Junk bonds are all the rage these days, as investors search for high returns on investments amid stock market woes and low interest rates. So is now the time to buy? Maybe, if you can stomach the risk. A total of $30 billion worth of high-yield corporate bonds, or junk bonds, were issued in the first four months of this year alone, compared with last year's full-year total of $59 billion, according to Thomson First Call. But with the high returns come dangers: If the economy doesn't improve and companies continue to struggle, they may be likely to default. "Investors willing to take the risk in high yield now are assuming a large improvement in the economy and lower default rates. But some of these companies ... still face underpinnings related to pension funding, pricing power," said Diane Keefe, portfolio manager at Pax World High-Yield Fund. Nonetheless, in March, junk-bond junkies were on a roll, with almost 70% of all flows into bond funds going into high-yield securities, according to research firm AMG Data Services. Junk bonds, which became prominent in the '80s, offer much higher interest payments than other types of bonds, because they carry low credit ratings. Companies issue junk as a convenient way to tap the corporate bond market and raise some money. Some high-yield experts, such as Tom Huggins, portfolio manager at Eaton Vance, expect strong returns from junk bonds this year, predicting that mutual funds specializing in them will reap yields of 30% to 40% on average. So far this year, returns on high-yield funds are hovering around 10%, according to Morningstar. Keefe at Pax World notes that default rates recently have dwindled, but if the economy continues to stagnate, defaults could start to pop up again. According to Fitch Ratings, the rate of defaults among high-yield issuers in the first quarter this year fell to $6.5 billion, or 1.1% of all the volume of bonds outstanding, from $26.3 billion, or 5%, in the same period a year earlier.