Can you anneal PLA and or PETG?

I was wondering if you can strengthen a 3d print in a convection oven if so what temp and for how long and does it actually make the print stronger or something?

Here is an article I found just about this topic

Basically yes It does strengthen your plastic prints, why/how is basically because it remelts a portion of the plastic and increases the bonding between the layers. You can do it a number of ways, most common is with a toaster oven (convection) or hot water. Granted the hot water method is not quite as predictable .

Joel also has a really good video about it

The article actually has some really good explanations about it.
Hope this helps

As I recall, CNC Kitchen did some strength testing on annealed vs. non-annealed prints. He’s done a few of them. Google “cnckitchen anneal”