【導(dǎo)讀】1.20鋼的介紹·······················1. 20鋼的化學(xué)成分與基本力學(xué)性能···············2. .20鋼的焊接性·······················2. 焊接時(shí)存在的問題·····················3. 2焊接方法的選擇························4