焊后热处理对Q235堆焊复合板的冲击性能影响

Effects of Postweld Heat Treatment on Impact Properties of Q235 Overlaying Composite Board

目的研究热处理温度对Q235堆焊复合板的冲击性能影响。方法采用THD212铬钼钢焊条堆焊的方法制备高强度和高耐磨的复合板,对Q235复合板分别进行850,900,950℃、保温15 min的淬火处理,探讨堆焊后的热处理温度对复合板微观组织和冲击性能的影响。结果随着淬火温度的升高,复合板冲击韧性先升高后降低,在900℃淬火处理时冲击功最大,为75.0 J;在950℃淬火时冲击功最小,为19.4 J。微观组织分析发现,当淬火温度在850和900℃时,堆焊层出现塑性和韧性较好的针状位错马氏体,在一定程度上提高焊接接头的韧性,断口形貌也表现出显著的韧性断裂特征;当淬火温度为950℃时,随着奥氏体化温度升高,淬火后获得脆性粗大条状马氏体组织,显著降低韧性,焊缝区和高强堆焊区均为脆性断裂。结论在焊后进行一定温度范围内的热处理方法可以提高Q235堆焊复合板的冲击韧性。

This paper aims to research the effect of heat treatment temperature on impact properties of Q235 overlaying composite board. High strength and wear resistance composite plates were prepared by surfacing with THD212 chromium molybdenum electrode. Quenching treatment at different temperatures（850, 900, 950 ℃） was carried out, the microstructure and impact toughness of the composite plate were studied. The impact toughness trend of composite plate first increased and then decreased with the rise of quenching temperature. The toughness of after 900 ℃ quenching was the largest（75.0 J）, and the toughness of after 950 ℃ quenching was the lowest（19.4 J）. There was a large number of massive brittleness strip martensite in the matrix after quenching at 950 ℃, but dislocated martensite in microstructure after quenching at 800 ℃ and 900 ℃. It improved the toughness of welded joint and ductility of fracture morphology to a certain extent. The fracture mechanism of weld zone and high strength surfacing zone after 950 ℃ quenching was brittle fracture. The impact toughness of Q235 surfacing composite plate can be improved by controlling the heat treatment after welding.