What method is used to eliminate crater cracks in aluminum alloys?

What method is used to eliminate crater cracks in aluminum alloys?
 
  A) Backstepping
  B) Craterfill
  C) Adding filler metal
  D) Trigerring
  E) All of the above

 Q. 2

What is the net stack temperature?
 
  A) The sum of the stack temperature and the ambient temperature
  B) The temperature difference between the over fire temperature and the stack temperature
  C) The temperature difference between the over fire temperature and the ambient temperature
  D) The temperature difference between the stack temperature and the ambient temperature

 Q. 3

Preheating of the weldment helps to:
 
  A) Remove moisture B) Reduce martensite formation
  C) Reduce hydrogen absorption D) All of the above