Dry Sliding wear behaviour of Ferrite-Martensite Dual Phase Steels

In the present investigation, High Strength Low Alloy Steel (HSLA) was subjected to Intermediate Quench (IQ) heat treatment process at four different intercritical temperatures to obtain Dual Phase(DP) steels of varying percentages of ferrite-martensite microstructure The intercritical holding temperatures were 730oC, 750oC, 780oC and 810oC. The corresponding martensite volume fraction obtained were48%,56%,63%and 69%. Specimens for the wear test were prepared as per the ASTM recommended procedures and were tested for the dry sliding wear behaviour at different loading conditions ranging from 19.62N to 49.05N and at constant sliding velocity of 1.257ms-1, on a Pin-on-Disc wear testing machine. The investigation reveals that amount of martensite volume fraction in the dual phase microstructure increases with increase in intercritical temperature and the wear resistance of the Dual Phase steel increases with increase in percentage volume fraction of martensite in the dual phase ferrite-martensite microstructure

Effect of Fatigue Crack Growth Rate on Varied Percentage of Martensite for Welded DP Steel

The objective of this investigation is to study the fatigue behaviour of Dual phase(DP)steel with varying percentage of martensite. The study is conducted on samples of welded Dual phase steel prepared by intercritical annealing process with temperature varying from 7300C to 8100C. In this process both coarse and fine ferrite-martensite structures are produced with volume fraction of martensite varying from 48 to 69%. It has been observed from the investigation that the fatigue crack propagation rates were found to decrease and threshold values of stress intensity factor increase with the increase in martensite content upto 69% for the intercritically annealed structures

Analysis of MEMS Piezoelectric Hydrophone at High Sensitivity for underwater application

Micro-electromechanical systems (MEMS), is a technology that is used to design small integrated devices that combines both electrical (voltage, resistance) and mechanical components (stress, displacement). These devices are assembled using integrated circuit batch processing methods and their size can vary from Micrometers (μm) to Millimeters (mm). MEMS devices have the capability to sense and control the environment. These devices are fabricated using System Integrated chip technology and micro-level segments are manufactured using silicon. To remove the selective parts of silicon i.e. extra silicon parts, Processes such as back etching, high-aspect-ratio micromachining are used to remove selective parts of silicon or to add the extra layers to form the electromechanical components. The study is concerned to design a T- Shape vector Hydrophone using MEMS Technology and to analyses mechanical properties like induced stresses, deformation and to analyses the piezoelectric hydrophone characteristics like frequency response, sensitivity and Voltage to achieve improved sensitivity. MEMS Directional Hydrophone PZT is simulated. Both the structure resembles the fish lateral line and auditory cilia system which converts acoustic pressure into voltage. © 2017 Elsevier Ltd

Evaluation of Electroless Nickel Poly alloys for Drilling of CFRP

Today even though composites have wide range of applications in aerospace and other industries, machining of composites is still considered to be a difficult task. In this study, efforts are made to reduce drill bit wear characteristics during machining of CFRP composite. Electroless coating method is used to coat nano-crystalline ternary Ni-W-P coating on HSS drill bits of diameter 7mm, to carry out drilling operations on CFRP. The coatings are characterised by their morphology, composition, structure, phase transformation behaviour and nano-hardness. By subsequent pre-treatment steps, Ni-W-P coatings are adhered on HSS drill bits and coarse nodular structures were observed upon surface testing by using FESEM. About 14.5 weight of W, 5.41 weight of P with balance of Ni was observed in the compositional analysis of the deposit carried out by EDAX. With constant feed and speed, drilling operation carried out on CFRP plate of thickness 2.5 mm and drill bit characteristics were evaluated. HSS drill bits of type uncoated, Ni-W-P coated and heat treated were used for drilling CFRP plate. Drill bits tool wear were examined by using Tool Makers Microscope. The drilling operation is carried out to drill 100 holes on CFRP plate by all types of drill bits and the drill bits were examined at every 20 intervals of drilling. It was found that Ni-W-P coated drill bits have shown about 60 reduction (0.2mm less) in chisel edge wear, about 40 (0.1mm) lower wear on cutting edge and about 60 (0.5mm) less wear on flank surface compared to uncoated and heat treated drill bits. Based on the results obtained in this study, electroless ternary Ni-W-P coating seems to be most likely material which enhances the tool life and gives better quality machining. Selection and Peer-review under responsibility of Advanced Materials, Manufacturing, Management and Thermal Science (AMMMT 2016)

Investigations on the Effect of Ball Burnishing Parameters on Surface Roughness and Corrosion Resistance of Hsla Dual - Phase Steels

Surface finish has a vital influence on most functional properties of a component, such as fatigue strength, wear resistance and corrosion resistance. This has led to processes such as lapping, honing, and burnishing. Burnishing is a fine finishing operation involving the cold working and plastic deformation of surface layers to enhance the surface integrity and the functional utility of a component. This study has been carried out to establish the effect of burnishing parameters, i.e. feed rate, speed, force, ball diameter and lubricant on surface roughness and corrosion resistance of HSLA dual – phase steel specimens. The result indicates that burnishing parameters have a significant effect on surface roughness and corrosion resistance