iPhone 4 able to get replaced?

you will need applecare warranty then you will get a new iphone 4 thanks

If your based in the UK, all electrical equipment is covered by a mandatory one year warranty. I am not sure about the USA but I think there is something similar. Hope I am of help.

AppleCare is nothing more than a 1-2 year extension to the 1 year warranty (giving a total of 2-3 years depending on the product). If the iPhone is defective or some other similar issue occur, such as the battery going dead on you, Apple will replace it for free of charge under the 1 year warranty. With the 1 year warranty, you also get 90 days of telephone support, with AppleCare, this is extended till the warranty expires.

From Apple's site:

Every iPhone comes with one year of hardware repair coverage through its limited warranty and up to 90 days of complimentary support.1 The AppleCare Protection Plan for iPhone extends your coverage to two years from the original purchase date of your iPhone. Whether you use your iPhone with a Mac or a PC, just one phone call can help resolve most issues.