Microstructure and Obdurability Improvement Mechanisms of the La‐Microalloyed H13 Steel

Abstract

Rare earth microalloying is one of the most important methods to improve the mechanical properties of die steels. This paper investigates the relationships among addition of La, microstructure, and mechanical properties of H13 steel. The influences of following factors on obdurability improvement of La‐microalloyed H13 steel, such as grain refinement, deoxidization and desulphurization, grain boundary. and precipitations, have been studied. The results indicate that with the increase of La content in the range of 0–0.45 wt%, the primary dendritic spacing and average grain size of as‐cast samples decrease at the beginning and then increase. The tensile strengthtrue(normalσnormalbtrue), yield strengthtrue(normalσnormalstrue), and impact toughnesstrue(normalαnormalktrue) of hot‐forged samples after quenching and tempering treatments increase at the beginning and then decrease with the increase of La content. The mechanical test results indicate that with 0.03 wt% La content, the obdurability of hot–forged H13 steel after quenching and tempering treatments increases obviously. As compared with La‐free H13 steel, the normalσnormalb and normalσnormals of hot‐forged H13 steel containing 0.03 wt% La increase by 5.0% and 4.6%, normalαnormalk increases by 67.8% from 29.0 to 48.7 J·cm−2. La‐microalloyed effect is attributed to grain refinement, La2O2S precipitations and dislocation density of H13 steel.

Effects of cerium addition on the microstructure, mechanical properties and strain hardening behavior of TWIP steel Fe-18Mn-0.6C

“…Staggered deformation twins may be formed by stacking faults emitted from grain boundaries. Due to the reduction of the SFE in rare earth microalloying steels, rare earth elements cause an increase in the dislocation density and promote the formation of twins [45,46]. The main assumption of the model originally proposed by Olson and Cohen [47] is that a stacking fault in an fcc crystal structure is basically a thin layer of hexagonal close-packed (hcp) phase, separated from the matrix by a phase boundary on each side.…”

Evolution of Inclusions after Cerium and Titanium Addition in Aluminum Deoxidized Fe-17Cr-9Ni Austenitic Stainless Steel

“…[17][18][19] Moderate addition of rare earth elements also plays an important role in improving the performance of steel product. 20) When the content of Ce was between 0.01% and 0.1%, the Ce-bearing austenitic stainless steel exhibits good antibacterial properties. 21) However, excessive addition of Ce can also has a harmful effect on steel products by affecting the type and quantity of inclusions.…”

Effects of Rare Earth Elements on Microstructure and Mechanical Properties of H13 Die Steel

“…In addition, the segregation of RE purified the boundaries, thereby increasing the boundary strength. Moreover, RE can change the fracture mode (i.e., from intergranular fracture to transgranular fracture [27]). This resulted in hindering the migration of grain boundaries in the tensile process and improved grain boundary resistance to crack formation and propagation in the RE-H13 die steel and correspondingly, improved hardness and UTS of the steel.…”