Advanced Materials Research Vols. 712-715

Abstract: The introduction and application of common finite element method (FEM) about the modern metal cutting theory research was stated emphatically. Graded self-lubricating ceramic tool materials was briefly introduced, and problems existed about simulating the metal cutting process using FEM are pointed out and discussed in this study.

Abstract: Some gas fields with high hydrogen sulfide content, such as Luojiazhai, Dukouhe and Puguang Gas Fields, are found in Northeast Sichuan. For exploring and utilizing high sulfur natural gas reservoirs, it is essential to quantificational analysis of sulfur compounds and elemental sulfur in high sulfur natural gas. Determination of hydrogen sulfide content in natural gas with a laser method has many advantages, including on-site measurement, fast response, wide application scope, high accuracy, high reliability, and low maintenance. When the hydrogen sulfide concentration is 1% to 20%, the relative deviation of the analysis value to the standard value is less than 3% with repeatability of less than 1%. Determination of sulfur compounds in natural gas by gas chromatograph with sulfur chemiluminescence detector (SCD) also has many advantages, such as it is simple, fast, accurate and free from interference of most sample matrixes. The analysis method has good repeatability with lower limit of detection. Since SCD has liner equimolar response to sulfur atom, only one reference gas mixture of sulfur compound is used as external standard calibration. Determination of total sulfur content in natural gas with oxidative microcoulometry method has good repeatability and high accuracy. Determination of elemental sulfur by liquid chromatography has repeatability better than 3%, the detection limit is 10mg/m³, and recovery rate of over 90%, and is applicable for determination of elemental sulfur content in high sulfur natural gas.

Abstract: A novel two-step heating process, consisting of a short-time high temperature heating followed by isothermal solidification at a lower temperature, was used to transient liquid phase (TLP) bond T91 steel. The interface morphology of the joint was investigated and compared with that of conventional TLP bond made at a constant bonding temperature. The results show that the two-step heating process produces a non-planar interface at the initial stage, which is different from the planar interfaces associated with conventional heating process. No interface can be found in the final joint by two-step heating process, however, a planar interface still exists in the final conventional TLP bond. Therefore, the bending ductility of the joint is dramatically improves by the two-step heating process, and the joint properties are similar to that of base metal.

Abstract: The microstructure revolution of a spur gear shaft during hot forging was numerically simulated with FEM using Yada Model. The grain size distribution of the gear shaft after hot forged using initial billets with different dimensions was obtained through microstructure simulation and relative metallographic experiment show a good agreement with the simulation result. Effect laws of different forging parameters including the initial forging temperature and the punch speed, on grain size of the gear shaft after forged were given. A preforming process was proposed and the microstructure simulation shows that the preforming process can significantly improve the grain size refinement and distribution uniformity of the gear shaft by hot forging.

Abstract: This paper presents the development and design of the laser cladding machine for marine diesel engine crankshaft in-situ repairs. The described technology and device is designed to perform crankpin journal build-up operations directly in the engine housing, without removing the crankshaft from the engine. Furthermore, this technology could be successful-ly combined with the subsequent final machining operation grinding. There is already equipment and technology in place for in-situ crankpin grinding operations. Both technological platforms can be combined to deliver the most appropriate output. For the very first time, this paper outlines the novel, in-situ concept of applying laser cladding to marine crankshafts. The principal design of the in-situ laser clad-ding machine is provided and is accompanied with a de-tailed description of the in-situ laser cladding machine construction. The proposed device and method satisfy ship-board crankshaft surface renovation needs and opens up an entirely new dimension for the industrial application of laser cladding technologies.

Abstract: To obtain fine-grained products of ultra-deep drawing hot rolled steel sheets,effect of deformation,deformation temperature,deformation rate on microstructure refinement were investigated through multi-pass hot-rolling finish-rolling process test.Experimental results show that gain size decreased with the increase of total deformation and the first-pass deformation in a certain finish rolling temperature range.Gain size decreased with the decrease of deformation temperature and the increase of deformation rate.Through the industrial test rolling,grain size of hot rolled steel sheets was up to 8.5.

Abstract: In order to provide references for the application of low frequency torsional vibration tapping, three typical difficult to cut materials 30CrMnSi, GH4169 and TC4 were selected to carry out experiments. Experiment results show that net cutting angle L_T and backoff angle L_G have great influence on tapping torque, and the process parameters should be selected reasonably according to material characteristics and combining with tapping efficiency. Larger L_G and smaller L_T should be selected for materials with small elastic modulus such as TC4. Smaller L_G and larger L_T can be selected for materials similar to 30CrMnSi. For materials similar to GH4169, parameters should be selected between that of TC4 and 30CrMnSi.

Abstract: Strip shape defects, especially the crown problem, once appeared in the production of hot-rolled strip steel in SG Company. The macroscopic characteristic is the thickness difference occurred between the center and edge cross section of hot-rolled plate. Morphological characteristics and forming reasons can be got by analyzing roll wear. Research shows that the main reason for the formation of crown is excessive attrition of work roll in later period, which leading to smaller roll shape. Therefore, shape defects have been effectively controlled after introducing CVC roll contour technology to optimize roll shape. Quality qualified rate of strip shape of hot-rolled strip steel is more than 99.6% percent, and it has been successfully put into application of hot rolling mill.

Abstract: To solve vacuum casting process exist two-component polyurethane difficult to uniform mixing problems. A non-symmetric eccentric large blade agitator was proposed and the speed was period changed to strengthen the mixed effects. A fluid dynamics of variable speed agitator tank was proposed to numerical simulation flow behacior with Euler - Euler two-fluid model and the dynamic mesh (SM) method. Though numerical simulate to study flow field characteristics of variable speed agitator tank.. The experiment results show that the proposed method can not only achieve high viscosity polyurethane resin with uniform mixing, and shorten the processing time. Effectively solve the polyurethane resin materials difficult to uniform mixing problems.

Abstract: Most bast fibers and leaf fibers are harsh ,stiff and of high initial modulus, so the fabric made of them are prickling and difficult to go out of shape. The prickle and local stress of the fabric which are made of the blend of hemp, viscose and micro-porous polyester fiber were tested here, and the effect of the structure of the fabric on the prickle and local stress were analysed. It can be seen from the test result that the hemp content was not the most important factor to the prickle, warp and weft shrinkage and fabric count influence the prickle the most. As far as the local stress is concerned, he fabric pattern influence the stress transmission within the fabric obviously.