1.PROBLEMS 3.11

 

 
1.An AISI 4340 steel part is annealed to 217 Bhn.Estimate the valued of Su and Sy Compare these values with those corresponding to another AISI 4340 steel part that is normalized to 363 Bhn.

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Known :
An AISI 4340 steel part is annealed to 217 Bhnanother
  AISI 4340 steel part is normalized to 363 Bhn
 
Find :
   Estimate the values of Su and Sy
     
Assumption :
   1. The experimentally determined relationship of ultimate strength to hardness is sufficiently accurate.
    2. The experimentally developed relationship of yield strength ultimate strength is sufficiently accurate for our purposes.
    For most steels ,KB=500
     
       
Analysis :
   Su 1... AISI 4340,217 Bhn
            Su = KB HB
           
Su = 500 (217) = 108500 psi Ans.
             
            Su 2... AISI 4340,363 Bhn
            Su = KB HB
            Su = 500 (363) = 181500 psi Ans.
             
            Where KB = 500 to most steels:
             
            Sy 1... AISI 4340,217 Bhn
            Sy = 1.05 Su -30,000
            Sy = 1.05 (108500) – 30,000= 83925 psi Ans.
             

 

           Sy 2... AISI 4340,363 Bhn
            Sy = 1.05 Su – 30,000
            Sy = 1.05 (181500) – 30,000= 160575 psi Ans.
             
       
Comments :
   Experimentel data would be helpful in refining the preceding equations for this materrial.
             
             
 

I:AISI ,Number
Tensile Strength
Yield Strehgth
Elongation
Reduction in Area
Brinell Hardness
Izod Impact Strength
Treatment
MPa
ksi
MPa
ksi
(%)
(%)
HB
J
ft.lb
4340
Normalized
1279.0
185.5
861.8
125.0
12.2
36.3
363
15.9
11.7
Annealed
774.6
108.0
472.3
68.5
22.0
49.9
217
51.1
37.7