焊接热循环对10Ni5CrMoV钢组织的影响

Influnce of Weld Thermal Cycle on Microstructures of 10Ni5CrMoV Steel

采用模拟焊接热循环的方法，研究了不同峰温和ｔ＿（８／５）条件下１０Ｎｉ５ＣｒＭｏＶ钢热影响区组织的变化。金相观察发现，峰温在Ａｃ＿１～Ａｃ＿３之间时，其组织为细小的马氏体和高温回火马氏体的混合组织；峰温超过Ａｃ＿３时，冷却后均转变为马氏体，且发生自回火现象。峰温越高，奥氏体晶粒越粗大，冷却后形成的马氏体板条束尺寸也越大。随着ｔ＿（８／５）的增加，其组织由自回火马氏体（含少量孪晶马氏体）、自回火马氏体＋下贝氏体、自回火马氏体＋下贝氏体＋上贝氏体、下贝氏体＋上贝氏体，最后形成以上贝氏体为主的组织。

By weld thermo-simulation test with different peak temperatures and t_(8/5),the variatio n o f HAZ microstructures of 10Ni5CrMoV steel was studied.The metallographic observation revealed that when the peak temperature was between Ac_1～Ac_3,a mixture microstructure with fine martensite and tempering martensite of high temperaturewas obtained, moverover auto-tempering martensite was produced. When the peak temperature over Ac_3,the HAZ microstructures were completely trans formed to martensite after cooling. The higher the peak temperature, the coarser the grain size of prior austenite, the larger the martensitic lath bundle after phase transformation.It was also found that with t_(8/5) increasing the microstructure change from auto-tempering martensite (containing a little transformation twin),auto-tempering martensite + LB,auto-tempering martensite +LB +UB, LB +UB, to the final microstructure in which UB vasts majority was formed.