D6AC Vac-Arc超高强度合金结构钢化学成分力学性能​

D6AC AlloySpecialty Alloys - High-Strength Alloy SteelsNominal Analysis0.46 C, 0.25 Si, 0.75 Mn, 1.10 Cr, 0.60 Ni, 1.00 Mo, 0.10 V, Bal. FeA medium carbon, low alloy, ultra high-strength steel primarily used for high strength structural applications requiring strength levels up to 280,000 psi. This alloy provides a high yield strength to tensile strength ratio, combined with good ductility. A tough and fibrous fracture is exhibited to as low as -210F (-134°C) in impact testing; also the notch toughness is excellent. It has been selected for fracture toughness critical applications at a variety of strength levels. The deep hardening characteristics has enabled the production of relatively large sections.D6AC Vac-Arc steel is produced by consumable electrode vacuum arc remelting process to impart cleanliness and preferred ingot structure, which in turn improves transverse mechanical properties.

美国于60 年代初开始研制D6AC，由AISI 4340 钢改进而成，被广泛用于制造战术和战略导弹发动机壳体及飞机结构件。到了70 年代中期，D6AC 逐渐取代了其它合金结构钢，成为一种制造固体火箭发动机壳体的专用钢种。美国新型地空导弹“爱国者”，小型导弹“红眼睛”，大中型导弹“民兵”、“潘兴”、“北极星”、“大力神”等，美国航天飞机的φ3.7m助推器壳体也采用D6AC 钢制造。D6AC 还曾用于制造F-111飞机的起落架和机翼轴等。

标准：

ASTM A29/A29M-04

化学成分：

碳 C ：0.38～0.43

硅 Si：0.15～0.35

锰 Mn：0.60～0.90

硫 S ：允许残余含量≤0.040

磷 P ：允许残余含量≤0.035

铬 Cr：0.60～0.90

镍 Ni：1.65～2.00

铜 Cu：允许残余含量≤0.025

钼 Mo：0.20～0.30

力学性能：

抗拉强度 σb (MPa)≥1280(100),

伸长率 δ5 (%)≥12,

断面收缩率 ψ (%)≥55,

冲击功 Akv (J)≥78,

冲击韧性值 αkv (J/cm2)≥98(10)

热处理规范：

淬火850℃,油冷;回火600℃,水冷、油冷。

交货状态：以热处理（正火、退火或高温回火）或不热处理状态交货，交货状态应在合同中注明。