Effects of rare earth addition on microstructure of C–Mn steel

Abstract

The microstructures were observed in C-Mn steel and statistical analysis of the inclusions produced when trace amounts of rare earth were added to the steel. The results show that the content of intragranular acicular ferrite decreased in the order of being treated with La þ Ce/La/Ce in C-Mn steel after the treatment of different kinds of rare earths. The optimum mass ratio of La and Ce for La þ Ce combined treatment is 3:1.The best incubation time after Le þ Ce (3:1) treatment is 5 min. The size of inclusion nuclei favouring intragranular acicular ferrite nucleation concentrates in the range of 1-4 mm. The disregistries between rare earth inclusions and a-Fe are small, which plays an important role in rare earth inclusions inducing intragranular acicular ferrite nucleation.

Evolution of Calcium Aluminate Inclusions by Cerium Treatment in Al‐Killed Steel during Ruhrstahl–Heraeus Refining Process

“…[13][14][15] In recent years, rare-earth oxide metallurgy for improving welding performance are focused on by many researchers. [16] For the application of rare-earth oxide technology, it is very important to clear the evolution of oxide inclusions after rare-earth addition. The modification of alumina and spinel inclusions by rare earth has been reported very much.…”

Microstructure of Non‐Metallic Inclusions Identified in Cast Steel 42CrMo4 after Metal Melt Filtration by Novel Foam Filters

“…[1,2] The beneficial effect is known as "oxide metallurgy," where tiny dispersed non-metallic inclusions are used in a positive way as nucleation sites for intergranular ferrite leading to grain refinement. [3,4] On the other hand, nonmetallic inclusions can lead to many different quality problems. [5] Thus, entrapped non-metallic inclusions can cause internal cracks, slivers, or blisters in final rolled products.…”

“…Non‐metallic inclusions are an important subject in particular for steel makers, since they can have either a beneficial or a detrimental effect on the properties of their products . The beneficial effect is known as “oxide metallurgy,” where tiny dispersed non‐metallic inclusions are used in a positive way as nucleation sites for intergranular ferrite leading to grain refinement . On the other hand, non‐metallic inclusions can lead to many different quality problems .…”

Study on the Control of Rare Earth Metals and Their Behaviors in the Industrial Practical Production of Q420q Structural Bridge Steel Plate

“…The addition of lanthanide metals to continuously cast steel is particularly advantageous because of their ability to refine as-cast structures, reduce segregation, and increase hot ductility at temperatures just below solidification [9]. People studied the optimum mass ratio of La and Ce in La + Ce combined treatment, and the best incubation time of Le + Ce (3:1) treatment [10]. There were some works on the efficiency of Ti-bearing inclusions in refining the grain size, and dealing with Al and Mn contents in weld metal inclusions [11,12].…”