Free-cutting copper alloy casting, and method for producing free-cutting copper alloy casting

Abstract

This copper alloy casting includes, in terms of mass %: Cu: higher than 58.5% and lower than 65.0%; Si: higher than 0.40% and lower than 1.40%; Pb: higher than 0.002% and lower than 0.25%; P: higher than 0.003% and lower than 0.19%; and Bi: 0.001% to 0.100% as an optional element, with the balance being Zn and inevitable impurities, the total content of Fe, Mn, Co, and Cr is lower than 0.45% and the total content of Sn and Al is lower than 0.45%, a relationship of 56.0≤f1=[Cu]−5×[Si]+0.5×[Pb]+0.5×[Bi]−0.5×[P]≤59.5 is satisfied, when Bi is included, a relationship of 0.003<f0=[Pb]+[Bi]<0.25 is further satisfied.

1 . A free-cutting copper alloy casting comprising:
 higher than 58.5 mass % and lower than 65.0 mass % of Cu;   higher than 0.40 mass % and lower than 1.40 mass % of Si;   higher than 0.002 mass % and lower than 0.25 mass % of Pb;   higher than 0.003 mass % and lower than 0.19 mass % of P; and   higher than or equal to 0.001 mass % and lower than or equal to 0.100 mass % of Bi as an optional element,   with the balance being Zn and inevitable impurities,   wherein among the inevitable impurities, the total content of Fe, Mn, Co, and Cr is lower than 0.45 mass % and the total content of Sn and Al is lower than 0.45 mass %,   when a Cu content is represented by [Cu] mass %, a Si content is represented by [Si] mass %, a Pb content is represented by [Pb] mass %, a Bi content is represented by [Bi] mass %, and a P content is represented by [P] mass %, a relationship of
   56.0 ≤f 1=[Cu]−5×[Si]+0.5×[Pb]+0.5×[Bi]−0.5×[P]≤59.5 is satisfied,
 
   when Bi is not included, [Bi] in f1 is 0,   when Bi is included, a relationship of
   0.003 <f 0=[Pb]+[Bi]<0.25 
   is further satisfied,   in constituent phases of a metallographic structure excluding non-metallic inclusions, when an area ratio of α phase is represented by (α)%, an area ratio of γ phase is represented by (γ)%, and an area ratio of β phase is represented by (β)%, relationships of
   20≤(α)≤80,
 
   18≤(β)≤80,
 
   0≤(γ)<5,
 
   20×(γ)/(β)<4,
 
   18≤(γ) 1/2 ×3+(β)×(−0.5×[Si] 2 +1.5×[Si])≤82, and
 
   33≤(γ) 1/2 ×3+(β)×(−0.5×[Si] 2 +1.5×[Si])+([Pb]+[Bi]) 1/2 ×38+([P]) 1/2 ×15
 
   are satisfied,   when Bi is not included, [Bi] in the expression is 0, and   a compound including P is present in β phase.   
     
     
         2 . A free-cutting copper alloy casting comprising:
 higher than 59.0 mass % and lower than 65.0 mass % of Cu;   higher than 0.50 mass % and lower than 1.35 mass % of Si;   higher than 0.010 mass % and lower than 0.20 mass % of Pb;   higher than 0.010 mass % and lower than 0.15 mass % of P; and   higher than or equal to 0.001 mass % and lower than or equal to 0.100 mass % of Bi as an optional element,   with the balance being Zn and inevitable impurities,   wherein among the inevitable impurities, the total content of Fe, Mn, Co, and Cr is lower than 0.40 mass % and the total content of Sn and Al is lower than 0.40 mass %,   when a Cu content is represented by [Cu] mass %, a Si content is represented by [Si] mass %, a Pb content is represented by [Pb] mass %, a Bi content is represented by [Bi] mass %, and a P content is represented by [P] mass %, a relationship of
   56.0 ≤f 1=[Cu]−5×[Si]+0.5×[Pb]+0.5×[Bi]−0.5×[P]≤59.5
 
   is satisfied,   when Bi is not included, [Bi] in f1 is 0,   when Bi is included, a relationship of
   0.020 ≤f 0=[Pb]+[Bi]<0.20 
   is further satisfied,   in constituent phases of a metallographic structure excluding non-metallic inclusions, when an area ratio of α phase is represented by (α)%, an area ratio of γ phase is represented by (γ)%, and an area ratio of β phase is represented by (β) %, relationships of
   25≤(α)≤75,
 
