Research And Application Of Alternately Timed Quenching Equipment By Water Air

Because the present equipments can not satisfy the requirement for alternately timed quenching process, the feasibility of alternately timed quenching (ATQ) process with water and air as quenching media was investigated in this paper. Experimental results indicate the discretionary cooling curves for air and water can be controlled by adjusting periods of water quenching and air cooling. Further measurements of quenching boundaries, simulations of the ATQ processes, microstructure characterizations and mechanical property tests of practical productions such as flange shafts, flat die steels and large marine crankshafts were carried out. Based on these works, assembled features for the ATQ process facilities were clarified. Severe unique quenching equipment special for the ATQ process were designed and made for the production of flange shafts, flat die steels and marine crankshafts.At first, cooling curves and heat transfer coefficients for water in three cases of immersion,injection and injection-immersion quenching respectively were determined experimentally. It is found that heat transfer coefficients for water in injection and injection-immersion quenching are almost same, however, transfer coefficients in immersion quenching has smaller values due to the existence of thick steam film in the range of temperature 500℃-850℃. The integral areas of heat transfer coefficient versus temperature in injection and injection-immersion quenching are evaluated 5 times the value in immersion quenching in the range of 500℃-850℃, and then reduced to be 2.5 times below the temperature of 500℃. The founding will be useful to conduct the ATQ process avoiding quenching distortion by adjusting the cooling ability between 1-5 times of water.In the present study, the feasibility of alternately timed quenching (ATQ) process with water and air as quenching media was investigated. Experimental results indicate any cooling curve for air and water can be achieved by adjusting periods of water quenching and air cooling. In addition, this paper proposes several functions which the ATQ equipments should provide, and gives a reference for designing such equipments.The ATQ process requires the quenching equipment be able to transfer the work piece between water quenching and air cooling at the exact time rapidly and frequently. Therefore, several types of ATQ quenching equipment for different work pieces were designed respectively.For the 42CrMo4 flange shafts of wind power equipment,Multi-position ATQ quenching equipment was designed, and a process of immersion quenching without moving the equipment was realized by completion of ascending and descending of the fluid level of quenching media. A system of quench tank sharing a rapid injection system was established by virtue of supplying the quenching media into several quench tank through a public channel.For the manufacture of 1Cr12Mo flat die steel, the design of online ATQ quenching equipment solving the sealing between roll tables and quenching tank realizes the online immersion quenching under the transition of roll tables, which provide a novel way to treat such large size work piece.The above equipment only designed for the heat-treatment of steels with relatively simple shapes. 42CrMo4 Marine crankshaft with length of 4000-6500 mm, spindle diameter of 180-350 mm and weight of over 5 tons requires high mechanical properties at half radius. The ATQ quenching equipment special for the large work piece with extremely complex shapes was designed and manufactured. The original proposal of the combination of immersion quenching, injection quenching and air cooling by hanging the crankshafts was patent successfully. Homogeneous cooling of the cranks with similar heat transfer coefficients during quenching is realized and quenching distortion is controlled well, less than 8 mm of axial deformation during the crank quenching with 6000 mm length by immersion quenching and injection quenching simultaneously. The implicating example shows that the mechanical properties 42CrMo4 marine cranks in this study meet the requirements and no extra alignment is need.It was also found that severe composition segregation in the cranks observed metallographic can't be eliminated by adjusting the ATQ processes. The author suggested the segregation is solved by improving the calendaring process of original steels previously.