Usually, tool steels are used in quenched and tempered conditions. Due to the phase transition from austenite martensite volume change during transformation, controlling distortion might be challenging. A newly developed steel focusing on a bainitic structure, even for bigger dimensions, shows lower hardness at ambient temperature than conventional hot working but with dependency. Therefore, se...

This research shows two new microalloyed steels with niobium (Nb) for railroad wheels (Nb1 and Nb2) applied on heavy haul transportation (load over 30 tons/axle). The have mixed microstructure composed of pearlite bainite (finished wheel rim section), another one martensite (black section removed machining) obtained by continuous cooling quenching heat treatment followed tempering. bainitic mar...

Displacive stress and strain induced transformations are those that occur when the formation of martensite or bainitic ferrite is promoted by application strain. These have been shown to be one mechanisms which mechanical properties a microstructure can improved, as they lead better ductility strength transformation plasticity effect. This review aims summarize fundamental knowledge about them,...

1 緒 言 工具や軸受,ゲ ージなどの精密部品では残留オーステ ナイ ト(rR)が存在すると硬 さや疲労寿命の低下,切 削性 不良あるいは経年形状変化を招きそれらの性質に有害な 影響をもたらす.そ れゆえ,こ れ らに使用する鋼では rRを 極力減少させ るのが好 ましい.し か しなが ら,rR が低合金構造用鋼に存在する場合には延性やじん性が向 上するとともに低温におけるぜい性破壊の防止に役立つ 場合が多い.そ れゆえ,最 近進んで熱処理によって人 為的にrRの 量や存在形態を調整 し混合組織 として優れ た機械的性質 を得ようとす る研究が しばしば見受 けら れ1)~6)る.こ のようなrRを 積極的に利用 しようとする方法 として,近 年Si-Mn鋼 をベイナイ ト変態させるオース テンパー処理が注 目されている. Si-Mn鋼 をベイナイ ト変態 させた場合多量のrRが ...

In the first part of the present study, two steels were designed with the aim of achieving properties consistent with the specifications for the manufacture of seamless pipes. The alloys were intended to develop into mixtures of bainitic ferrite and carbon enriched retained austenite during cooling to ambient temperature from the pipe forming operations, thus avoiding the need for subsequent he...

The paper focuses on the analysis of initiation and propagation CO 2 corrosion in several samples low-alloy steel with different microstructures using scanning electrochemical microscopy (SECM) other techniques. It is found that rate mode are highly sensitive to microstructure. overall current density much higher more uniformly distributed for tempered martensite structure than having either a ...

Abstract Electron beam powder bed fusion (E-PBF) is a well-known additive manufacturing process. Components are realized based on layer-by-layer melting of metal powder. Due to the high degree design freedom, came into focus tooling industry, especially for tools with sophisticated internal cooling channels. The present work focuses relationships between processing, microstructure evolution, ch...