Advanced Materials Research Vols. 314-316

Abstract: Adopted the Lagrange quality point coordinate system description method used the FEM analysis software, the reasonable two-dimension heat-mechanic coupling orthogonal cutting model is established in this paper, which uses the ameliorated Coulomb friction theory to simulate the friction status between the chips and tools. This paper simulates the cutting process with different friction coefficient. It can draw conclusions that the cutting forces and the residual stresses of machined surface are increasing with the raising of touching length of rake face and chip, the raising of cutting temperature. The friction coefficient has the important effect on the machining quality.

Abstract: It is found that the tube damage is caused by two induced factors: bubbles erosion as a dispersed phase and chemical composition of water rich in Cl- ions that result in loss of stability of protective oxide layer. The tube is subject to be erosion–corrosion in a given set of conditions, using numerical simulation techniques. The results prove to be erosion–corrosion effects owing to turbulence, bubbles dynamics affect and ensuing erosion rates. In addition, the bulk of Cl- ions which are concentrated at the bend position play a role in that.

Abstract: Tool-work thermo-electromotive force (E.M.F.) is very important signal because it is regarded as the evidence of direct cutting phenomenon at the cutting position.Our aim is to carry out in-process monitoring of tool wear under intermittent cutting conditions. We examined the relation between E.M.F. and tool flank wear to explore the possibility of in-process tool wear detection using E.M.F. Waveform variations in E.M.F. signals corresponding to tool flank wear were observed at the starting position of cut. To determine the cause of these waveform variations, the electric current was also measured and the electric resistance between the tool and work piece were calculated using Ohm's law. It is found that the change in the tool-work electric resistance corresponds to the progression of the tool flank wear.By monitoring this tool-work electric resistance, it is possible to conduct in-process detection of tool flank wear.

Abstract: Tensile tests were carried out on demagnetization 16Mn and Q235 steel samples at loading state, and the magnetic memory characteristics were analyzed. Experimental results show the mean magnetic field intensity (MMFI) of a measuring point is more effective than that of other measuring points at the same stage to study tensile magnetic memory characteristics of demagnetization 16Mn and Q235 steel samples. At the elastic deformation stage, the MMFI of the measuring points at one fracture side increases while it decreases on the other fracture side. The MMFI decreases with the distance from the fracture location, and the change rate of the MMFI is almost equal. The variation law shows changes of opposite direction. At the strengthening phase, the relation between MMFI and tensile displacement is similar with that of the plastic deformation stage, but the variation amplitude was accelerated obviously. Comparison of 16Mn and Q235 steel shows that the standard deviation variation of the magnetic field intensity with the tensile displacement increases as the tensile strength of materials increases. For the demagnetization bearing components, weak areas can be estimated according to breaking laws, so more monitoring points can be set. Pre-breaks could be found through the appearance of inflection point of the MMFI of monitoring point. The inflection point of the mean curve is the breakpoint.

Abstract: Take electrolytic copper powder and SiC powder as the raw materials, apply powder injection moulding to prepare SiCp/Cu composite, while the test result shows that only Cu and SiC exist in the sintered composite, the SiC particles evenly distribute within the Cu substrate. The friction coefficient and the morphology and elemental composition of the worn composite surface are measured in the fiction and wear test. The result shows that the friction coefficient of composite increase in a more gentle pace with the prolonging of the sliding time; the adhesion and plastic deformation of the worn surface of the composite containing 10 vol.% SiCp is light, and there exists certain abrasive wear; while the worn surface of the composite containing 15 vol.% SiCp show obvious abrasive wear, and there exist dense mechanically mixed layer; in addition to the inherent elements of the composite of Cu, Si and C, the worn surface also contains the elements of Fe and O.

Abstract: It has a great tendency to the problem of environmental cracking under the service condition of LPG containing wet H2S surpassing the lowest allowance for steels. In order to quantitatively evaluate the cracking susceptibility on this steel in the wet H2S environment, the pre-fatigue crack M-WOL specimen stress corrosion cracking tests in three H2S concentrations were performed under the different welding conditions, and in safety performance analysis of equipment, and preventing countermeasure had been proposed. The results show that the presence of H2S considerably influences the corrosion process of SPV50Q steel and its corrosion rate increases with increasing H2S contents. With decreasing pH and increasing in temperature of the testing solution, the corrosion of this steel is also enhanced. Although the semicircular diameter of capacitive loop increases with immersion time, its variation amplitude is not obviously great and begins to diminish after certain periodic time, suggesting that the sulfide film formed on the surface can not effectively prevent SPV50Q steel for avoiding the further corrosion.

Abstract: Three-dimensional pattern design of processing draft

Abstract: For the high speed train, safety is the most important factor. Flash welding is the primary technology for the seamless line rail in Chinese railway. So the quality of the flash welded joints is the most important. This paper presents the situation of joint fracture in rail flash welding joints and analyses the failure mechanism through macroscopic and microscopic observation. The result demonstrate that the cracking of the rail is fatigue-crack propagation，the fatigue cracking is caused by alumina calcium-Aluminates-non-metallic inclusion．

Abstract: Deep hole honing is the primary way of finishing, the main problems existing now are the low efficiency, high surface roughness, especially in the processing of difficult to cut materials. In this study, the test is on the titanium alloy and uses the self-developed ultrasonic vibration honing equipment. The results show that in the same conditions, the ultrasonic vibration in deep-hole honing can improve the efficiency about 1 times, and meanwhile the surface roughness can reach below 0.8μm, the oilstone is uneasy to block, and the technical effects are better than traditional honing process.

Abstract: A series of water-based no-clean fluxes composed of an anion/nonion binary surfactant were investigated. The wetting behavior of Sn0.7Cu and Sn3.0Ag0.5Cu on copper with different content of binary surfactant, and the performance of the flux were tested according to the Chinese industry standard of SJ/T 11273-2002 (No-clean liquid Flux). The results showed that the wettability of binary complex was better than that of single surfactant. Two promising fluxes for Sn0.7Cu and Sn3.0Ag0.5Cu solder were selected, respectively. The fluxes showed excellent performance such as halogen-free, less corrosivity, low content of volatile organic compound (less than 5%), high spread rate (over 80%), and high surface insulation resistance (beyond 10⁸Ω). The prepared fluxes meet the requirement of lead-free solder.