Experimental research on electromagnetic continuous casting high-speed steel composite roll

A high speed steel composite roll billet was fabricated, which is regular in shape, smooth in surface, slight in trace, compact in internal structure, free of slag inclusion, shrinkage cavity, cracks and other flaws, and good in macro quality of junction surface using a vertical continuous casting machine. The interface zone microstructure of bimetallic in billet of high speed steel composite roll was analyzed by metallurgical microscope(OM), X-ray diffractmeter(XRD), scanning electron microscopy(SEM) and energy-dispersive X-ray analysis(EDS). The results indicate that the microstructure of roll billet is composed of chilled solidified layer, dendrite zone, interfacial zone of bimetal and core material zone. The microstructure of outer shell material is composed of martensite + bainite + residual austenite + some small labyrinth-shape, small-short lath-shape, or dollop-shape eutectic carbides. The microstructure of core material is slice-shape pearlite and a little ferrite along boundary of cells. The interface region microstructure of bimetallic composite roll consists of diffusion region, chilled solidified layer and columnar grain region.

Modeling of the Shape Forming of Composite Roll

A shape modeling of spray formed composite roll, which is utilized to predict the shape and dimension of roll during spray forming process, is developed in this paper. The influences of the principal spray forming parameters, such as the spatial distribution of melt mass flux, spray distance, rotating and translating speeds of substrate bar etc. , on the geometry and dimension of spray formed product were investigated.

Rolling of Al-SiC_p Composites

Aluminum based metal matrix composites are offering o utstanding properties in a number of automotive and aircraft components and body structures. The major advantages of these composite materials are their high st rength to weight ratio, high stiffness, high hardness, wear resistance, low coef ficient of thermal expansion, superior dimensional stability and versatility to designer. In addition to these their isotropic properties, good forming characte ristics, easy availability of cheaper reinforcements along with the availability of comparatively low cost, high volume production methods have made them a prom ising material for future growth. Weight reduction is a major goal of automotive innovations. Lighter vehicles/ ai rcraft means less fuel consumption, reduced emissions, and improved performance. Components made from highly loaded aluminium matrix composites are attractive r elative to iron based materials because of their low density, high stiffness (eq uivalent to nodular iron) and better heat transfer characteristics. The basic co st of materials is higher with these advanced composites; however, manufacturing the part to near net shape may offset basic material costs. A good aluminium based material design can improves safety. The aluminium-based composites can give cars better acceleration and braking, improved handling, ex cellent durability, and ease of repair. Tha aluminum-based composite performs a s well or better in crash than conventional steel-structured cars because of th eir larger volume, which can absorb more crash energy. Another excellent advanta ge of Al-SiC p composite in auto design is better stability and response, and reduced noise, vibration/harshness (NHV). These advantages stem from reduced veh icle weight combined with high structural stiffness and also lead to improved st ability and turning response. In the present work Al-SiC p composite plates of 10 to 12 mm thickness w ere cast using sand casting as well as die casting process. The plates were furt her machined to 3 to 4 mm thicknesses. The machined plates were subjected to col d as well hot rolling. The cold rolling of Al-3 wt.% SiC composite plates was done on 2 high experimental cold rolling mill at Indian Oil Corporation Ltd., R esearch and Development centre, Faridabad. For hot rolling, the Al-5 weight % SiC p composite plates were heat treated at 500 ℃ temperature and Al-15 weight % SiC p composite plates were heat treate d at 550 ℃ temperature for 20 minutes. The plates were hot rolled on 2 high ro lling mill of one ton capacity at IIT Delhi. The maximum percentage reduction ob tained after hot rolling of Al-5 weight % SiC p composite and Al- 15 weight % SiC p composite plates for 10 passes was 11 % and 6 % respectively. During col d rolling of Al-SiC p composites cracks (particle fracture) were observed due to the low ductility of Al-SiC p composties at room temperature. The various m echanical properties such as tensile strength, hardness and wear resistance were measured for the rolled and un-rolled Al-SiC p composite plates. The tensile strength of un-rolled and rolled Al-5wt.% SiC p composites are shown in Tab. 1. Table shows that the tensile strength decreases after rolling. This may be du e to the damage of the bonding between aluminum and silicon carbide particulates . The Rockwell hardness values of Al-5 wt.% SiC p composites measured before a nd after hot rolling are shown in Tab.2. The hardness was found to decrease afte r hot rolling, which may be due to the annealing of composites during heating. T he Rockwell hardness values of Al-3 wt.% SiC p composites before and after cold rolling are shown in Tab.3. The Table shows that the Rockwell hardness of Al-SiC p compostes increases after cold rolling due to the workhardening effec t. The wear resistance of rolled and un-rolled Al-SiC p composites were teste d on reciprocating ball on flat wear testing machine. The wear resistance of Al -SiC p composites decreases after hot rolling due to decrease in hardness

