If your loans are federal loans (from the US) you do not want to default on your loans. As someone else mentioned, you can get a deferment if your loan is a federal loan, after deferment, you then can get do a forbearance. I also believe there is one more extension you can get. So upfront you can get a two year extension.
If you default on a federal loan.. you will ruin your credit. If you ever plan to work in the US again, any money you get from tax returns will be claimed by the federal govt until the loan is paid off. High possibility of your wages being garnished,
The federal government may withhold part of your Social Security benefit payments. (The US Supreme Court upheld the government's ability to collect defaulted student loans in this manner without a statute of limitations in Lockhart v US (04-881, December 2005).)
Your defaulted loans will appear on your credit history for up to 7 years after the default claim is paid, making it difficult for you to obtain an auto loan, mortgage, or even credit cards. A bad credit record can also harm your ability to find a job. The US Department of Education reports defaulted loans to TransUnion, Equifax and Experian.
You'll be ineligible for deferments and Subsidized interest benefits will be denied.
It is very easy to get a deferment or a forbearance. Please consider this before defaulting on your student loan/s