   25≤(β)≤75,
 
   0≤(γ)<3,
 
   20×(γ)/(β)<2,
 
   25≤(γ) 1/2 ×3+(β)×(−0.5×[Si] 2 +1.5×[Si])≤76, and
 
   40≤(γ) 1/2 ×3+(β)×(−0.5×[Si] 2 +1.5×[Si])+([Pb]+[Bi]) 1/2 ×38+([P]) 1/2 ×15
 
   are satisfied,   when Bi is not included, [Bi] in the expression is 0, and   a compound including P is present in β phase.   
     
     
         3 . A free-cutting copper alloy casting comprising:
 higher than 59.5 mass % and lower than 64.5 mass % of Cu;   higher than 0.60 mass % and lower than 1.30 mass % of Si;   higher than 0.010 mass % and lower than 0.15 mass % of Pb;   higher than 0.020 mass % and lower than 0.14 mass % of P; and   higher than 0.020 mass % and lower than or equal to 0.100 mass % of Bi, with the balance being Zn and inevitable impurities,   wherein among the inevitable impurities, the total content of Fe, Mn, Co, and Cr is lower than 0.35 mass % and the total content of Sn and Al is lower than 0.35 mass %,   when a Cu content is represented by [Cu] mass %, a Si content is represented by [Si] mass %, a Pb content is represented by [Pb] mass %, a Bi content is represented by [Bi] mass %, and a P content is represented by [P] mass %, relationships of
   0.040 <f 0=[Pb]+[Bi]<0.18 and 
   56.5 <f 1=[Cu]−5×[Si]+0.5×[Pb]+0.5×[Bi]−0.5×[P]≤59.0
 
   are satisfied,   in constituent phases of a metallographic structure excluding non-metallic inclusions, when an area ratio of α phase is represented by (α)%, an area ratio of γ phase is represented by (γ)%, and an area ratio of β phase is represented by (β)%, relationships of
   30≤(α)≤70,
 
   30≤(β)≤70,
 
   0≤(γ)<2,
 
   20×(γ)/(β)<1,
 
   30≤(γ) 1/2 ×3+(β)×(−0.5×[Si] 2 +1.5×[Si])≤70, and
 
   45≤(γ) 1/2 ×3+(β)×(−0.5×[Si] 2 +1.5×[Si])+([Pb]+[Bi]) 1/2 ×38+([P]) 1/2 ×15
 
   are satisfied,   a compound including P is present in β phase, and a particle including Bi is present in α phase.   
     
     
         4 . The free-cutting copper alloy casting according to  claim 1 ,
 wherein a solidification temperature range is 25° C. or lower.   
     
     
         5 . The free-cutting copper alloy casting according to  claim 1 ,
 wherein a Vickers hardness is 105 Hv or higher, and   an impact value obtained when a U-notch impact test is performed is 25 J/cm 2  or higher.   
     
     
         6 . The free-cutting copper alloy casting according to  claim 1 , which is used for a mechanical component, an automobile component, an electrical or electronic apparatus component, a toy, a sliding component, a pressure vessel, a measuring instrument component, a precision mechanical component, a medical component, a fitting for construction, a faucet fitting, a drink-related device or component, a device or component for water drainage, or an industrial plumbing component. 
     
     
         7 . A method for producing the free-cutting copper alloy casting according to  claim 1 , the method comprising:
 a melting and casting step,   wherein in the melting and casting step, an average cooling rate in a temperature range from 530° C. to 450° C. in a process of cooling after casting is in a range of 0.1° C./min or higher and 55° C./min or lower.   
     
