CN101993983B - Annealing method for improving machinability of martensitic stainless steel cast - Google Patents

Abstract

The invention discloses an annealing method for improving the machinability of a martensitic stainless steel cast, which comprises the following steps of: (1) paving limestone granules in a cast annealing container; (2) paving lime powder; (3) placing a cast to be annealed in the cast annealing container; (4) adding the lime powder for covering the cast; (5) covering with the limestone granules; and (6) taking the cast out after the cast is cooled to room temperature. Compared with the traditional method, since the lime powder is used in the annealing method for improving the machinability of the martensitic stainless steel cast for isolating from outside air and humidity completely, hydrogen and nitrogen in the cast can disperse to the outside in one direction, thereby improving the machinability of the cast; moreover, the annealing method has simple process, is easy to operate, reduces the annealing cost and improves the economic benefit of enterprises.

Description

A kind of method for annealing that improves Martensite Stainless Steel foundry goods cutting ability

Technical field

The present invention relates to a kind of working method of Martensite Stainless Steel, belong to metallurgical technology field, a kind of specifically method for annealing that improves Martensite Stainless Steel foundry goods cutting ability.

Background technology

For improving the cutting ability of Martensite Stainless Steel; Like 30Cr13,40Cr13,70Cr17,90Cr18; When carrying out anneal, traditional annealing process generally adopts special-purpose lehre that foundry goods is heated to the annealing temperature of regulation, stops heating subsequently; Foundry goods rests on the interior furnace cooling of lehre to room temperature, takes out the back foundry goods is carried out cut.The weak point of this method for annealing is: owing to must take special-purpose lehre; Heating and furnace cooling are all in same stove; The utilising efficiency of lehre is lower, and the hardness of annealing back foundry goods promptly is between HRB 220-280, and machinability is still undesirable.

Summary of the invention

The object of the present invention is to provide that a kind of technology is simple, operation easily, reduce annealing cost, can improve a kind of method for annealing that improves Martensite Stainless Steel foundry goods cutting ability of foundry goods cutting ability.

In order to reach above purpose, the technical scheme that the present invention adopted is: a kind of method for annealing that improves Martensite Stainless Steel foundry goods cutting ability is characterized in that it may further comprise the steps completion:

(1), in the foundry goods take-in box, lay limestone particle:

The laying depth of limestone particle is 1-2 a times of casting thickness;

(2), lay lime powder:

The laying depth of lime powder is 2-3 a times of casting thickness;

(3), need insert in the foundry goods take-in box by the annealed foundry goods:

Foundry goods taken out in the heat tracing stove puts into the foundry goods take-in box immediately, the distance of the inner side-wall of foundry goods and foundry goods take-in box be casting thickness 3-5 doubly;

(4), add lime powder and cover foundry goods:

The cladding thickness of lime powder is 1.52 times of casting thickness;

(5), cover limestone particle:

The cladding thickness of limestone particle is 20-60mm;

(6), treat to take out foundry goods behind the foundry goods cool to room temperature.

The present invention also implements through following measure: described foundry goods take-in box is casing or heatable adobe sleeping platform.

Described limestone particle particle diameter be 3mm-10mm, need be preheating to 200 ℃-300 ℃ before use.

Described lime powder, wherein the content of CaO is crossed 80 mesh sieves more than 85%, need be preheating to 200 ℃-300 ℃ before use.

At casing or melt pit bottom increase limestone particle mainly is to increase the bottom supporting capacity; It mainly is to suppress lime powder to diffuse that top adds limestone particle; Be lime powder after the limestone particle decomposes, can not pollute the lime powder of adding, after foundry goods takes out; Adopt the screening mode can separate lime powder and limestone particle, realize recycling.The thermal conductivity of quicklime own is low, and the lime powder granularity is tiny, and gap between particles is very little; Very thin powder can be used as lagging material, reduces speed of cooling, and is also slower with lehre refrigerative speed than traditional; Adopting traditional lehre technology can not completely cut off outside air, hydrogen, nitrogen, oxygen simultaneously contacts with foundry goods; Adopt this craft stone ashes to possess the effect that secluding air contacts with foundry goods, lime powder has very strong moisture absorption characteristic, and airborne moisture does not contact with foundry goods; Hydrogen in the foundry goods, nitrogen can improve the inner quality of foundry goods by foundry goods to the outside unidirectional diffusion of foundry goods.

