BWELDY960Q钢焊接热模拟热影响区组织与性能

Microstructure and properties in heat affected zone of BWELDY960Q steel by welding thermal simulation test

采用焊接热模拟技术模拟BWELDY960Q钢焊接热影响区,在不同峰值温度条件下,研究热影响区各区域组织与性能的变化规律.结果表明,热影响区各微区组织形态不同,粗晶区的组织为板条状马氏体,细晶区的组织为细晶板条马氏体,不完全重结晶区的组织为马氏体、索氏体和铁素体的混合组织,回火区组织为回火索氏体.峰值温度达到1 200℃时,热影响区原始奥氏体晶粒已经开始粗化,并越接近熔合区,晶粒粗化现象越显著.粗晶区冲击韧性较低,韧性损失为母材的82.17%,不完全重结晶区的冲击韧性损失为母材的46.53%.模拟焊接热影响区组织比实际焊接热影响区组织更粗大.

Thermal physical simulation test was carried out to simulate heat-affected zone of BWELDY960 Q steel.Under different peak temperature, the change of microstructure and properties were studied. The results show that each microzone in heat-affected zone has different structure form. It exhibits lath martensite in coarse grained region, and fine lathe martensite in fine grained region, martensite and sorbite in incomplete annealed zone, tempered sorbite in tempered zone,respectively. Original austenite grain begins coarsening when peak temperature reaches 1 200 °C, coarsening phenomenon becomes more significant, while the zone is close to fusion line. Impact toughness of coarse grained zone is decreased by82.17% of the base metal, it is also found that the toughness loss of intercritical heat affect zone is 46.53%. Compared with the practical welding, heat affected zone obtains more coarse microstructure after welding thermal simulation test.