YFFB扁电缆 春晨 起重机扁电缆

江苏春晨电缆有限公司生产YFFB扁电缆 春晨 起重机扁电缆，YFFB扁电缆 春晨 起重机扁电缆，

常用带电作业承力工具材料的疲劳特性

Fatigue characteristics of common live working tool materials

金属材料的疲劳特性：影响金属材料疲劳特性的因素很多，除受成分、夹杂物和热处理的影响外，还有其他因素。

Fatigue characteristics of metal materials: there are many factors that affect the fatigue characteristics of metal materials, besides the influence of composition, inclusions and heat treatment, there are other factors.

金属材料表面加工、尺寸和应力集中的影响：工具部件承受弯曲和扭转载荷时表面应力大，疲劳破坏多数自表面开始。粗糙的表面状态相当于存在很多微缺口，由缺口应力集中而导致疲劳强度降低。表面越粗糙，疲劳强度降低得越严重。有圆角、油孔和螺纹键槽等缺口的部件，因应力集中导致部件疲劳强度降低。缺口越尖锐应力越集中，疲劳强度降低越严重。

The influence of surface processing, dimension and stress concentration of metal materials: the surface stress of tool parts under bending and torsion load is the largest, and most of the fatigue damage starts from the surface. The rough surface state is equivalent to the existence of many micro notches, which lead to the reduction of fatigue strength due to the stress concentration of the notches. The rougher the surface is, the more serious the fatigue strength is. The fatigue strength of parts with round corner, oil hole, thread keyway and other notches is reduced due to stress concentration. The sharper the notch, the more concentrated the stress, the more serious the fatigue strength reduction.

部件表面镀层对其疲劳强度也有影响：工具表面镀层主要是铬（Cr）和镍（Ni），镀这两种金属时造成疲劳极限大为降低的主要原因是镀层中产生很大的残余拉应力。由于镀层中存在很多微细龟裂纹，它作为缺口使应力集中。如30CrMo材料未镀前的疲劳极限为72.5MPa。镀0.25mm厚的Cr后，其疲劳极限则为50.6MPa，仅为镀前的68%。

The coating on the surface of parts also has some influence on its fatigue strength: the coating on the surface of tools is mainly chromium (CR) and nickel (Ni). The main reason for the great reduction of fatigue limit caused by the plating of these two metals is the large residual tensile stress in the coating. Because there are many micro tortoise cracks in the coating, it acts as a notch to make the stress concentration. For example, the fatigue limit of 30CrMo material before plating is 72.5mpa. After plating 0.25mm Cr, the fatigue limit is 50.6mpa, only 68% of that before plating.

热处理对其疲劳强度的影响：通过加热、保温和冷却等步骤来调整金属内部组织，改善材料性能的技术手段，称为热处理。热处理可分为退火、亚火、回火和淬火等。退火即随炉冷却，亚火即空气冷却，淬火即用水突然冷却，回火即再加温。退火和亚火可提高机械性能，降低硬度，提高塑性和内应力，淬火是为了得到高硬度和高耐磨性，以得到强度与塑性的良好配合，回火是为了防止淬火引起的内应力和脆性。

The influence of heat treatment on its fatigue strength: the technical means to adjust the internal structure of metal and improve the performance of material through heating, heat preservation and cooling, is called heat treatment. Heat treatment can be divided into annealing, sub fire, tempering and quenching. Annealing is cooling with furnace, sub fire is cooling with air, quenching is cooling suddenly with water, tempering is heating again. Annealing and tempering can improve mechanical properties, reduce hardness, improve plasticity and eliminate internal stress. Quenching is to obtain high hardness and high wear resistance, so as to obtain a good combination of strength and plasticity. Tempering is to prevent internal stress and brittleness caused by quenching.