Advanced Materials Research Vols. 931-932

Abstract: The TIG pulse welding of 15Cr-4Ni-8Mn-1.3Cu austenitic stainless steel at pulse currents of 130 and 160 A with Argon shielding gases containing 0%, 5% and 10% (v/v) Nitrogen was investigated. The effects of pulse current and Nitrogen content in Argon shielding gas on the microstructure and mechanical properties of weld metal were studied. Based on the results found in this study, the nitrogen content in weld metal was found to increase with increasing nitrogen content in argon shielding gas and pulse current. With the addition of nitrogen in Argon shielding gas, the morphology of delta-ferrites was changed from the conventional TIG pulse welding using pure Argon shielding gas where both lathy and vermicular types were found. However, with the Nitrogen + Argon shielding gas, only vermicular type was observed. Moreover, the arm spacing of delta-ferrite can be enlarged by increasing the pulse current. Those results are the reason for the observed decrease in tensile strength and percent elongation with increasing nitrogen content in argon shielding gas and the pulse current.

Abstract: Copper containing aluminium alloy AA6110 is introduced to automotive industries for the last few decades. An understanding of its precipitation sequence and mechanical properties during ageing treatment is valuable to optimize some heat treatment processes in the automotive manufacturing. Therefore, in this study, the precipitation sequence, microstructures and mechanical properties of copper containing aluminium alloy AA611 were investigated. A differential scanning calorimeter (DSC) with regular heating rate of 10 °C/min was performed on the solid solution heat treated aluminium alloy AA6110 for the precipitation sequence investigation. Solid solution heat treated samples were aged at different temperatures and times. Hardness values of differently aged aluminium alloy AA6110 were measured to determine optimized parameters of the ageing process. It was found that the maximum hardness value of 141 HV was detected at an ageing temperature of 160 °C for about 12 hr. Tensile properties and microstructures using transmission electron microscope (TEM) of specimens aged at a temperature of 160 °C with different ageing time will be investigated and shown.

Abstract: Optical strain analysis system plays an important role in tools and dies design, particularly in the phase of die design and die tryout. The objective of this paper is to present the information of the application by using the optical strain measurement device in tools and dies design and material testing. Therefore, two cases in mechanical testing and one case of tools and dies design are demonstrated. The AutoGrid^® Compact strain measuring device is applied for all cases. The determination of Forming Limit Diagram (FLD) by using tensile testing machine and U-bending test supported by the optical strain measuring technique is performed and illustrated. In this paper, the procedure of material testing is developed and applied from related literatures. The result obtained from several cases shows the powerful performance of using the strain measurement device for providing the strain information in each situation of forming material as required so that the engineer can tackle the problem and find the solution to improve the production processes in a short time.

Abstract: Al-Zn-Sn anode is not popular for corrosion prevention in marine environment as much as Al-Zn-In anode and Al-Zn-Hg anode because it requires proper heat treatment to obtain the optimum anode capacity. This paper investigates what factors would influence the anode performance of Al-Zn-Sn anode. The fine and homogeneous microstructure is the factor that plays important role to improve the anode capacity. The manufacturing techniques producing fine and homogeneous microstructure in aluminium alloys might be helpful to increase the performance of the anode without the heat treatment process.

Abstract: The objective of this research is to study comparisons of Cu and CuZn electrodes, during Electrical Discharge Machining (EDM) of martensitic stainless AISI 410. The workpiece material was a rectangular plate, measuring 30x50x5 mm. The conditions of the EDM process were 3.0mm depth and 2.0 mm diameter, with variables of parameter being: currents, on/off-times and open circuit voltages of spark. Evaluation of the electrical discharge was conducted using Material Removal Rate (MRR), Electrode Wear Ratios (EWR) and Arithmetical Mean Roughness (Ra), respectively. The results found that CuZn electrode materials provide higher MRR and EWR than electrode materials of Cu. Also, when considering the melting of white layer, initial melts found that the white layer surface material is also good for the integrity of the state park, and it was additionally also found that when the current level increases, then that will rise accordingly.

