百炼成刚

Explanation: Just through steel. Iron after repeated tempering steel will become tough. After repeated analogy of people to become useful before honing. 　　Source: Guo Xiaochuan "defend our party's" Poetry lit the flames of struggle, a hundred people in the fire Make Gang. " 　　Examples: Some veteran, ~, reached a pinnacle, hi in the heart without form or color. ★ Xu Chi "fire phoenix phoenix"