316L Stainless Steel Composites Research Articles

Additive manufacturing of graphene reinforced 316L stainless steel composites with tailored microstructure and mechanical properties

Since its inception, additive manufacturing has facilitated the processing of novel metal matrix composites that are challenging to fabricate using conventional manufacturing methods. The laser-based additive manufacturing process is a promising technology to fabricate uniformly dispersed graphene-reinforced stainless steel nanocomposite. In this study, the effect of energy density modulation on densification, microstructure, and mechanical properties of (316L) stainless steel reinforced with 0.2 wt% multi-layered graphene nanosheets was investigated. The highest relative densification (94.7% ± 0.5) has been achieved at the volumetric energy density of 240 J/mm3. The formation of dislocation cells, inclusions and graphene-steel interaction have been identified in the microscopic analysis. Addition of graphene as reinforcement and nano-inclusions formed (in situ) during solidification promotes the pinning of dislocations around the cellular sub-grains. Alteration of volumetric energy density is an essential technique to tune the texture and microstructure of the additively manufactured samples. As the volumetric energy density increased to 240 J/mm3, the tensile strength achieved is around 1165 ± 5 MPa.

Microstructure and Nanoindentation Behavior of FeCoNiAlTi High-Entropy Alloy-Reinforced 316L Stainless Steel Composite Fabricated by Selective Laser Melting.

Selective laser melting (SLM) is one of the metal additive manufactured technologies with the highest forming precision, which prepares metal components through melting powders layer by layer with a high-energy laser beam. The 316L stainless steel is widely used due to its excellent formability and corrosion resistance. However, its low hardness limits its further application. Therefore, researchers are committed to improving the hardness of stainless steel by adding reinforcement to stainless steel matrix to fabricate composites. Traditional reinforcement comprises rigid ceramic particles, such as carbides and oxides, while the research on high entropy alloys as reinforcement is limited. In this study, characterisation by appropriate methods, inductively coupled plasma, microscopy and nanointendation assay, showed that we successfully prepared the FeCoNiAlTi high entropy alloy (HEA)-reinforced 316L stainless steel composites using SLM. When the reinforcement ratio is 2 wt.%, the composite samples show higher density. The SLM-fabricated 316L stainless steel displays columnar grains and it varies to equiaxed grains in composites reinforced with 2 wt.% FeCoNiAlTi HEA. The grain size decreases drastically, and the percentage of the low angle grain boundary in the composite is much higher than in the 316L stainless steel matrix. The nanohardness of the composite reinforced with 2 wt.% FeCoNiAlTi HEA is twice as high as the 316L stainless steel matrix. This work demonstrates the feasibility of using a high-entropy alloy as potential reinforcement in stainless steel systems.

Carbon nanotube (CNT) reinforced 316L stainless steel composites made by laser powder bed fusion: Microstructure and wear response

Carbon nanotube (CNT) reinforced 316L stainless steel (SS) composites were fabricated by laser powder bed fusion (LPBF) additive manufacturing (AM). This study focuses on microstructure evolution, hardness, and wear behavior. The wear behavior for AM 316L SS and 1 wt% CNT/316L SS was studied by a dry sliding test under normal loads of 10, 15, and 25 N. The addition of CNT to 316L SS led to the change of solidification mode from cellular/columnar to dendritic growth, producing grain refinement. Nanoscale dendrites were observed. Although TEM characterization confirmed the existence of CNT in cell interior, most CNT were damaged, resulting in carbon material segregation along cellular/dendritic boundaries. The wear rate was found dramatically decreased due to the improved hardness. Compared to the adhesive and abrasive wear in AM 316L SS, the wear mechanism of CNT/316L composite was adhesion and oxidative wear. Enhanced cellular/dendritic boundary strengthening by carbon segregation was the main strengthening mechanism of CNT/316L composite.

Laser cladding of TiC reinforced 316L stainless steel composites: Feedstock powder preparation and microstructural evaluation

Laser cladding was used to fabricate 316L/TiC composite coatings after optimizing the feedstock powder morphology. Firstly, the influences of ball-to-powder ratio (BPR) and milling duration on the morphology were investigated. The BPR of 1: 1 and 2 h of milling was sufficient to attach considerable amount of TiC particles onto 316L particles. Then, the microstructure and hardness behaviors of 15 vol% TiC reinforced 316L coatings were examined. Partial or total dissolution of the original TiC powders led to the formation of a reinforced austenitic microstructure with a hardness increase of 100 HV. This increase is due to a grain refinement effect of the TiC during solidification and the presence of new solidification carbides. Partially dissolved and primary MC globular carbides are well-distributed in the matrix together with few larger MC globular carbides. Furthermore, MC coral-like pseudo-primary carbides and MC branched eutectic carbides are observed inside the cells and in intercellular spaces, respectively.

Microstructure and Mechanical Properties of TiC-Reinforced 316L Stainless Steel Composites Fabricated Using Selective Laser Melting

TiC/316L stainless steel (316Lss) metal matrix composite parts have been formed using selective laser melting (SLM). In this study, we have investigated the influence of the TiC mass fraction on the microstructure evolution, microhardness, friction properties, wear properties, and corrosion resistance of the TiC/316Lss composites. The results show that the microhardness increased by the addition of the TiC mass fraction. In terms of friction and wear properties, the corrosion resistance initially increased, and then decreased. Compared with the pure 316Lss (298.3 HV0.2), the microhardness of the TiC/316Lss composites, which were formed with 2 wt% TiC, was raised to 335.2 HV0.2, which was a 12.4% increase, while the average friction coefficient was 0.123. The reason for this is that the addition of TiC can effectively refine the cell size, and as the TiC content increases, the refinement effect is more obvious. During the melting process, TiC particles act as nucleation centres, hindering the growth of crystal cells, promoting the formation of the austenite phase, and forming fine equiaxed structures, which increases the strength. However, excessive TiC particles aggravate the spheroidisation during the process of SLM, leading to increased defects, as well as a decrease in density and corrosion resistance.

