at which the steel-to-be-estimated fractures due to hydrogen embrittlement; and
a fracture starting point estimation unit adapted to read the hydrogen concentration distribution out of a storage unit, calculate, from the hydrogen concentration distribution, a location in the steel in which hydrogen concentration of the critical hydrogen content is distributed, and designate the location in the steel as the fracture starting point of the steel-to-be-estimated;
wherein the hydrogen concentration distribution calculation unit calculates a hydrogen diffusion coefficient of the steel-to-be-estimated based on variation of hydrogen content in the steel with time on assumption that hydrogen diffuses in the steel, and calculates the hydrogen concentration distribution based on the following diffusion equation:, C
      
       C
       s
      
     
     =
     
      
       4
       a
      
      ⁢
      
       
        (
        
         
          D
          ⁢
          t
         
         π
        
        )
       
       
        1
        2
       
      
     
    
   
   
    
     (
     1
     )
    
   
  
 

where C is a hydrogen content in the steel-to-be-estimated, Cs is a saturated hydrogen content, α is a radius of the steel-to-be-estimated, D is the hydrogen diffusion coefficient, and t is a hydrogen charging time.