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  1. GonzaloMartinez

    Chevron marks in copper alloy?

    Thank you EdStainless, matengr, mrfailure! It is always enlightening to read your answers.
  2. GonzaloMartinez

    Chevron marks in copper alloy?

    Hello everyone, I have this fractured copper alloy shaft that shows what looks to me as chevron marks pointing to a single iniciation site. On SEM examination the mode of fracture observed was ductile overload. I have always associated chevron marks to brittle fracture. Is it possible to see...
  3. GonzaloMartinez

    Doubts on 4140 steel microstructure

    Hi sravii, chemistry was confirmed by optical emission spectroscopy; all elements of interest fall within the ranges for SAE 4140 (SAE J404). As to the material and heat treatment specification, I live in an area with lots of machine shops, few material specialist and poor steel suppliers. You...
  4. GonzaloMartinez

    Doubts on 4140 steel microstructure

    WKTaylor there wasn't any precise specification, the component was made with the material available at the shop. And well..... there are the results... Thank you all for your help! I think I got enough information to reduce my bibliographic search.
  5. GonzaloMartinez

    Doubts on 4140 steel microstructure

    Yes I have! Hardness measurement resulted in values around 24-25 HRC. The component under study fractured in a brittle way, probably under a shock load. We have done charpy-V tests resulting in very low values for the absorbed impact energy, aproximately 6 Joules at room temperature.
  6. GonzaloMartinez

    Doubts on 4140 steel microstructure

    Hello everyone, I would like to hear (read) your thoughts on the image I'm posting. It belongs to a 4140, 2" diameter steel bar . Notice the coarse acicular structure + fine pearlite grains (?). I was told by a material specialist that it corresponds to the absence of heat treatment after...
  7. GonzaloMartinez

    Need help identifying microstructure. SAE 1212?

    Thank you CoryPad for your help. I have search a bit better and I found that the lines sorrounding the black areas (pearlite)that were getting on my nerves might be "ghost structures" due to the phosphorus presence. Here is the source Link
  8. GonzaloMartinez

    Need help identifying microstructure. SAE 1212?

    Hello everyone, I'm currently dealing with a sample that belongs to a hydraulic quick coupling that had fracture after an external load was apllied due to a lateral pulling of the hose. CQ 0.19 C, 1.10 Mn, <0.0100 Si, 0.11 Cr, 0.195 Cu, 0.087 Ni, 0.028 Mo, [highlight #F57900]0.0965...
  9. GonzaloMartinez

    Verification of leeb hardness instrument

    Thank you for your answers. Finally we found the manufacturer's documentation of the test block and the issue was solved. I appreciate your concern. Regards, Gonzalo.
  10. GonzaloMartinez

    Verification of leeb hardness instrument

    Hello everyone, we are trying to do the verification of a portable hardness tester acording to ASTM A956 Part B. "Verification of leeb hardness instruments by a standarized block method". The criterion given in 15.1 and 15.2 states that the instrument shall be considered verified if two...
  11. GonzaloMartinez

    Damaged threads

    Here is a picture of the mating threaded hole. I looks in good shape to me. Could this damage corresponds to an overtorque of the joint?? The material is torn in the direction of friction force on tightening procedure (left handed thread). Something I haven't told you yet is that the joint...
  12. GonzaloMartinez

    Damaged threads

    Thank you, I appreciate your replies. RafaelCosta the material is medium carbon steel SAE 4140, quenched and tempered. The material was checked by chemical composition measurement and metallography. I would have expected higher hardness, the measurement gave 27 HRC. Regards.
  13. GonzaloMartinez

    Damaged threads

    Hello everyone, I want to know if someone can help me identify this mechanism of damage so I can look it up in the bibliography by its proper name. Thank you. (Reference in millimeters)
  14. GonzaloMartinez

    API 5L Gr. X70 as pressure vessel shell

    Thank you weldstan and jte for your help. Sorry jte, I was in a hurry and I missed that important piece of information... yes, I am working with ASME BPVC Section VIII, Division 1. You are rigth, the pressure vessel was fabricated few years ago, it doesn't have any ASME stamp. The actual owner...
  15. GonzaloMartinez

    API 5L Gr. X70 as pressure vessel shell

    Hello everyone, I know that this issue has been discussed before but I need further help please. The thing is that it came to me a 36" diameter pressure vessel whose shell is made of a API 5L Gr. X70 welded pipe. I want to know if this material can be recertified as a material accepted by the...
  16. GonzaloMartinez

    Old boiler material

    Sorry, I couldn´t find the words to explain it, maybe with a picture. The red arrow indicates this "ring" that I´m refering to, and yes, it has refractory in the same disposition as the picture. What you are suggesting makes sense to me.
  17. GonzaloMartinez

    Old boiler material

    Thank you for your answers. Mentengr, I thought it could be something related to material provision because the rest of the material from the corrugated furnace (next replica taken 5" far from this ring, welded joint in between) shows ferrite-pearlite microstructure without degradation. I found...
  18. GonzaloMartinez

    Old boiler material

    Hello everyone, During a inspection by replica technique in a 40 year old boiler, we got to these micrographs. The first one belongs to the corrugated furnace (seems like no microstructural degradation) and the second to a ring located in the mouth of the furnace. The client provided us a...
  19. GonzaloMartinez

    steel structure afected by fire

    Hello Tito54, maybe you can take metallographic replicas on the affected elements. Through this non destructive technique an expert should be able to evaluate if the microstructure of the steel used has been affected by the fire and therefore its mechanical properties. Hardness can give you...
  20. GonzaloMartinez

    SAE 1144 shaft fracture surface morphology

    I promised that I was going to post some micrographs so... after having some trouble (I'm taking my first steps on metallography) here they are: Longitudinal and transversal samples, notice the amount of inclusions. It looks to me like ferrite and pearlite, I was expecting to find martensite...

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