The influence of laser pulse shape in repair welding of tool steels

Abstract

The majority of tool steels are commonly considered as non-weldable because of their high carbon and high alloy elements content. Repair welding of such steels with conventional methods is very difficult due to cracking during remelting or cladding and is generally performed with preheating. Besides its common benefits, repair welding with laser technology also offers a possibility of tool repair without preheating. This paper presents the influence of different pulse shapes on welding of high carbon, high chromium tool steel with the pulsed Nd:YAG laser. Repair welding tests were carried out on AISI D2 tool steel which is commonly used for deep drawing, blanking, forming and thread rolling dies; shear and granulator blades and high wear resistant and intricate moulds for plastic injection. The steel specimens were quenched and tempered to hardness of 56 HRc. Afterwards, microstructural analysis, micro-hardness analysis and investigation of defects with scanning electron microscopy were carried out. The test results suggest that it is possible to obtain sound welds without preheating, with the right selection of welding parameters and appropriate pulse shape.The majority of tool steels are commonly considered as non-weldable because of their high carbon and high alloy elements content. Repair welding of such steels with conventional methods is very difficult due to cracking during remelting or cladding and is generally performed with preheating. Besides its common benefits, repair welding with laser technology also offers a possibility of tool repair without preheating. This paper presents the influence of different pulse shapes on welding of high carbon, high chromium tool steel with the pulsed Nd:YAG laser. Repair welding tests were carried out on AISI D2 tool steel which is commonly used for deep drawing, blanking, forming and thread rolling dies; shear and granulator blades and high wear resistant and intricate moulds for plastic injection. The steel specimens were quenched and tempered to hardness of 56 HRc. Afterwards, microstructural analysis, micro-hardness analysis and investigation of defects with scanning electron microscopy were carried out. The t...