Changzhong WU
,
Huaining CHEN
,
Jing CHEN
,
Quanhong LIN
材料科学技术（英）
The explosion treatment technique has been used in the relief of residual stresses in 800 MPa grade high strength steel manual welded joints. The residual stresses on surface and through thickness of the weldment were measured for both as-welded and explosion-treated sample, the mechanical properties of welded joints under different conditions were also tested. The effect of explosion treatment on the fracture toughness of materials with a residual defect was investigated by crack opening displacement (COD) test. The results show that explosion treatment can reduce not only the surface residual stress but also the residual stress through thickness in the welded joints. The effect of explosion treatment on the mechanical properties and a residual defect in welded joint were inconspicuous.
关键词:
High strength steel
,
爆炸处理
,
残余应力
,
接头力学性能
,
CO
Byung-Hui Choi
,
Byung-Ki Choi
材料科学技术（英）
As the aircraft and aerospace industry and the automobile industry are developed, the demand of reliable materials with high strength and high toughness is steadily increased. The grain miniature method which improves the ductility and the toughness simultaneously under high strength is the miniature of the casting microstructure. In this paper, the Nb which affects the austenite grain miniature is added by 0.00%, 0.03% and 0.06% in this steel and the ingot is manufactured in a vacuum induction melting furnace (VIM). The casting microstructure and the mechanical property of the maraging steel according to Nb contents are analyzed by conducting the solution annealing and the age hardening after hot rolling. In this result, a specimen containing 0.03% Nb is most miniature. When it does the long time age hardening, the precipitation estimated as the carbide is appeared. The mechanical properties are excellent if a specimen containing 0.06% Nb does the age hardening during 8 h in 482°C.
关键词:
High strength steel
,
null
,
null
,
null
Yajiang LI
,
Zengda ZOU
,
Dezhen LIU
,
Huiqiang WU
,
Juan WANG
材料科学技术（英）
Cracking morphology in the fusion zone of HQ130 high strength steel was researched by "the y-silt test" and "three point bend test", ultrasonic test and microscope. HQ130+QJ63 high strength steel was welded by Ar+CO2 gas shielded arc welding under the condition of no-preheat. Experimental results indicated that welding crack produced in the partially melted zone of the weld root of HQ130 steel side and propagated parallel to the fusion zone. The cracking developed alternatively between the weld and the partially melted zone, and is not strictly to rupture at W/F boundary surface. Controlling weld heat input (E) about 16 kJ/cm could make the cracking rate to be lowest and satisfy the performance requirement of welded joint zone.
关键词:
High strength steel
,
null
,
null
