가스 ?칭 방법

• Main Authors: SUGIMOTO TSUYOSHI, OKAYAMA YUKICHI
• Format: Patent
• Language: Korean
• Published: 04.07.2018
• Subjects: CHEMISTRY; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS

본 발명의 가스 ?칭 방법은, 냉각용 가스가 강제적인 순환에 의해 워크를 급냉하는 제1 단계(t1 내지 t2)와, 냉각용 가스의 순환을 정지함과 함께 노 내를 감압하여 단열하는 제2 단계(t2 내지 t3)와, 냉각용 가스에 의해 다시 워크를 냉각하는 제3 단계(t3 이후)를 포함한다. 제2 단계에서는, 마르텐사이트 변태 개시 온도보다도 높은 중간 온도로 워크가 유지되고, 이 사이에, 워크 각 부가 균열화된다. 따라서, 균일한 ?칭을 실현할 수 있고, 냉각 속도의 차이에 의한 왜곡을 억제할 수 있다. A gas quenching method of the present invention includes a first stage (t1 to t2) at which a workpiece is subjected to a rapid cooling by forcibly circulating a cooling gas, a second stage (t2 to t3) at which the circulation of the cooling gas is stopped and pressure is reduced inside the furnace to conduct heat insulation, and a third stage (as from t3) at which the workpiece is cooled again by the cooling gas. At the second stage, the workpiece is maintained at an intermediate temperature that is higher than martensite transformation start temperature, and, during this, temperature throughout the workpiece is made uniform. Therefore, it is possible to achieve a uniform quenching and suppress distortion caused by difference of the cooling speed.