Simultaneously Enhanced Strength, Toughness and Ductility of Cast 40Cr Steels Strengthened by Trace Biphase TiCx-TiB2 Nanoparticles

Abstract

Simultaneously improving the strength, toughness, and ductility of cast steels has always been a difficult problem for researchers. Biphase TiCx-TiB2 nanoparticle-reinforced cast steels are prepared by adding in situ nanosized biphase TiCx-TiB2/Al master alloy during the casting process. The experimental results show that a series of significant changes take place in the microstructure of the steel: the ferrite-pearlite structure of the as-cast steels and the bainite structure of the steels after heat treatment are refined, the grain size is reduced, and the content of nanoparticles is increased. Promotion of nucleation and inhibition of dendrite growth by biphase TiCx-TiB2 nanoparticles leads to a refinement of the microstructure. The fine microstructure with evenly dispersed nanoparticles offers better properties [yield strength (1246 MPa), tensile strength (1469 MPa), fracture strain (9.4%), impact toughness (20.3 J/cm2) and hardness (41 HRC)] for the steel with 0.018 wt.% biphase TiCx-TiB2 nanoparticles, which are increased by 15.4%, 31.2%, 4.4%, 11.5%, and 7.9% compared with the 40Cr steels. The higher content of nanoparticles provides higher strengths and hardness of the steel but are detrimental to ductility. The improved properties may be attributed to fine grain strengthening and the pinning effect of nanosized carbide on dislocations and grain boundaries. Through this work, it is known that the method of adding trace (0.018 wt.%) biphase TiCx-TiB2 nanoparticles during casting process can simultaneously improve the strength, toughness, as well as ductility of the cast steel.

Microstructure and Tensile Properties of Graphite Ductile Iron Improved by Minor Amount of Dual‐Phased TiC–TiB2 Nanoparticles

“…The 0.01 and 0.02 wt% TiC–TiB 2 nanoparticles were added in the molten DI according to the findings of a previous study. [ 25 ] The chemical compositions of the DI specimens studied herein were measured using a carbon–sulfur analyzer and an optical spectrometer, as displayed in Table 1 .…”

Application of nanoparticles in cast steel: An overview

“…In authors' previous work [37,38] , the trace nanoparticle reinforced cast 40Cr steel was also prepared by adding nanoparticles into the molten steel based on pre-dispersed nanosized bi-phase TiC-TiB 2 /Al master alloy. The master alloy mainly contains α-Al, spherical TiC particles and prisms or lamellar TiB 2 particles.…”

Surface Modification of Titanium and Titanium Alloys: Technologies, Developments, and Future Interests

“…Since 1950s, Ti, Ti alloys, and even Ti-based composites have become an important type of structural materials, leading to extensive industrial applications in aerospace, marine, chemical engineering, biomedicine, etc. [6,[71][72][73][74][75][76][77][78][79] In aerospace industry, Ti alloys with the properties of high strength, flame retardation, and damage tolerance are commonly used. [76,[80][81][82][83][84] For example, Ti-6Al-4V (in wt%; the same hereafter), which is the first successfully developed Ti alloy, has been widely used for aerospace purposes for its attractive combined performance in strength, plasticity, toughness, and heat resistance.…”

“…Since 1950s, Ti, Ti alloys, and even Ti‐based composites have become an important type of structural materials, leading to extensive industrial applications in aerospace, marine, chemical engineering, biomedicine, etc . In aerospace industry, Ti alloys with the properties of high strength, flame retardation, and damage tolerance are commonly used .…”