air or water i do not see no need to use it anyway .it will normalize better just letting it cool down by it self. cooling will build in stress in the part and make it pull the best way is to tack them to steel I beam or tub or table so they will not move weld them and reheat them and let them cool down by them self. this is why i like a tig .but the mig will do the job and is faster but sometimes parts will pull more mig welded. that is why i woud go over the part with heat and let it cool down slow and it will be normalizes