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Recent content by safaeng

  1. safaeng

    what is this structure

    thanks,I have seen that before. I don't know the cooling rates at different regions to use the CCT diagram. all I know is that the cooling rate at the center of the fusion zone is about 3000K/S. This would be great if you could see the pictures of my second post here and make some comments on...
  2. safaeng

    what is this structure

    Thank you very much dear metengr! We had discussions about this, before :) So, please kindly, would you teach me how you differ between bainite and martensite there? ================================================ as we discussed earlier, I did a modified weld schedule on this material. new...
  3. safaeng

    what is this structure

    hi This is a resistance spot weld of steel (2 mm thickness) process: squeez-->weld(KA,Cycles)-->hold(40 cycles) material: C Mn Si P S Cr 0.15 1.02 0.17 0.012 0.011 0.004 Ni Mo Al Co V Ti Cu 0.02 0.009 0.037 0.002 0.003 0.001 0.03 In general the resistance weld structure consists of...
  4. safaeng

    metalography question

    metengr Here is What you said:) this is the one weld micro-hardness: and this one is a re-weld: actually it is a weld and temper schedule of weld squeez-->weld1-->cooling by copper electrode--->weld2(50%)-->hold-->release as you see we have a tempered region just before the HAZ. But...
  5. safaeng

    metalography question

    Well said metengr :) I am far from an expert in this. but indeed I can not see any reason to have tempered martensite there, neither. I couldn't find any CCT or TTT diagram of this steel because it is a Japanese grade steel JIS SAPH 440. Hence as I don't know the temperature history at...
  6. safaeng

    metalography question

    brimstoner; thanks for your answer. So you say that the WM (weld metal) structure is bainite and lath ferrite? If so, Let me notice the process, the metal is heated to well above AC3 (austenite) temprature and is cooled at about 5000 'C per second. As I know forming of bainitic structure...
  7. safaeng

    metalography question

    this is the micro-hardness profile of the weld. the line is the trace of micro-hardness measurement. and this is the best pic that I have got. I know the resolution is low :( but this is all I have got. and this is the weld metal structure:
  8. safaeng

    metalography question

    I am answering ........
  9. safaeng

    metalography question

    Hello I am looking for some help on this picture (attached) Ii is a resistance spot welded metal. Actually this picture is taken from the HAZ near to Weld metal. The base metal structure is ferrite and pearlite and the chemical composition is : C 0.15 Mn 1.02 Si 0.2 P, S, Al, Co, ~ 0.006 Mo...
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