智能型耐火钢焊接热影响区高温拉伸性能研究

Study on high temperature tensile strength of heat-affected zone in welding of intelligent fire-resistant steel

采用热模拟的方法模拟智能型抗震耐火钢Q420FRE的焊接热影响区,并进行600℃的高温拉伸实验。在经受高温拉伸的过程中,单道次的高温拉伸强度在粗晶区最高,逐渐向细晶区和不完全重结晶区降低,到未相变区又升高。双道次焊接热影响区也呈现相同的规律。随着焊接热输入的提高,焊接热影响区粗晶区的高温拉伸强度降低。在焊接热循环作用下,碳氮化物(Nb,Ti)(C,N)的溶解、长大和粗化引起了焊接热影响区不同区域高温拉伸强度的差异。

The welding heat affected zone（HAZ） of intelligent fire-resistant steel is simulated by Gleeble 3800 thermal simulator,and the high temperature tensile strength test is made at 600 ℃. During the high temperature tensile process, the highest tensile strength occurs in the coarse grained region by single thermal cycling,and then the tensile strength gradually decreases from fine grained region to recrystallized zoue,but increases in untrausformed zone. The welding HAZ shows same law of tensile strength at high temperature by double thermal eycling. As the welding heat input increases,the tensile strength at high temperature in coarse grained HAZ decreases. Because of the influence nf welding thennal cycling, the dissolution, growth and coarsening of carbonitride（ Nb,Ti）（ C, N ） cause the difference between tensile strengths in different regions of HAZ at high temperature.