cement post inside metal post

[soups05]

Hi guys,odd sort of question for you. I have a set of metal gates which a local dipstick hit with his daddys car.(16 years old and out for a joyride) after waiting months for an apology and getting nothing i decided that i would need to fix it myself.
I purchased a welder, cheap adli job but all i could afford, and after a lot of practise i done what i think is a pretty fair job at welding.
when we lifted the gate back on,allowing a couple of hours for the welds to cool and set while i had a lunch break and done some other little jobs, the post cracked at the weld straight away.
I have reached the limit of my welding abilties so have come up with another apporach. and need some advice.
at the moment i have rewelded the post. it seems secure but will not bear the weight of the heavy gate. so i am thinking i can cut the top off of the post,insert a 12 inch long bolt to act as rebar,and fill the post with cement.

would this have the effect of strenghting the post or will it be a waste of time. i have never worked with cement so don't know what sort of mix or quantity i would need for a post about 3 inches wide by about 3.5 foot tall.
suggestions would be helpful.

 

[wotan]

I think you need to re-examine your welding techniques, gouge the weld out again with an angle grinder to a 'V' shape then build up the weld in several layers, knock the slag off after each pass.
An Aldi welder might not be up to the job though, it will have a very short duty cycle at the amps you need, but it may be possible with some perseverance, good luck.

Wotan

 

[Alarm]

As said gouge out and reweld, cleaning out the slag after each pass.
Also buy some 3mm plate and weld to the post over the joint, this will strengthen your weld.

Or ask a local smitthy to run a weld for you.