     
         8 . The free-cutting copper alloy casting according to  claim 2 ,
 wherein a solidification temperature range is 25° C. or lower.   
     
     
         9 . The free-cutting copper alloy casting according to  claim 3 ,
 wherein a solidification temperature range is 25° C. or lower.   
     
     
         10 . The free-cutting copper alloy casting according to  claim 2 ,
 wherein a Vickers hardness is 105 Hv or higher, and   an impact value obtained when a U-notch impact test is performed is 25 J/cm 2  or higher.   
     
     
         11 . The free-cutting copper alloy casting according to  claim 3 ,
 wherein a Vickers hardness is 105 Hv or higher, and   an impact value obtained when a U-notch impact test is performed is 25 J/cm 2  or higher.   
     
     
         12 . The free-cutting copper alloy casting according to  claim 4 ,
 wherein a Vickers hardness is 105 Hv or higher, and   an impact value obtained when a U-notch impact test is performed is 25 J/cm 2  or higher.   
     
     
         13 . The free-cutting copper alloy casting according to  claim 2 , which is used for a mechanical component, an automobile component, an electrical or electronic apparatus component, a toy, a sliding component, a pressure vessel, a measuring instrument component, a precision mechanical component, a medical component, a fitting for construction, a faucet fitting, a drink-related device or component, a device or component for water drainage, or an industrial plumbing component. 
     
     
         14 . The free-cutting copper alloy casting according to  claim 3 , which is used for a mechanical component, an automobile component, an electrical or electronic apparatus component, a toy, a sliding component, a pressure vessel, a measuring instrument component, a precision mechanical component, a medical component, a fitting for construction, a faucet fitting, a drink-related device or component, a device or component for water drainage, or an industrial plumbing component. 
     
     
         15 . The free-cutting copper alloy casting according to  claim 4 , which is used for a mechanical component, an automobile component, an electrical or electronic apparatus component, a toy, a sliding component, a pressure vessel, a measuring instrument component, a precision mechanical component, a medical component, a fitting for construction, a faucet fitting, a drink-related device or component, a device or component for water drainage, or an industrial plumbing component. 
     
     
         16 . The free-cutting copper alloy casting according to  claim 5 , which is used for a mechanical component, an automobile component, an electrical or electronic apparatus component, a toy, a sliding component, a pressure vessel, a measuring instrument component, a precision mechanical component, a medical component, a fitting for construction, a faucet fitting, a drink-related device or component, a device or component for water drainage, or an industrial plumbing component. 
     
     
         17 . A method for producing the free-cutting copper alloy casting according to  claim 2 , the method comprising:
 a melting and casting step,   wherein in the melting and casting step, an average cooling rate in a temperature range from 530° C. to 450° C. in a process of cooling after casting is in a range of 0.1° C./min or higher and 55° C./min or lower.   
     
     
         18 . A method for producing the free-cutting copper alloy casting according to  claim 3 , the method comprising:
 a melting and casting step,   wherein in the melting and casting step, an average cooling rate in a temperature range from 530° C. to 450° C. in a process of cooling after casting is in a range of 0.1° C./min or higher and 55° C./min or lower.   
     
     
         19 . A method for producing the free-cutting copper alloy casting according to  claim 4 , the method comprising:
 a melting and casting step,   wherein in the melting and casting step, an average cooling rate in a temperature range from 530° C. to 450° C. in a process of cooling after casting is in a range of 0.1° C./min or higher and 55° C./min or lower.   
     
     
         20 . A method for producing the free-cutting copper alloy casting according to  claim 5 , the method comprising:
 a melting and casting step,   wherein in the melting and casting step, an average cooling rate in a temperature range from 530° C. to 450° C. in a process of cooling after casting is in a range of 0.1° C./min or higher and 55° C./min or lower.