METHOD FOR MANUFACTURING A QUENCHED AND TEMPERED SEAMLESS PIPE FOR A HIGH-STRENGTH HOLLOW SPRING

• Main Authors: TANGE, Akira, HATANO, Hitoshi, KURIMOTO, Kiyoshi, GOTO, Yurika, KOCHI, Takuya
• Format: Patent
• Language: English; French; German
• Published: 14.08.2019
• 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; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

To provide a method for manufacturing steel for a high-strength hollow spring that exhibits excellent resistance to hydrogen embrittlement. Disclosed is a method for manufacturing steel for a hollow spring obtained by quenching and tempering a seamless pipe for use as a material of the hollow spring, wherein the seamless pipe including predetermined components is subjected to a heat treatment is performed to satisfy quenching conditions (1) mentioned below, and to satisfy tempering conditions (2) mentioned below, (1) quenching conditions: 26 , 000 ‰¤ T 1 + 273 × log t 1 + 20 ‰¤ 29 , 000 900 °C ‰¤ T 1 ‰¤ 1 , 050 °C , 10 seconds ‰¤ t 1 ‰¤ 1 , 800 seconds , where T1 is a quenching temperature (°C), and t1 is a holding time (seconds) in a temperature range of 900°C or higher, and (2) tempering conditions: 13 , 000 ‰¤ T 2 + 273 × log t 2 + 20 ‰¤ 15 , 500 T 2 ‰¤ 550 °C , and t 2 ‰¤ 3 , 600 seconds , where T2 is a tempering temperature (°C), and t2 is a total time (seconds) from start of heating to completion of cooling.