摘 要:W18Cr4V作为高速钢，因其具有高红硬性、高耐磨性以及良好的淬透性，并且具有一定的韧性，在实际生产中常用来制造刃具和冷作模具。但是作为一种莱氏体钢，组织中存在大量的共晶碳化物，碳化物偏析严重，造成材料热塑性低，以致于在使用过程中发生脆性断裂。所以合适的热处理对于改善它的性能很有帮助。

本文主要对W18Cr4V高速钢进行热处理热处理工艺研究，首先对试样进行不同温度的球化退火，并采用蔡司显微镜观察金相组织并进行硬度分析，以确定最佳球化退火温度；然后随其进行淬火处理，确定最佳淬火温度，最后进行回火处理；从而确定最佳热处理工艺。实验结果表明，退火的最佳温度为温度为850℃，采用的退火工艺为等温球化退火。淬火的最佳温度为1260℃。回火时得到的最佳回火次数为三次回火。回火之后的硬度值比淬火之后有所增加，并且每次回火之后的硬度值也有所提升，从一次回火之后的61.2HRC增加到三次回火之后的62.4HRC，这是二次硬化的结果。

关键词：W18Cr4V；退火；淬火；回火；硬度

Abstract:W18Cr4V as high-speed steel, because of its high hardness, high wear resistance and good hardenability, and has a certain toughness,is commonly used to manufacture cutting tools and cold mold in the actual production. However, as a kind of ternary steel, there are a large number of eutectic carbides in the organization, so it has serious carbide segregation, resulting in low thermoplastic material.Brittle fracture often occurs during use. So the appropriate heat treatment to improve its performance is very helpful.

In this paper, the heat treatment of W18Cr4V high speed steel is studied. Firstly, the samples are subjected to spheroidizing annealing at different temperatures. The microstructure of the microstructure is observed by Zeiss microscope and the hardness is analyzed to determine the optimum spheroidizing annealing temperature. Then quenching treatment is operated to determine the best quenching temperature, and finally tempering is operated to determine the best heat treatment process.It is found that the optimum temperature for annealing is 850 ℃, and the annealing process is isothermal spheroidizing annealing. The optimum temperature for quenching is 1260℃. The best tempering times for tempering are three times of tempering. The hardness value after tempering is increased after quenching, and the hardness value after each tempering is also increased, from 61.2HRC after a tempering to 62.4HRC after three tempering, which is the result of secondary hardening.

Keywords: W18Cr4V; annealing; quenching; tempering;hardness

目  录

第一章 绪论 1

1.1 国内外研究现状 1

1.2 高速钢的组织及性能特点 3

1.2.1 合金元素在高速钢中的作用 3

1.2.2 高速钢的组织性能 4

1.3 高速钢的热处理工艺 4

1.3.1 退火工艺 4

1.3.2 淬火工艺 4

1.3.3 回火工艺 5

1.3.4 W18Cr4V高速钢淬火组织及缺陷 6

1.4 本文的主要研究内容 7

第二章 实验设备和实验方法 8

2.1 实验设备 8

2.2 实验方法 12

2.2.1 退火温度的选择 12

2.2.2 退火工艺方案的确定 12

2.2.3 淬火温度的选择 13

2.2.4 淬火介质的确定 13

2.2.5 回火工艺 14

第三章 实验结果分析 15

3.1 W18Cr4V钢退火处理 15

3.1.1 退火温度的确定 15

3.1.2 W18Cr4V钢退火工艺的确定 16

3.2 W18Cr4V钢淬火处理 17

3.2.1 淬火保温时间 17

3.2.2 试样的预热处理 18

3.2.3 W18Cr4V钢淬火温度的确定 18

3.2.4 W18Cr4V钢淬火介质的确定 20

3.3 W18Cr4V钢回火处理 20

3.3.1 回火时间 20

3.3.2 回火注意事项 21

3.3.3 回火温度 21

3.3.4 W18Cr4V钢回火次数的确定 21

3.4 硬度分析 23