BLU R1 HD is a great budget smartphone for those who don't want the latest and greatest camera or fastest processor. It's also a great smartphone for kids or as an extra backup phone in case your primary phone dies. It's even great for use with FreedomPop LTE GSM sims which give you 700mb free cellular data every month!
The first thing to do is check for new software updates for your phone. Updates fix bugs that cause overheating. If there are no updates, try doing a factory reset. If the problem continues, it's likely the software is causing the phone to overheat.
It's normal for your phone to heat up when charging it. The battery, the screen and the CPU work hard to transfer power in and out of the battery, which makes it hot. However, if the temperature of your phone gets too high, it will decrease the charging wattage to manage the heat.
Another common reason your BLU R1 HD may be overheating is because you have a case on it. Smartphones dissipate a lot of heat through the body, but a case increases this process and can prevent your phone from cooling down. If your BLU R1 HD is overheating, try removing the case while charging it. You can put the case back on once it finishes charging. Also, make sure you are charging your device in a cool environment.