Investigation of quenching stress of 42CrMo treated by alternately timed quenching process

Abstract

ABSTRACTAlternately timed quenching (ATQ) technology includes ATQ process and equipment. ATQ process essentially executes multicycle quenching-partitioning-tempering (MQ-P-T) process by alternative water -quenching and air cooling. Engineering applications indicate that ATQ process not only can replace oil or aqueous polymer solution quenching, but also reach even be superior to the mechanical properties of workpieces quenched by oil or aqueous polymer solution. Since direct water-quenching usually causes the cracking of workpieces, polluting oil quenching or aqueous polymer solution quenching is still used in modern industry. The combination of water-quenching and air-cooling can effectively avoid the cracking of workpieces, but direct water-quenching (DQ) process very easily causes cracking, and this issue puzzles us for a long time. In this work, 42CrMo cylinder with 60 mm in diameter respectively treated by ATQ process and DQ process for comparison is taken an example, and the quenching stress of 42CrMo cylinder is investigated by the finite element simulation (FES) and X-ray diffraction (XRD) measurement, respectively. The results reveals the origin of avoiding cracking of workpieces for ATQ process, that is, ATQ process markedly lowers the quenching tensile stress and raises its uniform distribution compared with DQ process.