The Study On Weld Formation And Corrosion Resistance Of 1Cr18Ni9Ti Stainless Steel Ultra-narrow-gap Welding Joint With Φ2.0mm Wire

Austenite stainless steels is widely used in many fields, such as nuclear industry, aerospace, biology and medical science etc, for its good mechanical property, well resistance property of intergranular corrosion, excellent welding ability and biological compatibility. However, in engineering application, as the limitation on controlling heat input of the traditional welding methods, austenite stainless steels welding joints easily occur intergranular corrosion for the chromium depletion, and lead to the decrease of resistance property of corrosion. UNGW can vastly reduce the heat input as the gap is less than 6mm, and has special advantage in improving welding ability and resistance property of corrosion of austenite stainless steel thin plate.In this article, a series of ultra-narrow gap weld 1Cr18 N i9Ti stainless steel plate experiments is done which with Φ2.0mm wire and ultrafine particle constraint arc, and studied the effect of the voltage and the current on weld formation, structure and the resistance property of intergranular corrosion. The results of welding forming shows that if the voltage is between 25 V and 33 V, as well, the current changes from 210 A to 320 A, could get well formed welds. But if the voltage and the current is out of the extent, the welds formation situation are either "the side wall lack of fuse" or "the arc rising". Observe the structure of different double bead samples shows that : when the heat input is about 0.84kJ/mm, the structure of the first bead is equiaxed grain, while the structure of the second bead is almost the bulky column grain; when the heat input is about 1.13 kJ/mm, the structure of the first bead is equiaxed grain, as well, but the structure of the second bead is refining, and there are mixed up with few equiaxed like grains; when the heat input is about 1.28 k J/mm, the structure of the first bead is still equiaxed grain, however the structure of the second bead transit from column grain to equiaxed grain. Observe the immersing etch feature under the SEM indicates that as the increase of heat input, the corrosion of different welds transit from nonuniform to uniform. But there is no significant difference between the HAZ of each samples. Calculate the corrosion rate declare that the resistance property of corrosion of the welds which we got is better than the basement.In conclusion, with Φ2.0mm wire and ultrafine particle constraint arc ultra-narrow gap weld 1Cr18 N i9Ti stainless steel can get the well formed welds and have fine resistance property of corrosion.