Study On Quenching Cooling Property And Thermochemical Stability Of PAG Quenching Medium

Quenching process is one of the most important steps to obtain the required structure and properties in the heat treatment process.Defects such as quenching deformation,crack,soft spot and lack of penetration caused by quenching often appear in the quenching workpiece.Using this quenching medium correctly can successfully solve the technical problem that many workpieces with complex shapes will crack when quenching with water but will not be hardened when quenching with oil.Since the introduction of PAG water-soluble quenching medium in China in the 1990 s,its excellent performance has made it widely used in factories to replace water and quenching oil.In this paper,the physical and chemical parameters and quenching process,thermal and chemical stability of the environmental performance of volatile emission and quenching cooling characteristics and artifacts induced crack characteristics of three kinds of PAG water soluble quenchant: imported 75-H-380000 in the United States,imported W55000 in South Korea and the research development of domestic HS brand KLM-165 Q had been studied and water and quench oil had been chosen to be a systematic comparison.The main conclusions are as follows:(1)The three PAG water-soluble quenching mediums have similar physical and chemical parameters,similar thermal stability and small error variations.(2)The content of harmful substances in quenching oil fume is significantly higher than that in PAG quenching medium,while the content of harmful substances in domestic PAG medium is slightly higher than that in imported PAG medium from the United States.Both domestic and imported PAG water-soluble quenching media have good environmental performance.(3)The maximum cooling rate of domestic HS brand klm-165 q PAG solution is greater than that of PAG solution imported from the United States and South Korea at all concentrations.The quenching and cooling characteristics of domestic and imported PAG water-soluble quenching medium can be controlled and adjusted according to quenching process requirements between the cooling properties of water and quenching oil.(4)The service stability of domestic HS brand klm-165 q PAG solution decreases with the extension of service time,and its cooling rate after 18 months is close to the cooling rate of tap water,which increases the possibility that the workpiece is likely to be quenched in the quenching process.(5)Compared with water quenching and oil quenching,the microstructure obtained by PAG solution quenching is uniform and martensite is lamellar,which can completely meet the quenching process requirements.All quenching media have the tendency to induce cracks,but the cracks in water quenching state are strong and grow fast,while the cracks in PAG solution and oil quenching state are small and grow slowly.(6)Self-developed domestic PAG water-soluble quenching medium has good aging resistance and durability,which can completely replace imported similar products for production and marketing.This product has considerable social and economic benefits and the prospect of promotion and use.