Q420M low-alloy high-strength steel with good welding performance and manufacturing method of Q420M low-alloy high-strength steel

The invention discloses Q420M low-alloy high-strength steel with good welding performance. The Q420M low-alloy high-strength steel comprises the following components in percentage by mass: 0.07-0.09% of C; 0.25 to 0.40 percent of Si; 1.50 to 1.60 parts of Mn; 0.025% to 0.040% of Nb; 0.20 to 0.30% of Cr; ti: 0.008 to 0.02%; the content of Als is 0.015 to 0.035 percent; less than or equal to 0.020% of P; s: < = 0.005%; h is less than or equal to 0.0002 ppm, N is less than or equal to 0.0080 ppm, and the balance is Fe and inevitable impurities. Wherein CEV is not more than 0.39%, and Pcm is not more than 0.20%. The Q420M low-alloy high-strength steel which is stable in mechanical property and has good low-temperature impact toughness and welding performance can be produced through the controlled rolling and DQ/ACC technology, and the steel plate has the good service safety characteristic. 一种焊接性能良好的Q420M低合金高强钢，包括如下质量百分比的各组分：C：0.07-0.09%；Si：0.25-0.40%；Mn：1.50-1.60；Nb：0.025-0.040%；Cr：0.20-0.30；Ti：0.008-0.02%；Als：0.