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通过试验分析及焊接过程仿真相结合的方式,系统分析了固体发动机D406A钢金属壳体支座焊接裂纹产生的原因。结果表明:D406A钢固体发动机金属壳体支座角焊缝熔合区组织主要是针状马氏体,相比其它区域,显微硬度最高,冲击韧性最低,淬硬性最大,是整个接头最薄弱的区域。由于该处同时为接头应力最集中的区域,增大了熔合区处开裂的敏感性,从而导致支座角焊缝沿熔合线开裂。
Through the combination of experimental analysis and welding process simulation, the reason of welding crack in solid shell engine D406A steel shell was systematically analyzed. The results show that the microstructure of fillet welds in the metal shell bearing of D406A steel is mainly acicular martensite. Compared with other regions, the microhardness is the highest, the impact toughness is the lowest and the hardenability is the highest, which is the weakest of the whole joint area. Since this zone is also the area where the joint stress is most concentrated, the sensitivity of cracking at the fusion zone increases, resulting in cracking of the bearing fillet along the weld line.