英语翻译Some product applications require properties of hardness and strength to resist penetration under high pressure and to provide maximum wear qualities only on the surface .Where through hardness and the maxium strength associateed with it

英语翻译Some product applications require properties of hardness and strength to resist penetration under high pressure and to provide maximum wear qualities only on the surface .Where through hardness and the maxium strength associateed with it
英语翻译
Some product applications require properties of hardness and strength to resist penetration under high pressure and to provide maximum wear qualities only on the surface .Where through hardness and the maxium strength associateed with it are not necessary,it may be more economical to gain the needed surface qualities by a casehardening process.Casehardening involves a change of surface properties to produce ahard,wear-resistant shell about atough,fracture-resistant core.
Casehardening of steel may be accomplished by a number of methods.Choice between them is dependent on the material to be treated,the application,and the desired properties.One of the more common methods is carburizing,which implies an increase or addition of carbon which is actually the basis of the prcess.
Performed on Low Carbon Steels.Carburizing is usually performed on a low alloy or plain low carbon steel.If an alloy stell is used,it usually contains small quantities of nickel or some other element that acts as a retardant to grain growth during the heating cycle.Low carbon steels are commonly used to minimize the effect of subsequent heart tretments on the core material.It is possible to carburize any steel containing less than the 0.70%~1.20% carbon that is produced in the surface material.
Carbon Diffusion Is Time-temperratrue Dependent.Carbon is caused to diffuse into the steel by heating the material above its critical temperature and holding it in the presence of excess carbon.Temperatures used are usually between 850℃and930℃,with the chocice most dependent on the desired rate of penetration,the desired sutface carbon content,and the permissible grain growth in the material.Pentration is dependent upon both the temperature and time,with variation of case depth from 0.25 to 1.0 millimeter(0.010-0.040 inch) possible in the first 2 hours by varying the tempereature between the two extremes.The rate of penetration slows down as the depth increases,as shown in Fig.11-1,so that for large depths,relatively long periods of time are necessary.

英语翻译Some product applications require properties of hardness and strength to resist penetration under high pressure and to provide maximum wear qualities only on the surface .Where through hardness and the maxium strength associateed with it
一些新产品为了抵御高压渗透并提供仅磨损表面的最高品质,它们的应用需要硬度和强度的各方面性能.凡通过硬度和最大强度的地方与产品的关联不是很有必要的话,为了获得所需要的表面品质,由硬度加强进程可能会更符合经济效益,硬度加强涉及改变表面性质,涉及产生耐磨材料壳,裂痕抗核心.
加强刚的硬度可以通过一些方法来实现.选择它们要依赖于材料的处理,应用以及所期望的性能.较常见的方法是渗碳,这意味着增加或除碳,这其实是该进程的基础步骤.
对低碳钢,渗碳通常是一种低合金或纯低碳合金刚,它通常含有少量的镍或其他一些元素,作为阻燃剂,以晶粒生长期间供暖,碳钢普遍用来减少其在对心脏治疗影响的核心材料.它是可能的渗碳钢,任何含有少于0.70 ％ 〜 1.20 ％碳是产生于表面的材料.
碳扩散既费时又对温度依赖性.碳是造成扩散到钢的加热物质高于其临界温度的主要因素和使其存在过剩的碳.使用温度通常介乎于850 ℃ -930 ℃ ,与所选择的物质最大程度依赖于预想的渗透速度,理想的表面碳含量和容许晶粒生长的物质.渗透取决于双方的温度和时间,温度的有可能在前2小时随着变异案例深度由0.25至1.0毫米（ 0.010-0.040英寸）有所改变,渗透的速度因深度的增加而放慢,如图所示,在图11 – 1中 ,深度增加,相对的加长时间是很必要的.
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