张新的毕业设计.doc

西安航空职业技术学院 毕 业 设 计（论 文） 论文题目： 45钢淬火开裂控制 　所属系部： 航空材料工程学院 指导教师： 苗高蕾 学生姓名： 张新 学号: 专　　业： 金属材料与热处理 西安航空职业技术学院制 2013.10.21  摘 要 45钢件在淬火处理时易出现淬裂现象。研究表明:?4mm～?12mm的45钢件在830℃～850℃×1.1min/mm～1.2min/mm的加热和保温条件下淬入清水或10%的盐水中易出现裂而采取加大工艺预留量(13mm～14mm)、避开危险尺寸(4mm～12mm)、低温(750℃～760℃ )淬火、控制加热温度(780℃～790℃)以及保温时间和回火时间等措施,可有效防止45钢件淬火时出现裂纹现象.对于截面尺寸在4mm～12mm的零件,采用低温淬火其淬火合格率99%. 本文分析了45钢材料热处理特性，改变了传统45钢热处理淬火加热方式及冷却介质，有效控制了45钢热处理淬火裂纹，提高了45钢热处理质量。 关键词：淬火、45钢、裂纹、回火 Abstract : The 45 steel parts easily come out the quenching crack phenomenon during quenching treatment. The research shows :45 steel parts of ?4 mm ～ ? 12 mm easily appears the quenching cracks in clear water or 10 % salt water under the condition of heating at 830 ℃ ～ 85 ℃×1.1min/mm～1.2min/mm and keeping warm. However it can take some measures to enlarge the technological allowance amount (13 mm ～ 14mm ) ,avoiding the dangerous dimensions ( 4 mm ～ 12 mm ) by quenching at low temperature ( 750 ℃ ～ 760 ℃ ) then controlling the tem perature ( 780 ℃ ～ 790 ℃ ) of heating ,the time of keeping warm and the time of tem pering and so on .All these can be effective to prevent the 45 steel parts from the crack phenomenon as quenching Re 2 garding the parts sf the section dimension at 4 mm ～ 12 mm,the quenching qualified rate of the parts is over 99% by adopting the low tem perature quenching. This paper analyzes the characteristics of heat-treated steel 45 , 45 steel has changed the traditional way of heat treatment and quenching cooling medium, the effective control of 45 steel heat treatment and quenching cracks, an increase of 45 steel heat treatment quality. Key Words : 45 steel parts ;quenching crack ;dangerous dimension  目录 1.绪言 1 2. 45钢材料特性 1 2.1 化学成分和属性? 1 2.2 材料性能? 1 2.3 材料用途? 1 3.裂纹分类 3 4.1纵向裂纹形成原因 4 4.2横向裂纹形成原因...........................................................