Task: Sentence Expansion
Input (English): Though the process of peening has become rarer in metal fabrication , the ball-peen hammer remains useful for many tasks , such as striking punches and chisels .
Output (English): Though the process of peening ( surface hardening by impact ) has become rarer in metal fabrication , the ball-peen hammer remains useful for many tasks , such as striking punches and chisels ( usually performed with the flat face of the hammer ) .