Influence Of G35 Quenching Medium On The Microstructure And Mechanical Properties Of Medium-carbon And High-carbon Steel

Quenching medium is important for steels'microstructure and mechanical properties and energy saving, environmental protection.This paper is based on the water-soluble quenching medium JEF-G35 (G35), which is supplied by a quenching medium company at Zheng Zhou city. Adopt MEF-3 microscope, universal testing machine and scanning electron microscope etc, after a series of test, analysed the physical and chemical properties of G35 medium. In addition, we aimed at widely used medium-carbon steel 35CrMo and high-carbon antifriction bearing steel GCr15 in industry, adopt this quenching medium, then compared with frequently-used quenching medium water and oil, discussed G35 medium's adaptability on these two kinds of material.After the test, some basic conclusions obtained in this paper as follows:(1)G35 medium's PH is 6.7, assumes the low-acid. After long-term placement or quenching, it has no suspension and no deposits, otherwise, there is no blistering in quenching. With the G35 medium temperature increased, it's viscosity is decreased from 1.37197 mm~2/s to 0.55621mm~2/s, fell as much as 59.5%. Compared with others frequently-used medium, G35 quenching medium has less corrosive to steels. After 20h test, the GCr15 sample still has good metal glossiness on it's surface, there is not obvious corrosion.(2) Quenched at 840℃,35CrMo steels'microstructure is uneven, increasing the quenching temperature, we can obtain the better structure. Quenched at 860℃,samples can obtain the better mechanical property, it's impact absorbing energy as high as 164.101J, strength of extension is 805MPa.(3)With the G35 medium's concentration increasing, 35CrMo steel sample's martensite becomes coursing, and it's hardness decreased from 53.38HRC to 45 HRC, impact absorbing energy also decreased from 160.573J to 144.256J, but still exceed the sample's which is quenched in water. The medium's temperature raised, samples'hardness, impact absorbing energy and tensile strength is decreased.(4)GCr15 steel sample obtained big martensite at 860℃, than quenched at 820℃and 840℃; when the sample was quenched at 840℃, it can obtained high hardness 64HRC, Depth of hardened layer is 15mm, high impact toughness, compression strength and flexural strength. (5) When the G35's concentration increased to 25, black bulk will appear in the sample's microstructure. Depth of hardened layer is increased from10.7mm to 15mm, then decreased to 12.84mm. Flexural strength is decrease with the G35's concentration increase, but impact toughness is increase, amplification is 5J.Increased the G35's using temperature, the hardness is lower ,hardened layer is minished to 6.42mm at 80℃,the impact toughness and flexural strength is also decrease. The sample of GCr15 steel, it was quenched in G35 medium, it's hardness,flexural strength, compression strength and impact toughness are lie between water and oil.(6) Adopting G35 water solution as quenching medium, maximum deformation of opening is 0.10mm on the test block deformation of GCr15 steel, lying between water and oil samples'. it's minimum crack length 169.68mm and it's maximum 326.56mm also lying between water and oil quenched sample's.