Experimental Studies on the Microstructure and Hardness of Laser Transformation Hardening of Low Alloy Steel

Abstract

An experimental investigation with Nd:YAG laser system was carried out to study the effects of laser hardening process parameters on the microstructure and hardness during laser hardening of EN25 steel. The laser beam is allowed to scan on the surface of the work piece by varying the laser beam power (750–1250 W) and travel speed (500–1000 mm/min) of the work table. The microstructural features of the laser hardened EN25 steel were analysed using optical microscope. The microstructure of the surface layer was found to consist of plate martensite. A substantial increase in surface hardness was achieved, by a factor of 2 times the base material hardness.

Multi-Objective Optimization of Turning Parameters Using the Combined Moora and Entropy Method

“…This work piece material has better mechanical strength than carbon steel; hence, it is suitable for die holder, drive shaft, axle, and gear [31]. The selected work pieces are round rod with a 38 mm diameter and turning operations are carried out on 120 mm length in CNC turning centre with coolant conditions.…”

Review on hardfacing as method of improving the service life of critical components subjected to wear in service

“…The welding processes can be grouped as follows: Hardfacing by arc welding -shielded metal arc welding, submerged arc welding; hardfacing by gas welding -oxyacetylene gas welding; hardfacing by combination of arc and gastungsten inert gas welding (TIG), gas metal arc welding; powder spraying -flame spraying, high velocity oxyfuel process, electric arc spraying and plasma transferred arc welding; and laser hardfacing/laser cladding [14]. Some of the welding methods that have been successfully used to apply hardfacings on substrates are: gas tungsten arc welding (GTAW) [28], plasma arc welding (PAW) [29], laser beam welding [30,9], tungsten inert gas welding (TIG), gas welding [31], manual metal arc welding (MMAW) [32], shielded metal arc welding (SMAW) [13,18], and flux cored arc welding (FCAW) [33,34]. Shibe and Chawla [35] summarized the three types of hardfacing deposition techniques as thermal spraying, cladding and welding.…”

“…According to Babu et al [9], the surface hardness of EN25 steel doubled when the laser beam power was varied between 750 -1250W and travel speed between 500 -1000mm/min. Santhosham and Rajendra [42] disclosed that increase in the manganese content with addition of boron in Fe-C-Si-Mn-B electrode resulted in an average hardness of 700VHN when used to hardface low carbon steel of hardness 143VHN.…”

“…It is a pounding type of wear that changes the original dimensions of the part, deforms or splits metal surfaces; crushing hammers and dipper bucket encounter impact in operation [7,8]. Changes in the surface topography of a part due to wear can be regenerated using surface engineering techniques which aim at altering the microstructure and composition of the near surface region of the component without affecting the bulk material in order to achieve the desired surface properties such as abrasion and corrosion resistance, thereby improving its function and useful life [9,10]. Service life of worn components and new parts can be economically extended by a surface engineering technique known as "hardfacing".…”

Optimization of machining parameters in turning operation using combined TOPSIS and AHP method

“…Hence experimental study is required [4]. EN25 steel gives better mechanical property and atmospheric corrosion resistance than conventional carbon steel [5]. Microstructure and hardness of the EN25 steel was analyzed to estimate the effect of process parameters in laser hardening process [6].…”