应变强化奥氏体不锈钢焊接接头冲击试验研究

Experimental study on impact behavior of austenitic stainless steel welding joints after cold stretching

为了研究9%应变强化工艺对焊接接头冲击性能的影响,给应变强化奥氏体不锈钢焊接接头冲击试验指标的制定提供依据,以奥氏体不锈钢S30408为研究材料,对9%应变强化前、后焊接接头焊缝区和热影响区的标准尺寸和5mm厚小尺寸夏比V型缺口试样进行-196℃低温冲击试验.研究结果表明:9%应变强化对冲击功与侧向膨胀量在统计学上无影响;试样的冲击功与侧向膨胀量均保持线性关系,且线性关系在应变强化前、后在统计学上无明显差异;除焊缝区标准试样外,其余试样在冲击功满足指标要求时,对应的侧向膨胀量也能满足指标要求;应变强化前、后小尺寸试样冲击功与标准尺寸试样冲击功比值在焊缝区内均大于0.5,在热影响区内均等于0.5.

The influence of 9 % cold stretching on impact behavior of welding joints was investigated to pro- vide the basis for establishment of eligible criteria on impact tests for austenitic stainless steel welding joints after cold stretching. Charpy V-notched impact tests of S30408 stainless steel welding joints in welds and HAZs before and after 9% cold stretching with two sizes of specimens （standard specimens and 5 mm sub-sized specimens） were conducted at --196 ℃. Experimental results showed no statistically significant difference between test groups before and after cold stretching. Meanwhile, linear relations between Charpy impact energy （Kv） and lateral expansion （Lε） with two specimen sizes were confirmed. No statis- tically significant difference was found in linear relations between test groups before and after cold stretc- hing. When Kv meets the requirement of standards and specifications, Lε also satisfies the requirements, except for standard specimens from welds. Relations of standard and sub-sized specimens Charpy impact energy were also discussed. Before and after cold stretching, the ratio of energy absorbed in sub-sized specimens to that in standard specimens is greater than 0.5 for welds, and equals to 0.5 for HAZs.