Effect of Ti,Zr and Mg addition on inclusions and the impact toughness of heat affected zone in low carbon steel

In order to understand the effects of titanium,zirconium and magnesium on inclusions and the impact toughness of heat affected zone（HAZ） of steel,four low carbon steels deoxidized by titanium,zirconium and magnesium were obtained.After melting,forging,rolling and welding simulation,the inclusion characteristics （size,distribution,morphology and chemistry） analysis,Charpy-type test and the fracture observation of the specimens after the Charpy-type test were carried out respectively.The following results were found.A linear relationship exists between inclusions density and Ti content when Ti content ranges from 0.004%to 0.032% without Mg,and the proportion of inclusions in diameter less than 0.5μm decreases with the increasing of Ti content in steel.The density of inclusion increases rapidly when adding Ti-Zr-Mg deoxidant.The addition of Ti-Zr-Mg can enhance the impact toughness of HAZ after welding simulation.The maximal impacting energy after welding simulation is 249 J at 253 K.The complex particles of MgO-ZrO₂-TiO_x-MnS are most benefit to enhance impact toughness.     

P460NL1钢SH—CCT图的测定

通过热模拟手段获得P460NL1钢的焊接热影响区组织，采用热膨胀法测定出了该钢的焊接热影响区连续冷却曲线（SH－CCT）图，从而进一步地完善了该钢的技术资料。     

Effect of boron and phosphorus on HAZ microfissuring of Allvac 718 Plus superalloy

Abstract

Heat affected zone (HAZ) microfissuring was investigated in electron beam welds of two Allvac 718 PLUS (718 Plus) alloys with different boron and phosphorus contents. Two preweld solution heat treatments were used and microfissuring susceptibility was evaluated by measuring the HAZ crack lengths in both alloys after bead on plate welding. The segregation behaviour of boron and phosphorus was studied before and after welding by secondary ion mass spectrometry (SIMS). Hot ductility behaviour of the alloys in the standard solution preweld heat treatment was also examined. The results of crack measurements, segregation studies and hot ductility tests correlated well with each other. It was observed that besides constitutional liquation of Nb rich MC type carbides, segregation of B and P largely influenced the microfissuring susceptibility of the alloy. Heat affected zone microfissuring increased with an increase in B + P concentrations and with an increase in the preweld solution heat treatment temperature. Segregation behaviour of B and P and its contribution to microfissuring in Allvac 718 Plus alloy were discussed.     

Characterization of the microstructure and hardness of the HAZ in a 800MPa grade RPC steel

0Introduction Intheprojectof“NewGenerationSteelMaterials”, oneoftheeffectiveapproachestoachieve800MPagrade steelsistoadoptRPCphasetransformationtechnique[1]. Atpresent,12 millimeter thickplatesteelwithyield strengthover800MPahasbeenobtainedbymeansofthis…     

Numerical simulation of the liquating behavior of niobium carbide in heat-affected-zone during welding of a superalloy

In order to predict the propensity of a superalloy to heat-affected-zone (HAZ) liquation cracking, Visual FORTRAN procedures were developed based on a heat transfer and mass diffusion model and the constitutional liquation of precipitate (NbC) at grain boundaries was simulated numerically. The results show that with the increase in the rate of welding thermal cycle, the solid dissolution of precipitate prior to liquation decreases and the thickness of liquid film produced by constitutional liquation increases. Higher heating rate inhibits the further melting of adjacent matrix and the solidification of liquid by liquid-to-γ mode in the subsequent thermal cycle. As a result, the residual liquid film still maintains a great thickness at the moment when temperature is down to the eutectic point, which will promote HAZ micro-fissuring. Finally, hot ductility tests on a low-expansion superalloy were performed to verify indirectly the conclusions drawn from the numerical simulation.     

Fatigue crack growth behavior of heat affected zone in P92 steel weldment

In this study, the effect of microstructure on fatigue crack growth behavior of HAZ was investigated using newly developed P92 steel weldment. Fatigue crack growth rates of the fusion line and fusion line+2 mm in HAZ were found to be faster than that of welds or base metal, while fatigue crack growth rate of the fusion line+1 mm was the slowest. The fracture appearance of the fusion line and fusion line+2 mm revealed mainly transgranular, cleavage-like faceted fracture surfaces and the fusion line+1 mm showed quasi-cleavage fractures with scattered dimples, which increased resistance to fatigue crack growth.     

中心偏析对连铸钢及其HAZ冲击性能的影响

研究了中心偏析对连铸10CrNi3MoV钢钢板及其焊接接头HAZ表面和心部冲击性能的影响,试验结果表明,中心偏析恶化了中心位置钢板及其HAZ的冲击性能;板厚中心位置试样的冲击功相对于表面位置的有一定下降,下降幅度随试验温度的降低有增大趋势。     

含铌细晶粒钢的热影响区组织性能

讨论了以形变诱导相变为主的超细晶粒钢在添加合金元素铌以后热影响区组织性能的变化.试验结果表明:添加少量铌以后,粗晶区的韧性有所改善,但不能阻止母材晶粒的长大,韧性的下降不可避免,在实际焊接时,应避免过小的焊接热输入.     

HQ1080钢的焊接工艺

对HQ1080钢焊接热影响区的组织转变规律、冷裂纹敏感性及热影响区韧性进行了试验研究,在此基础上制定了HQ1080钢焊接工艺,为HQ1080钢的焊接工程应用奠定基础。     

核电用SA508Gr.3钢落锤试验分析

运用扫描电镜、光学显微镜等检测手段对SA508Gr.3钢落锤试样的断口形貌和焊道热影响组织进行对比观察与分析,结果表明：落锤试样断口形貌与组织呈现出良好的对应关系,而且落锤试样的热影响区的组织韧性优于母材,并没有对母材产生不利影响。