Modeling of Heat Transfer and Solidification of Composite Roll

Modeling of heat transfer and solidification of composite roll was established and used to predict the thermal history and solidification process of roll during spray forming. Evolution of temperature field of the preform and cooling rate in the growing deposit during spray deposition and post-deposition were numerically simulated.

The finite element analysis of articular cartilage fiber-reinforced composite model under rolling load

Articular cartilage is a layer of low-friction,load-bearing soft hydrated tissue covering bone-ends in diarthrosis,which plays an important role in spreading the load,reducing the joint contact stress,joint friction and wear during exercise.The vital mechanical function

GNPs/Al nanocomposites with high strength and ductility and electrical conductivity fabricated by accumulative roll-compositing

Aluminum matrix composites(AMCs) reinforced with graphene nanoplatelets(GNPs) were fabricated by using an accumulative roll-compositing(ARC) process.Microstructure, mechanical and electrical properties of the nanostructured AMCs were characterized. The results showed that small addition(0.2 vol% and 0.5 vol%) of GNPs can lead to a simultaneous increase in the tensile strength and ductility of the GNPs/Al nanocomposites, as compared with the same processed pure Al. With increasing GNPs content, the tensile strength of the GNPs/Al nanocomposites can be enhanced to 387 MPa with retained elongation of 15%. Meanwhile, the GNPs/Al nanocomposites exhibited a good electrical conductivity of77.8%–86.1% that of annealed pure Al. The excellent properties(high strength, high ductility and high conductivity) of the GNPs/Al are associated with the particular ARC process, which facilitates the uniform dispersion of GNPs in the matrix and formation of ultrafine-grained Al matrix. The strengthening and toughening of the GNPs/Al nanocomposites were discussed considering different mechanisms and the unique effect of GNPs.

Influence of hot rolling on microstructure and mechanical characteristics of explosive-welded FSS/CS laminate

The influence of hot rolling on the microstructure and subsequent mechanical characteristics of explosive-welded ferritic stainless steel （FSS）/carbon steel （CS） laminate was investigated. The results indicate that by hot rolling, decarburization layer disappears and a uniform structure is gained in CS side, but ferrite grains and carbides in constituent FSS form an uneven band microstructure which is denser at superficial zone than near the interface. The transmission electron microscopy results indicate that the layers adhering to the interface show typical deformed microstructure features, i.e., stream-like strips and elongated grains in FSS plates, carbide precipitates and bended cementite fragments in CS plates; and high-density dislocations in both plates, With hot rolling, various mechanical strengths and hardness are increased, while the elongation percentage is diminished. Examination of fractographs from tensile tests reveals predominately small dimples for explosive-welded specimens, whereas both big dimples and cleavage fracture for rolled specimens. Stereomicroscopic fractographs taken on shear samples indicate that the surfaces of explosive-welded specimens exhibit uniform deformation, but uneven deformation is displayed for that of rolled specimens. These results indicate that hot rolling is beneficial to improve the strength of explosive-welded FSS/CS laminate but not good for enhancing its plasticity.