Abstract: The manual arc welding and CO₂ shielding gas arc welding of 3. 8 mm DP590 steel sheet (/% ： 0. 07C, 0. 45Si, 1.61Mn) are carried out respectively by Φ3 mm E4303 carbon steel welding rod (/% : ≤0. 12C, ≤0. 25Si, 0. 30 〜0. 60Mn) and Φ 1 mm H10MnSi welding wire (/% : 0. 14C, 0. 65 ~0. 95Si, 0. 80 ~ 1. 10Mn) with different welding parameters, and the structure and microhardness of welding zone are observed and analyzed by ZEISS optical microscope and LEICA microhardness meter. Results show that in welding metal zone the structure of steel by manual welding is proeutectoid ferrite and pearlite distributed along columnar crystal and that by CO₂ shielding gas welding is acicular ferrite and minor bainite； in coarse grain region the structure of steel by manual welding is bainite and proeutectoid ferrite, and that by CO₂ shielding gas welding is lath martensite and bainite, of which the grain size is larger than that by manual welding ；with CO₂ shielding gas welding as using larger heat input the Widmannstatten structure in welding metal and coarse grain region is eliminated; the maximum of microhardness is occurred at coarse grain region and the width of heat affected zone of welding steel by manual arc welding is less than that by CO₂ shielding gas welding.

摘要： 在不同焊接参数下分别通过Φ3 mm E4303碳钢焊条(/%:≤0.12C、≤0.25Si、0.30～0.60Mn)和Φ1mm H10MnSi焊丝(/%:0.14C、0.65～0.95Si、0.80～1.10Mn)对3.8 mm DP590钢薄板(/%:0.07C、0.45Si、1.61 Mn)进行手工电弧焊接和CO₂气体保护焊接,并利用ZEISS光学显微镜、LEICA显微硬度计分别对焊接接头的组织和显微硬度进行了观察和分析。结果表明,在焊缝区手工电弧焊焊缝组织为沿柱状晶分布的先共析铁素体和珠光体,CO₂气体保护焊为针状铁素体和少量贝氏体,在粗晶区手工电弧焊为贝氏体和先共析铁素体,CO₂气体保护焊为板条马氏体和贝氏体,且其粗晶区晶粒尺寸大于手工电弧焊;采用CO₂气体保护焊,选择较大的热输入,焊缝和粗晶区的魏氏组织消失;显微硬度最大值均出现在粗晶区,手工电弧焊的热影响区宽度小于CO₂气体保护焊。

关键词: DP590钢板, 手工电弧焊接, CO₂气体保护焊接, 焊接区, 组织