Abstract: The L450M pipeline steel (/% ：0. 06C, 1.52Mn,0. 19Si,0. 017Ti,0.048Nb,0. 028Als) has obtained good strength and toughness by control of compression ratio, reduction ratio and rolling temperature. The results reveal that the high reduction rate of more than 20% in the last three passes of 200 mm slab rough rolling and the first three passes of finish rolling can make the 12 mm steel plate to form fine micron grain during the subsequent cooling process. The grain size is basically below 10μm, and some grains can be refined to below 2 μm. The yield strength of pipeline steel can reach above 500 MPa and the transverse impact energy at -15 ℃ can reach over 300 J by the compression ratio of finishing rolling 3.5, finishing rolling starting temperature at 930 ~ 950 ℃ and finishing temperature at 810 ~ 830 ℃. The yield ratio of steel can be effectively reduced by increasing rough rolling temperature to ≥1 040 ℃, reducing compression ratio to ≤ 3.8 and increasing finish rolling temperature to ≥800℃ etc.

摘要： 通过对压缩比、压下率和轧制温度的控制,使L450M管线钢（/%:0.06C,1.52Mn,0.19Si,0.017Ti,0.048Nb,0.028Als）获得了良好的强韧性。结果表明,200 mm坯粗轧末3道次和精轧前3道次达到20%以上的大压下率,可以使12 mm钢板在随后的冷却过程中形成细小的微米级晶粒。晶粒尺寸基本达到了 10μm以下,部分晶粒可以细化至2 μm以下。采用3.5倍左右的精轧压缩比,930-950℃的精轧开轧温度,810~830 ℃的精轧终轧温度,管线钢的屈服强度达到500 MPa以上,同时-15℃横向冲击功可以达到300 J以上。通过适当提高粗轧温度至≥1 040℃,降低精轧压缩比至≤3.8和提高精轧终轧温度至≥800℃等可以有效地降低钢材的屈强比。

关键词: 细晶强化, 超细晶, 屈强比, L450M管线钢, 低温韧性