7720 HARDESON RD BASE FILE 2016-01-01 MF Import

'" ��lahan _ Cz-;y of Everett Bldg. Dept. P�e 2 `'6� `-'•a- area through th grain structure and trapped adjacent to ��`- �'_: aifected zone, as salidification takes place. This con- �=�'-�a r.akes the steel in the heat affected zone more brittle �d =0�z 2=�°ptable to cracking. Also, the grain size in this area is �• ^' a-^ger and distributed unevenly. Carbon now lies in the grain ��:.^.dries in the form of pearlite, which is not very ductal and '��itn this condition and the risidual stresses, underbead cracking cecor.,es a likel,y possibility, after the weldment has been placed :n service. ' Vrhen :he proper preheat and interpass temperatures are maintained the carbon is allowed to move evenly out of the weld area and as the weld cools slowly, due to the fact that it was preiteated, the carbon is allowed to return slowly to the heat affected zone. The carbon is now redistributed evenly throughout the heat affected zone. This eliminates the quenching effect that results when the material is not preheated before welding due to the carbon being able to move evenly titrough the grain boundries. The grain struct- ure remains smaller, therefore the grain boundries are smaller and the carbon is distributed evenly throughout the smaller heat nf- fected zone. I have tried to explain this as :;imply as possible and I hope that you have been able to understand what I have said. If not, I can refer you to several reference books that will substazitiate my statements. Thank you for considering A& R, Inc., as a weld evaluating source and I hope that I have been of some help to you in this matter. If you have any further questions, please feel free to contact me Sincerely�; � / �� Steven V�. McNeven PJ.E. President SYIM/ J Z Enclosu:es cc: City of Everett Bldg. Dept. - VJally Christopherson W.A.D•0. - Lester Gillis Craig Eshleman Ted Smith �- J � �