Cold work tool material and method of manufacturing cold work tool

Patent metadata

Field	Value
Publication number	US-9890435-B2
Application number	US-201514914380-A
Country	US
Kind code	B2
Filing date	Sep 2, 2015
Priority date	Sep 26, 2014
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

A cold work tool material has an annealed structure including carbides, and a composition including, in mass %, C: 0.80% to 2.40%, Cr: 5.0% to 15.0%, Mo and W contained alone or in combination in an amount of (Mo+½W): 0.50% to 3.00%, and V: 0.10 to 1.50%, and adjusted such that the material has a martensitic structure by quenching. The material includes a cross sectional region of an annealed structure and a length of 90 μm and a width of 90 μm and including no carbides having a circle equivalent diameter exceeding 5.0 μm. In the cross sectional region, a proportion of a number of carbides B having a circle equivalent diameter of more than 0.1 μm and not more than 0.4 μm to a number of carbides A having a circle equivalent diameter of exceeds 0.1 μm and not more than 2.0 μm is greater than 80.0%.

First claim

The invention claimed is:

1. A cold work tool material used after quenched and tempered, having an annealed structure including carbides,
wherein the cold work tool material has a composition including, in mass %, C: 0.80% to 2.40%, Cr: 5.0% to 15.0%, Mo and W alone or in combination in an amount of (Mo+½W): 0.50% to 3.00%, and V: 0.10 to 1.50%, the composition being adjusted such that the material has a martensitic structure by the quenching,
wherein the cold work tool material includes a cross sectional region of an annealed structure, the region having a length of 90 μm and a width of 90 μm and including no carbides having a circle equivalent diameter exceeding 5.0 μm,
wherein, in the cross sectional region, a proportion of a number of carbides B having a circle equivalent diameter of more than 0.1 μm and not more than 0.4 μm to a number of carbides A having a circle equivalent diameter of more than 0.1 μm and not more than 2.0 μm is greater than 80.0%, and
wherein the cold work tool material is produced by casting an ingot and hot working the ingot.

2. A method of manufacturing a cold work tool, comprising a step of quenching and tempering the cold work tool material according to claim 1 .

3. The cold work tool material according to claim 1 , wherein, in the cross sectional region, a number density of the carbides A is not less than 9.0×10 5 per mm 2 , and a number density of the carbides B is not less than 7.5×10 5 per mm 2 .

4. A method of manufacturing a cold work tool, comprising a step of quenching and tempering the cold work tool material according to claim 3 .

Assignees

• Hitachi Metals Ltd

Inventors

• Shouji Tatsuya
• Mishima Setsuo
• Taniguchi Toru
• Kuroda Katsufumi

Classifications

• C22C38/02

  containing silicon · CPC title

• C22C38/24

  with vanadium · CPC title

• C21D1/18 Primary

  Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62) · CPC title

• C21D9/0068

  for particular articles not mentioned below · CPC title

• C22C37/06

  containing chromium · CPC title