【摘要】 采用CO2气体保护焊,研究了不同的焊接热输入对低合金高强钢ASTMA572GR.65钢在预热与不预热条件下焊接热影响区组织和性能的影响。研究表明,在小线能量(10kJ/cm)下,Nb(C,N)等第二相粒子在粗晶区能起到抑制晶粒长大的作用,使得晶粒比较小,而大线能量(40kJ/cm)下,这些粒子完全溶解,几乎没有起到对粗晶区晶粒长大的抑制作用。另外,小线能量(10kJ/cm)下,焊前预热有利于生成较细小的淬硬组织,对GR.65钢粗晶区的韧性起有利作用,而大线能量(40kJ/cm)下焊前预热反而使粗晶区组织粗大,并生成上贝氏体等韧性很差的组织,会对整个焊接热影响区产生不利影响。更多还原

【Abstract】 The influence of heat input on the microstructure and properties of heat affected zone in ASTM A572 GR.65 steel with and without preheating was investigated.The results show that,for a less heat input(10 kJ/cm),the grain size is not as large as that at a large heat input(40 kJ/cm),because the growth of coarse grain in heat affected zone(CGHAZ) is restricted by Nb(C,N) precipitates.The results indicate that the preheating joints before welding is benefit for toughness in the CGHAZ of GR.65 steel at low heat input,while the opposite effect is given at large heat input.更多还原