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模拟研究了Q550D低碳贝氏体钢焊接接头热影响区粗晶区冲击韧性受t_(8/5)(从800℃冷却至500℃的时间)影响的变化规律,并选取t_(8/5)为20 s时的热模拟条件研究焊后热处理工艺对粗晶区冲击韧性的影响,从而确定该钢的焊后热处理工艺。结果表明:Q550D钢粗晶区的冲击功随t_(8/5)的增加有下降趋势,在t_(8/5)≤30s时粗晶区冲击韧性保持较高水平;在250～600℃进行焊后热处理时母材的拉伸、冲击性能变化不大,粗晶区在350℃和550℃附近存在回火脆性,在500℃附近保持较高的冲击韧性;Q550D钢较佳的焊后热处理工艺为520℃×1.5h。
The impact of t_ (8/5) (time from 800 ℃ to 500 ℃) on the impact toughness of the heat affected zone (HAZ) of Q550D low carbon bainitic steel welded joints was simulated and the influence of t_ (8/5 ) For 20 s thermal simulation conditions of post-weld heat treatment process on the impact toughness of the coarse grain region, so as to determine the steel after-heat treatment process. The results show that the impact energy of the coarse grain region of Q550D steel decreases with the increase of t_ (8/5), and the toughness of the coarse grain region remains at a high level at t_ (8/5) ≤30s. At the temperature of 250-600 ℃, After heat treatment, the tensile and impact properties of the base metal did not change much. There was temper brittleness in the coarse-grained zone near 350 ℃ and 550 ℃ and high impact toughness at 500 ℃. The better post-weld heat treatment of Q550D steel Process is 520 ℃ × 1.5h.