模拟焊后热处理对12Cr2Mo1R厚钢板冲击性能的影响

Effects of simulated PWHT on impact properties of 12Cr2Mo1R steel heavy plate

研究了模拟焊后热处理(PWHT)、阶段冷却热处理对临氢重整设备用12Cr2Mo1R钢厚钢板的组织和冲击性能的影响,试图建立厚钢板的组织与冲击韧性之间的联系。结果表明,采用正火(加速冷却)+回火生产的95mm厚12Cr2Mo1R钢板,显微组织以贝氏体为主,其中分布着一定数量的Cr、Mo析出相,具有良好的低温冲击韧性;经模拟焊后热处理和阶段冷却热处理后,基体组织未发生明显变化,有新的尺寸更小的析出相析出,其脆化指标VTr54+2.5ΔVTr54值为-97℃。经不同模拟热处理后,未明显变化的基体组织和晶粒内1～2μm的亚晶使厚钢板仍具有高的低温冲击韧性,母材中原有碳化物析出相和在不同模拟热处理条件下的新析出的细小碳化物相,未显示出对低温冲击韧性不利影响。

For establishing a relationship between the impact toughness and microstructures,the effects of simulated post weld heat treatment（PWHT） and step cooling heat treatment on the microstructures and impact properties of 12Cr2Mo1R steel heavy plate for hydrogen reforming equipment were studied.The results show that the 12Cr2Mo1R steel heavy plate with thickness of 95 mm which is processed by the normalization with accelerated cooling ＋ tempering has the microstructures of dominant bainite with some precipitation phases of chromium and molybdenum elements,and has good impact toughness at low temperature.After simulated PWHT and step cooling heat treatment,its microstructure has no obvious change and has some new smaller size precipitation phases,and its brittle value of vTr54＋2.5ΔvTr54 is-97 ℃.The unchanged microstructures of base metal and the existence of sub-grains with size of 1-2 μm after various simulated heat treatments still maintain its high impact toughness at low temperature.The original precipitated phases in base metal and new precipitated phases do not have negative effects on the low temperature impact toughness.