Abstract: The objective of this research is to study and compare quality milling surfaces, and the effects of plastic mould steels AISI-1050 and AISI-P20, in a milling process with various parameters based on experimental conditions, such as: 1) feed rates at 45, 50 and 55 mm/min, 2) spindle speeds of 510, 572 and 637 rpm, and 3) milling levels at 3, 5, and 10 mm, respectively, using a 10 mm twin flute ended type mill. The experimental results found that plastic mould steels which had the best quality milling surface were AISI-P20 and AISI-1050, with roughnesses of 2.627 μm and 2.120 μm, respectively. Quality milling surfaces were milled by using the most suitable parameter feed rate of 45 mm/min, a spindle speed of 637 rpm and a cut depth level of 3 mm, for both tested grades. However, characteristics of milling surfaces and wear of the mill end were directly influenced by changes of parameters for all test conditions. As a result, the quality of milling surfaces also changed.

Abstract: This work studied the effect of Nickel addition to improve the oxidation behavior of austenitic stainless steels at 1,073 K and 1,173 K. The results show that Nickel increases the oxidation resistance of the austenitic stainless steels. The compositions of oxide scale also change form only Cr₂O₃ to be Cr₂O₃, Fe₂O₃, NiFe₂O₄ and Ni (Cr₂O₄). The oxidation behavior follows the parabolic rate law; W = ktⁿ, where W = weight gain (g/cm²), t = time (s), k is the exponential rate constant and n is the exponent of growth rate. The n values are between 0.47-0.88.

Abstract: The objective of this research was to investigate the effect of parameters on the microstructure and mechanical properties of friction stir welded butt joints of dissimilar aluminum alloy sheets between Semi-Solid Metal (SSM) 356 and 7075. The base metal of SSM 356 and 7075 was located on the advancing side and the retreating side, respectively. The cylindrical pin was used as the welding tool geometry. Friction stir welded using different tool rotation speed (710, 1000 and 1400 rpm) and welding speed (80, 112 and 160 mm/min). The result indicated that the maximum average tensile strength of 205.13 MPa was achieved for the joint produced at tool rotation speed 1000 rpm, welding speed 160 mm/min. In addition, the metallurgy and welding structures of combined two types aluminium showed more definite than the base metal.

Abstract: The aim of this study was to investigate the effects of important factors in microimprinting, which could be used to create the anti-bacterial pattern on stainless steel sheets. The microimprinting process was modeled and simulated by using finite element analysis (FEA). The following factors were considered: forming steps, forming velocity, grain size, and friction coefficient. The simulation results showed that two-step forming helped reduce peak errors. Increasing forming velocity and friction coefficient tended to increase peak errors. The grain size effect was not noticeable because the selected grain sizes were much larger than that of the micro feature.

Abstract: The purpose of this research was to investigate the effect of the main factors on the surface roughness in mold steels face milling by carbide tool for results obtained from the analysis used in the manufacture of molds and other parts of the industry. The etching experiment using semi-automated milling machine Obraeci Strojie brand FGV 32 model. Concerning the material was steel grade AISI P20 mold with a hardness between 280-325 HB which used to insert carbide tool. The factors of a speed, feed rate and depth of cut were study. Preliminary experiments showed that the depth does not affect the surface roughness fix depth of cut at 0.5 mm. The experimental revealed that the factor affecting surface roughness was feed rate and speed. The roughness value trenced to reduce at lower feed rate and greater speed. It was possible determine a facing condition by means of the equation Ra = 1.29 - 0.000654Speed + 0.00305Feed rate leading this equation goes to use is in limitation speed 500-1,000 rpm. at feed rate 160-315 mm/min. From the experiment was confirming the result of a comparison between the equation and the percent accuracy with the margin of error. The result from the experiment of mean absolute percentage error (MAPE) of the equation of surface roughness was 3.27% which was less than the margin of error and was acceptable. The pattern of wear was similar to mechanical fatigue cracking. It may be due to the verious tip of the cutting tool or an impact and flank wear as cutting tool materials resistant to wear less.