Beneficial effect of the present invention is: with the lehre of present use Martensite Stainless Steel is carried out the annealed method and compare, because whole annealing process is the heat that utilizes foundry goods heat-processed, need not increase outside heat; Vacate special-purpose lehre; Improved the lehre utilising efficiency, utilized lime powder powder minim gap realization heat preservation effect, utilized lime powder powder and extraneous air and moisture isolated fully than the good cooling results in the lehre; Hydrogen in the foundry goods, nitrogen can be to the outside unidirectional diffusions of foundry goods; Improve the cutting ability of foundry goods, and technology simply, operate, reduced annealing cost easily, improved economic benefit of enterprises.

Embodiment

Embodiment 1

40Cr13 foundry goods net thickness is 20mm, and physical dimension diameter 200mm adopts casing 400 * 400mm, and the 30mm limestone particle is laid in the bottom; Lay the 50mm lime powder above, the foundry goods that is heated to 1020 ℃ is taken out from the heat tracing stove, put into casing immediately; Filled out foundry goods and covered cladding thickness 40mm, surface coverage 20mm limestone particle with lime powder; Foundry goods reached room temperature after 96 hours, take out and carry out turning processing, and hardness HRB 230; Turning speed is 100-120m/s, and than 60-80m/s raising in the past, surface smoothness reaches Ra3.2.

Embodiment 2

70Cr13 foundry goods net thickness is 100mm, and physical dimension diameter 800mm adopts melt pit 1200 * 1200mm, and the 150mm limestone particle is laid in the bottom; Lay the 200mm lime powder above, the foundry goods that is heated to 920 ℃ is taken out from the heat tracing stove, put into melt pit immediately; Filled out foundry goods and covered cladding thickness 180mm, surface coverage 40mm limestone particle with lime powder; Foundry goods reached room temperature after 124 hours, take out and carry out turning processing, and hardness HRB 240; Turning speed is 100-110m/s, and than 60-80m/s raising in the past, surface smoothness reaches Ra3.2.

Embodiment 3

90Cr18 foundry goods net thickness is 50mm, and physical dimension diameter 400mm adopts casing 800 * 800mm, and the 60mm limestone particle is laid in the bottom; Lay the 100mm lime powder above, the foundry goods that is heated to 950 ℃ is taken out from process furnace, put into casing immediately; Filled out foundry goods and covered cladding thickness 100mm, surface coverage 60mm limestone particle with lime powder; Foundry goods reached room temperature after 108 hours, take out and carry out turning processing, and hardness HRB 230; Turning speed is 100-110m/s, and than 60-80m/s raising in the past, surface smoothness reaches Ra3.2.

Claims (2)

1. method for annealing that improves Martensite Stainless Steel foundry goods cutting ability is characterized in that it may further comprise the steps completion:

(1), in the foundry goods take-in box, lay limestone particle:

The laying depth of limestone particle is 1-2 a times of casting thickness;

(2), lay lime powder:

The laying depth of lime powder is 2-3 a times of casting thickness;

(3), need insert in the foundry goods take-in box by the annealed foundry goods:

Foundry goods taken out in the heat tracing stove puts into the foundry goods take-in box immediately, the distance of the inner side-wall of foundry goods and foundry goods take-in box be casting thickness 3-5 doubly;

(4), add lime powder and cover foundry goods:

The cladding thickness of lime powder is 1.5-2 a times of casting thickness;

(5), cover limestone particle:

The cladding thickness of limestone particle is 20-60mm;

(6), treat to take out foundry goods behind the foundry goods cool to room temperature;

Described limestone particle particle diameter be 3mm-10mm, need be preheating to 200 ℃-300 ℃ before use;

Described lime powder, wherein the content of CaO is crossed 80 mesh sieves more than 85%, need be preheating to 200 ℃-300 ℃ before use.

2. according to right right 1 described a kind of method for annealing that improves Martensite Stainless Steel foundry goods cutting ability, it is characterized in that described foundry goods take-in box is casing or heatable adobe sleeping platform.