In the present work, paraffin phase change material is used as quenchant for the heat treatment of 42CrMo4 alloy and compared with water, air, and CuO doped paraffin. The samples were prepared based on ASTM E 8M-98 standard for tensile test and then heated up to 830 °C, kept for 4 h in an electric resistance furnace and then quenched in the mentioned media. Elastic modulus, yield strength, ultimate tensile strength, elongation, and modulus of toughness were determined according to the obtained stress-strain curves. Moreover, the hardness and microstructural evolution were investigated after the heat treatment at different media. The samples quenched in paraffin and CuO-doped paraffin are higher in ultimate tensile strength (1439 and 1306 MPa, respectively) than those quenched in water (1190 MPa) and air (1010 MPa). The highest hardness, with a value of HV 552, belonged to the sample quenched in CuO-doped paraffin. The microstructural studies revealed that the non-tempered steel had a ferrite/pearlite microstructure, while by quenching in water, paraffin and CuO-doped paraffin, ferrite/martensite microstructures were achieved. It is also observed that using the air as quenchant resulted in a three-phase bainite/martensite/ferrite microstructure.

在目前的工作中，石蜡相变材料用作42CrMo4合金热处理的淬火剂，并与水，空气和CuO掺杂的石蜡进行比较。样品是根据ASTM E 8M-98标准进行拉伸试验而制备的，然后加热至830°C，在电阻炉中放置4 h，然后在上述介质中淬火。根据获得的应力-应变曲线确定弹性模量，屈服强度，极限抗拉强度，伸长率和韧性模量。此外，还研究了在不同介质下热处理后的硬度和微观组织演变。用石蜡和CuO掺杂的石蜡淬火的样品的极限抗拉强度（分别为1439和1306 MPa）要比在水（1190 MPa）和空气（1010 MPa）中淬火的样品更高。最高硬度 HV 552的值属于在掺杂CuO的石蜡中淬火的样品。显微组织研究表明，未回火的钢具有铁素体/珠光体的显微组织，而通过在水中淬火，石蜡和掺杂CuO的石蜡，可获得铁素体/马氏体的显微组织。还观察到，使用空气作为淬火剂会导致三相贝氏体/马氏体/铁素体微观结构。