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采用A002 , A132 和A302 三种焊条以及(600 ,800 和1050)0C×6h 三种焊后热处理方式,研究了304 钢不同焊缝的环境断裂行为。试验是用悬臂梁弯曲试样在室温0 .5mol/LNaCl+ 2 .5mol/LH2SO4 溶液中进行的。测定了各种焊缝的da/dt ~K1 曲线,并作了浸蚀试验、腐蚀电化学试验和断口分析。结果表明:焊缝的KISCC 为30 ~38MPam 1/2,按A002,A302 和A132顺序递增,只及母材的(62 ~79)% ;其裂缝扩展速率da/dt 达(5 ~7) ×10- 6 m ms- 1 ,为母材的2 .8 ~3 .9 倍。随焊后热处理温度升高,da/dt 下降, KISCC 升高。304 母材的环境断裂受应变产生活性通道机理控制;而焊缝主要受预存活性通道机理制约,以沿晶断裂为主,所需KISCC 较低,da/dt 较大。在焊缝中,铁素体呈阳极而优先溶解,其数量越多,越易呈半连续或连续的网状,意味着预存活性通道越通畅,环境断裂敏感性越高。焊缝成分和焊后热处理的影响,实际上都是通过改变铁素体的数量和形态而起作用的
Three types of welding electrodes, A002, A132 and A302, and 0C × 6h (600, 800 and 1050) three kinds of post-weld heat treatments were used to study the environmental fracture behavior of different welds in 304 steel. The test is to bend the specimen with a cantilever beam at room temperature. 5mol / LNaCl + 2. 5mol / LH2SO4 solution. The da / dt ~ K1 curves of various welds were measured, and the erosion test, corrosion electrochemical test and fracture analysis were conducted. The results show that the KISCC of weld is 30 ~ 38MPam 1/2, increasing in order of A002, A302 and A132, only increasing from 62% to 79% of the base metal. The crack propagation rate da / dt is about 5 ~ 7 × 10-6 mms-1, 2 for base metal. 8 ~ 3. 9 times. With the post-welding heat treatment temperature, da / dt decreased, KISCC increased. The fracture of 304 base metal is controlled by the active channel mechanism of strain generation. However, the weld is mainly controlled by the mechanism of pre-existing active channels, mainly by intergranular fracture, with lower KISCC and larger da / dt. In the weld, the ferrite anode preferentially dissolved, the greater the number, the more likely to be semi-continuous or continuous mesh, which means that the more pre-activated active channel, the higher the sensitivity of environmental rupture. The composition of the weld and the effect of the post-weld heat treatment actually work by changing the amount and morphology of the ferrite