Tribological Properties of Steel/Tib2 Composites Prepared by Spark Plasma Sintering/ Własności Tribologiczne Kompozytów Stal/Tib2 Otrzymywanych Metodą Sps

Abstract mechanical and tribological properties of sintered 316L stainless steel composites with TiB2 submicroparticles were investigated. The composites were manufactured by Spark Plasma Sintering (SPS). The wear behaviour was studied by using a ball-on-disc wear tester at room temperature. The worn surface were analysed using Scanning Electron Microscopy (SEM). The results indicated that the friction coefficient and the wear resistance of composites with the same content of TiB2 particles depend on the sintering conditions.

Corrosion behavior of HA-316L SS biocomposites in aqueous solutions

316L stainless steel and Hydroxyapatite (5, 20 and 50 wt. (%) HA)-316L stainless steel composites were fabricated by mechanical alloying technique, pressing and sintering from 316L and HA powders. The corrosion behavior of both sintered 316L and HA-316L composites was evaluated by electrochemical techniques in simulated body fluid (Ringer's solution) and in 0.1M HCl solution which simulates occluded cell corrosion conditions. The results indicate that 316L stainless steel and HA-316L composites are passive in Ringer's solution and active in HCl solution. All materials are highly corrosion resistant in Ringer's solution with corrosion current density in the order of 10-6 A cm-2 or less. Both 316L stainless steel and 5% HA-316L composite present good corrosion resistance in HCl with corrosion current density in the order of 10-5 A cm-2. The corrosion resistance decreases with increasing HA content in both solutions.

Preparation and Properties of Cu-10Sn Alloy Infiltrated 316L Stainless Steel Composites

A new method to produce powder metallurgy (P/M) 316L stainless steel matrix composite by pressureless infiltrating Cu-10Sn alloy was studied. The effect of various compaction pressures and infiltrating temperatures on the microstructure, mechanical properties and corrosion resistance was investigated. The results show that high density P/M 316L stainless steel matrix composite could be achieved by infiltration. A maximum relative density of 98% was achieved, provided that the porosity of the skeleton was controlled at 18%~22%. After infiltration, hardness of the samples increased from 49 HRB to 89 HRB. Moreover, the critical corrosion potential reached -212 mV, close to the level of as cast 316L stainless steel. The hardness of infiltrated composite of the same density decreased with increase in initial skeleton density. It was necessary to prevent the egregious grain growth while the infiltrating temperature was too high.

Effect of TiC Addition and Cooling Rate on Mechanical Properties of 316L Stainless Steel Composites

The present research work concerns the development of TiC reinforced 316L stainless steel composites through powder metallurgical technology and sintered in vacuum. The effect of TiC particle addition and cooling rate on the mechanical properties of 316L stainless steel composites has been investigated. The results show that increasing the cooling rate caused enhancement of ultimate tensile strength and microhardness. However, the elongation to failure of the composites was decreased with the increase of cooling rate. The addition of TiC particle was found to improve the ultimate tensile strength of 316L stainless steel composites. The highest tensile strength was 648 MPa in specimens containing 5wt.% TiC. Further increase in TiC content to 10wt% results in a reduction in tensile strength to 631 MPa.

Microstructure and abrasive behaviors of TiC-316L composites prepared by warm compaction and microwave sintering

316L stainless steel composites with various weight fractions of TiC particles were prepared using warm compaction and microwave sintering. Abrasion resistance measurements were used to study the abrasive behaviors of TiC-316L stainless steel composites. The effects of TiC content and preparation methods on the microstructure and mechanical properties of 316L stainless steel composites have been investigated. The results showed that the sample prepared by warm compaction and microwave sintering exhibited significantly superior densification, higher hardness, and better abrasion resistance when compared with conventionally processed counterpart. TiC particles reinforcement improved the abrasion resistance of 316L stainless steel, and the abrasion resistance of the composites was considerably better than that of the 316L stainless steel. The volume loss initially decreases with increasing TiC content up to 5wt.%, it then slightly increases as increase the TiC particles content to 10 and 15wt.%. In this present abrasion tests, the composites using 5wt.% TiC addition offers a high abrasion resistance.

The mechanical behaviour of interpenetrating phase composites — III: resin-impregnated porous stainless steel

Powder metallurgy (P/M) derived porous metals that have been impregnated with a polymer resin to create fully dense composites are examples of interpenetrating phase composites (IPCs), in which each phase forms a completely interconnected network. In this paper, we describe an experimental and modelling investigation of the mechanical properties of resin-impregnated P/M derived porous 316L stainless steel composites of various volume fractions, with a view to gaining a better understanding of the mechanical properties of IPCs. In comparison with a similar investigation of 420 stainless/bronze IPCs, properties of the 316L stainless/resin IPCs are less well represented by non-linear finite element analysis based on a unit cell model with periodic boundary conditions. This is attributed to the more irregular microstructure of the 316L/resin IPCs, greater uncertainty in the properties of the constituent materials, and larger differences between constituent properties. Considering only mechanical properties, the 316L stainless/resin combination does not appear to take advantage of the interpenetrating phase morphology, since the resin does not possess a superior property to contribute to the composite as a whole.