Structure–property correlation in laser surface treated AISI H13 tool steel for improved mechanical properties

Heat treatment and surface processing are critical aspects of design and manufacture of components in a wide range of industrial sectors. Engineering materials, such as steel, are heat treated under controlled heating and cooling to alter their chemical, physical and mechanical properties to meet desired engineering applications. Gears engaged rotating at several thousand RPM. Inner Barrels of Injection Moulding machines, which is subjected to wear when thermoplastics, glass fibres are chosen to be injection moulded, Guide pillar Guide bush which slide over each other needs to be hardened from outside to improve hardness and wear resistance, but ductile from inside to bear fluctuating load, for this types of operation Case Hardening is required, to give desired property. In this detailed and systematic investigation, we have selected AISI H13 tool steel as for our research work specimen and we have made an effort to find out the mechanical properties (EDX, Hardness HV, Pin on Disc wear test) and micro structural properties (SEM, XRD) by comparing the two process one is traditional Case hardening heat treatment process i.e. Gas Nitriding and a new process i.e. Coating of Ni-based alloy powder on H13 Tool steel by Microwave Hybrid Heating (MHH) method in household microwave oven at 900W and 2.45 GHz and further find the best process. Investigation shows that coated Sample has good Wear resistance as compared to unmodified H13 Tool Steel sample and nitrided sample, Vicker’s micro-hardness of nitride sample is found to be 829.5HV, and for coated sample is 788HV, Coated sample has good Microstructure as compared to nitrided sample and is free from porous cracks.

Download Full-text

Investigation of Thermal Cycle and Hardness Distribution in the Laser Cladding of AISI H13 Tool Steel Produced by a High Power Direct Diode Laser

Volume 2A: Advanced Manufacturing ◽

10.1115/imece2013-62193 ◽

2013 ◽

Cited By ~ 4

Author(s):

Parisa Farahmand ◽

Prabu Balu ◽

Fanrong Kong ◽

Radovan Kovacevic

Keyword(s):

Mechanical Properties ◽

Phase Transformations ◽

Diode Laser ◽

Laser Cladding ◽

Tool Steel ◽

Thermal Cycle ◽

Thermal Cycles ◽

H13 Tool Steel ◽

Aisi H13 ◽

Aisi H13 Tool Steel

Laser cladding (LC) of tool steel has significant application in rapid tooling, and surface coating for worn-out components in different industries. During the LC process, several phase transformations influence the microstructural and mechanical properties of the deposited layer. In order to successfully implement the LC process, it is essential to understand the relationship between the thermal cycle (heating and cooling), phase transformations, and the output quantities of the deposited layer. In this study a direct diode laser with a power of up to 8 kW was used to deposit AISI H13 tool steel on mild steel grade A36 substrate to enhance its surface properties. Primarily, an experimentally verified three-dimensional (3-D) heat transfer analysis was developed based on the finite element method to compute temperature history during the cladding and cooling process. Next, the computed thermal cycles were coupled with a semi-empirical thermo-kinetic model to estimate the hardness of deposited layers based on different cooling cycles in a time-temperature-transformation (TTT) diagram. Further, the microstructural details obtained from the cross-sections of the clad were correlated with the estimated thermal cycles and hardness. A good correlation between the modeled and experimental results revealed that the developed model can be used to estimate the microstructural characteristics and mechanical properties of the H13 layer produced by the LC process.

Download Full-text

Effect of Tempering Temperature on Hardness and Microstructure of Laser Surface Remelted AISI H13 Tool Steel

Volume 1: Processes ◽

10.1115/msec2017-3014 ◽

2017 ◽

Cited By ~ 1

Author(s):

Debapriya Patra Karmakar ◽

Muvvala Gopinath ◽

Ashish Kumar Nath

Keyword(s):

Tool Steel ◽

Surface Hardening ◽

Laser Surface ◽

Water Quenching ◽

Laser Remelting ◽

Tempering Temperature ◽

H13 Tool Steel ◽

Laser Surface Remelting ◽

Aisi H13 ◽

Aisi H13 Tool Steel

Surface hardening was performed by laser surface remelting of AISI H13 tool steel samples using a high power fiber laser. The surface hardened samples were exposed to different tempering temperature of 500°C, 700 °C and 900 °C in a furnace for one hour and brought back to room temperature in still air and by water quenching. Changes of the laser remelted and hardened layer were investigated in terms of microstructure and hardness before and after exposure to different tempering temperatures. Laser remelting caused mainly dendritic microstructure at the top layer but the dendritic structure of the remelted layer got altered after tempering at high temperatures. Air and water quenching caused almost similar result during tempering of laser remelted layer. The microhardness variations along depth after tempering at different temperatures indicates that the surface hardening imparted by laser remelting remains almost intact up to 700 °C but gets destroyed at 900 °C. Although the experimental temperature limits gives approximate threshold values, but it provides a clear indication of a safe limit for laser surface hardened components in high temperature applications like hot-forging dies and friction stir welding tool, etc.

Download Full-text