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1. (WO2018036379) LOW-COST, HIGH STRENGTH-TOUGHNESS THIN GAUGE 9NI STEEL PLATE MANUFACTURING METHOD

Pub. No.:    WO/2018/036379    International Application No.:    PCT/CN2017/096427
Publication Date: Fri Mar 02 00:59:59 CET 2018 International Filing Date: Wed Aug 09 01:59:59 CEST 2017
IPC: C22C 38/02
C22C 38/04
C22C 38/08
C22C 38/12
C22C 38/06
C21D 8/02
Applicants: NANJING IRON & STEEL CO., LTD.
南京钢铁股份有限公司
Inventors: SUN, Chao
孙超
LI, Donghui
李东晖
YIN, Yuqun
尹雨群
WANG, Congdao
王从道
ZHAO, Ronggui
赵荣贵
Title: LOW-COST, HIGH STRENGTH-TOUGHNESS THIN GAUGE 9NI STEEL PLATE MANUFACTURING METHOD
Abstract:
Provided is a method for manufacturing a low-cost, high strength-toughness thin gauge 9Ni steel plate. Weight percentages of a molten steel composition are: C: 0.03-0.06%, Si: 0.1-0.2%, Mn: 0.5-0.8%, Ni: 8.6-9.1%, Mo: 0.02-0.05%, Als: 0.015-0.035%, S≤0.005%, P≤0.007%, N≤0.007%, and a balance being Fe and non-removable impurities. The molten steel is smelted and alloyed using a vacuum furnace with vacuum degree ≤50Pa, with heating temperature at 1160-1220℃, holding time for 90-180min, and billet thickness after cogging down of 120-150mm; adopting a two-stage controlled rolling; waiting the temperature for 10-15s after rolling; accelerate cooling to 440-550℃ at a cooling rate of 15-40℃/s, and then air-cooling to room temperature; and the steel plate is heated to 575-605℃ for tempering for 45-70min and then air cooled to room temperature. The method utilizes the properties of 9Ni steel material and the cooling characteristics of the thin gauge steel plate, combines the controlled rolling and cooling with the heat treatment process, thereby improving the performance of materials at the same time shortening the process and reducing process energy consumption, so as to achieve the purpose of reducing the production cost of high strength-toughness thin gauge 9Ni steel plate.