15:14 the graph you make here weld metal temp. is aways greater than haz but in lecture 40 22:36 you explained transfer of hydrogen to haz as it has more temperature .
Baba , weld pool ka temp jyada hota h HAZ se no doubt , but cooling rate weld pool ka jyada h HAZ se..toh jitna der mein 1000 se 100 pahuchega weld pool utne der mein HAZ 900 se 800 hi pahuch pata h and at that particular moment HAZ k temp weld pool se jyada ho jata h !!! Chapo!!
High cooling rate in liquid produces fine structure because there will be only nucleation but no growth due to diffusion is restricted. But in the case of heat affected zone there will be no liquid forming, grains on exposure to high temperature there is increase in austenitic grain size, but high cooling rate in heat affected zone causes fine pearlite ( interlamellar spacing in pearlite is very less and strength increases where grain size is same of coarse austenitic grain formed). So you need to see the difference between the grain size and fine pearlite.
I liked it thank you very much good morning
15:14 the graph you make here weld metal temp. is aways greater than haz but in lecture 40 22:36 you explained transfer of hydrogen to haz as it has more temperature .
aha sobali sab padh liya tune :P
Baba , weld pool ka temp jyada hota h HAZ se no doubt , but cooling rate weld pool ka jyada h HAZ se..toh jitna der mein 1000 se 100 pahuchega weld pool utne der mein HAZ 900 se 800 hi pahuch pata h and at that particular moment HAZ k temp weld pool se jyada ho jata h !!! Chapo!!
High cooling rate produces fine grain then how can weld zone have coarse structure???
High cooling rate in liquid produces fine structure because there will be only nucleation but no growth due to diffusion is restricted. But in the case of heat affected zone there will be no liquid forming, grains on exposure to high temperature there is increase in austenitic grain size, but high cooling rate in heat affected zone causes fine pearlite ( interlamellar spacing in pearlite is very less and strength increases where grain size is same of coarse austenitic grain formed). So you need to see the difference between the grain size and fine pearlite.
Excellent