MULTIPLE HEAT TREATMENT STEEL HAVING EXCELLENT LOW TEMPERATURE TOUGHNESS FOR ENERGYAND MANUFACTURING METHOD THEREOF

• Main Authors: CHAE, JAE YONG, KIM, DAE WOO, UM, KYUNG KEUN
• Format: Patent
• Language: English; Korean
• Published: 05.07.2016
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

A multiple heat treatment type energy steel of the present invention can be manufactured by a manufacturing method of a process of performing slab reheating - rolling - at least two heat treatments - tempering heat treatment of a steel piece selected from a group including, by wt%, C: 0.08-0.12%, Si: 0.3% or less, Mn: 1.0-1.5%, Al: 0.01-0.1%, Nb: 0.01% or less, Ni: 3.0-5.0%, Cr: 1.0% or less, Mo: 1.0% or less, Ti: 0.05% or less, V: 0.1% or less, P: 0.01% or less, S: 50 ppm or less, N: 60 ppm or less. According to the present invention, provided are the multiple heat treatment type energy steel having excellent low temperature toughness which has yield strength equal to or more than 790 MPa and has excellent impact toughness equal to or more than 50 J at a low temperature of -60°C, by miniaturizing crystal grains by a method of repeating a re-heat treatment process heating the steel to an Austenite generation temperature range, and the manufacturing method thereof. 본 발명의 다중 열처리형 에너지용 강재는, 중량%로, C: 0.08~0.12%, Si: 0.3%이하, Mn: 1.0~1.5%, Al: 0.01~0.1%, Nb: 0.01%이하, Ni: 3.0~5.0%, Cr: 1.0%이하, Mo: 1.0%이하, Ti: 0.05%이하, V: 0.1%이하, P: 0.01%이하, S: 50ppm이하, N: 60ppm이하를 포함한 그룹으로부터 선택된 강편을 슬라브 재가열 - 압연 - 적어도 2회 이상 열처리 - 템퍼링 열처리의 과정의 제조방법을 통해 제조할 수 있다. 본 발명에 따르면, 오스테나이트 생성 온도 영역까지 가열하는 재열처리 과정을 반복해서 실시하는 방법으로 결정립을 미세화하여 790MPa 이상의 인장강도와 -60℃의 저온에서도 50J 이상의 우수한 충격인성을 가지는 저온인성이 우수한 다중 열처리형 에너지용 강재 및 그 제조방법을 제공한다.