One kind of yield ratio ≤0.65 mobile offshore platform and method of producing steel

One kind of yield ratio steel ≤0.65 mobile offshore platform, according to the thickness of the finished component and wt% as follows: a thickness of 8 ~ 50mm, C: 0.08 ~ 0.12%, Si: 0.20 ~ 0.35%, Mn: 1.10 ~ 1.60%, P: ≤0.018%, S≤0.008%, Ni: 0.10 ~ 0.20%, Mo: 0.07 ~ 0.17%, Ti: 0.005 ~ 0.015%, Als: 0.015 ~ 0.035%, N: ≤0.008%; thickness greater than 50 to 80mm sizes, C: 0.08 ~ 0.12%, Si: 0.20 ~ 0.35%, Mn: 1.10 ~ 1.60%, P: ≤0.010%, S≤0.004%, Ni: 0.10 ~ 0.20%, Cr: 0.10 ~ 0.20%, Mo: 0.07 ~ 0.17%, Ti: 0.005 ~ 0.015%, Als: 0.015 ~ 0.035%, N: ≤0.008%; production steps: The smelting and casting into a billet; heating the slab to; rough rolling; rolling; cooling; normalized; cold mist to be ≥50 to a thickness of 80mm. The present invention yield ratio ≦ 0.65, integrated stable performance and excellent welding performance, can meet the requirements of mobile offshore platform steel.