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  • Users: Naruwan
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  1. Naruwan

    How detrimental is secondary austenite in Duplex Stainless Steel?

    Hi, I had been performing lots of ferrite count (in accordance to ASTM E562)on super/ duplex stainless steels. Besides ferrite count, we also had been performing ASTM G48 Method A pitting corrosion test on these stainless steels. Some specimens did failed the corrosion test. They normally...
  2. Naruwan

    Sigma stringers or delta ferrite stringers?

    Hi guys, I have a problem identifying the 'foreign' structure in this 316L heat affected zone. Attached is a photo-micrograph of a SS316L HAZ at 500X. I had used 10% Oxalic acid to etch the structure and found out there's strange structures which looked either like sigma phase or delta...
  3. Naruwan

    Ways to differentiate type of rust

    Hi guys, is there any way to determine the difference between Fe2+ and Fe3+? I don't think telling the difference by the colour of the rust will be reliable enough. In addition, had anyone heard of black rust from steel? They should be iron oxide which had been oxidized in a high temperature...
  4. Naruwan

    Component failed by fatigue?

    Hi Guys! one of our neighouring company passed this component to us and we are figuring what caused the failure. I reckon it was caused by fatigue, but not sure. This component seemed to have a flange like piece connect to a shaft. That's where it failed. It seemed that there are concentric...
  5. Naruwan

    Killed steel's grain size

    Dear all, I know that killed steel will need a content of Aluminum and Silicon as they are strong deoxidizers. a) Is there a different range (for these elements)for different grades of steel? b) Aluminum as a deoxidizer and for the control of grain size, then, how fine must the grain size be...
  6. Naruwan

    Questions regarding ASTM A90/ A 90M

    Hi guys, according to ASTM A90/ A 90M, nothing was mentioned about the removal of a paint coating before performing the stripping test as to determine the mass of coating on Iron or steel plates with metallic coating. Is paint removal a good media to remove the paint without jeopardizing the...
  7. Naruwan

    Shaft failed by torsion?

    Hi guys, I just got this one and only photo from my client regarding a broken shaft. Based on this picture, I reckon it was failed by torsion. Of course I will be accessing this shaft tomorrow and hopefully will be getting more photos. Any comments? Thanks!
  8. Naruwan

    What structure is this?

    Dear all, i had etched a piece of annealed stainless steel 440C material with 10% Oxalic acid, however I can't identify any traces of martensitic structure. In addition, are the white islands carbide? I had attached a photomicrograph taken at 500X for viewing. Thanks!
  9. Naruwan

    Is this failure by shear or fatigue?

    Dear all, I had just received a photo of the failed shaft's fractured surface and I was wondering if this fracture surface is caused by shear or fatigue. I had asked our mentor regarding this and he claimed that it was caused by fatigue due to the fact that there were ratchet marks at the left...
  10. Naruwan

    Etching copper and aluminium

    Dear all, I have an electrical component which is made up of copper at one side and aluminium on the other. They are fused together by friction welding. Is there any etchant that will etch both of these two material at one time? Or do I need to etch one material at one time?
  11. Naruwan

    Can I determine this microstructure grain size?

    Dear all, I have a steel bend pipe, material: ISO 3183-3. The location for microstructure and grain size determination (according to E112) was taken at the mid bend inner of the pipe. From the picture attached, it seemed to be tempered martensite with disperse ferrite. If this is the case, do...
  12. Naruwan

    Is this tempered martensite?

    Dear all, can anyone advise me is the microstructure in the picture that I had attached tempered martensite? Thanks!
  13. Naruwan

    Stainless steel slip bands?

    Hi, I had read that slip bands in the grains of stainless steel's microstructure is a sign of cold working. Like to have some advice on the photo-micrograph I had attached. Are these slip bands? Will solution annealing remove slip bands? Cheers!
  14. Naruwan

    Problem with SS304L flange

    Hi, our client had a problem in his solution annealing problem with his 304L flange. Size: 6inch diameter with 0.8inch thickness and 300 pound force. He stated that he heat treated his flange at 1050 degree celsius and held at that temperature for an hour. However, looking at the cross...
  15. Naruwan

    Specimen preparation in accordance to ASTM G48 Method A

    Dear All, according to ASTM G48 Method A (Pitting corrosion test), we are suppose to polish all surfaces of the specimen to a uniform finish until a minimum of A120-grit. Does this applies to test specimens which have welding? Do we have to polish the weldment or leave it as it is. If yes...
  16. Naruwan

    Determining grain size for Tempered Martensite

    Dear all, I am having problem determining the grain size for AISI 4130 since it's microstructure will be of tempered martensite. I read it from ASTM E112 that I had to heat it up to 857 degree celsius, hold it there for an hour and quench it in water. Is anyone able to tell me what it is all...
  17. Naruwan

    ASTM G48 Method A test specimen preparation

    Dear All, according to ASTM G48 Method A (Pitting corrosion test), we are suppose to polish all surfaces of the specimen to a uniform finish until a minimum of A120-grit. Does this applies to test specimens which have welding? If yes, then are we not testing the original surface condition of...

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