合金结构钢主要特征：经调质处理后，具有良好的综合力学性能、低温冲击韧度及低的缺口敏感性，淬透性良好，油冷时可得到较高的疲劳强度，水冷时复杂形状的零件易产生裂纹，冷弯塑性中等，回火或调质后切削加工性好，但焊接性不好，易产生裂纹，焊前应预热到100～150℃，一般在调质状态下使用，还可以进行碳氮共渗和高频表面淬火处理。应用举例：调质处理后用于制造中速、中载的零件，如机床齿轮、轴、蜗杆、花键轴、顶针套等，调质并高频表面淬火后用于制造表面高硬度、耐磨的零件，如齿轮、轴、主轴、曲轴、心轴、套筒、销子、连杆、螺钉螺母、进气阀等，经淬火及中温回火后用于制造重载、中速冲击的零件，如油泵转子、滑块、齿轮、主轴、套环等，经淬火及低温回火后用于制造重载、低冲击、耐磨的零件，如蜗杆、主轴、轴、套环等，碳氮共渗处即后制造尺寸较大、低温冲击韧度较高的传动零件，如轴、齿轮等。 Alloy structural steel main features: after tempering treatment, has the good comprehensive mechanical properties, low temperature impact toughness, and low notch sensitivity, good hardenability, oil cooling can get higher fatigue strength, water-cooled complex shape parts easy to generate crack, plastic medium, cold bending tempered or quenched and tempered after cutting workability is good, but the weldability isn't good, easy to produce cracks, should be preheated to 100 ~ 150 ℃ before welding, generally used in the quenched and tempered state, also can undertake carbonitriding and high-frequency surface hardening treatment. Application, for example: after the tempering process used in the manufacture of medium speed, the load of the parts, such as gear, shaft, worm, spline shaft, thimble set, such as high frequency surface after quenching tempering and used in the manufacture of high surface hardness, wear resistance parts, such as gear, shaft, shaft, crankshaft, spindle, sleeve, pin, connecting rod, screw nut, inlet valve, etc., after quenching and tempering temperature in the parts used in the manufacture of heavy, medium speed impact, such as oil pump rotor, slider, gear, shaft, sets of ring, etc., used in the manufacture of reloading after quenching and low temperature tempering, low impact, wear-resistant parts, such as worm, such as main shaft, shaft, thimble, carbonitriding place namely after manufacture large size, high low-temperature impact toughness of the transmission parts, such as axle, gear, etc.