大型水轮机蜗壳用780MPa级高强钢焊接工艺研究
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摘要
为了解决大型水轮机用780MPa级高强钢焊接接头在焊后热处理后韧性降低的问题,对其焊接工艺进行了研究。通过冷裂纹试验,确定780MPa级高强钢预热温度达到100℃以上,能够有效避免焊接冷裂纹。在不同的线能量水平和不同的热处理温度下对接头性能进行了试验,焊态接头的线能量上限不宜超过4.0k J/mm。热处理态接头线能量的上限不超过3.8k J/mm,且使用550℃×4h的热处理规范,能够有效保证性能符合技术要求。按照ASME标准完成了大型水轮机用780MPa高强钢的焊接工艺评定,并在行业内首次实现了整体热处理的水轮机780MPa高强钢蜗壳等产品的制造。
The toughness of the 780 MPa grade high tensile strength steel welding joint is reduced after annealing heat treatment in the manufacture of hydropower volute,and the welding procedure was studied to solve the problem. Cold crack sensitivity experiments were conducted,results show that the 780 MPa grade high tensile strength steel should be heated above 100℃ before welding to avoid weld cold cracks. The mechanicalproperties of the weld joint were tested under different weld heat input levels and different post welding heat treatment conditions. Experimental results show that the maximum weld heat input for the as-weld joint should not exceed 4.0 kJ/mm,while it should not exceed 3.8 kJ/mm for the annealing heat treatment joint. The annealing parameter is recommended as 550℃×4 h to promise the mechanical properties of the weld joint. Welding procedure qualification of the 780 MPa grade high tensile strength steel is conducted following ASME standard,and all the test results are acceptable. For the first time in the hydropower equipment industry,the turbine volute and other products made by the 780 MPa grade high tensile strength steel are welded and annealed by Dong Fang Electric Machinery.
The toughness of the 780 MPa grade high tensile strength steel welding joint is reduced after annealing heat treatment in the manufacture of hydropower volute,and the welding procedure was studied to solve the problem. Cold crack sensitivity experiments were conducted,results show that the 780 MPa grade high tensile strength steel should be heated above 100℃ before welding to avoid weld cold cracks. The mechanicalproperties of the weld joint were tested under different weld heat input levels and different post welding heat treatment conditions. Experimental results show that the maximum weld heat input for the as-weld joint should not exceed 4.0 kJ/mm,while it should not exceed 3.8 kJ/mm for the annealing heat treatment joint. The annealing parameter is recommended as 550℃×4 h to promise the mechanical properties of the weld joint. Welding procedure qualification of the 780 MPa grade high tensile strength steel is conducted following ASME standard,and all the test results are acceptable. For the first time in the hydropower equipment industry,the turbine volute and other products made by the 780 MPa grade high tensile strength steel are welded and annealed by Dong Fang Electric Machinery.
引文
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[4]李少华,尹士科,刘奇凡.焊接接头强度匹配和焊缝韧性指标综述[J].焊接,2008,(1):24-27.LI Shaohua,YIN Shike,LIU Qifan.Review on Strength Matching of Welded Joint and Toughness Index of Weld[J].Welding&Joining,2008,(1):24-27.
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[6]杨军,吴鲁海,茅及放.低合金高强钢焊缝熔敷金属强韧化机理[J].焊接学报,2008,27(3):86-90.YANG Jun,WU Luhai,MAO Yifang.Mechanism of High Strength and High Toughness of Hsla Weld Deposited Metal[J].Transactions of the China Welding Institution.2008,27(3):86-90.