1. Vertical cracks - cracks characteristics and formation conditions: often occurs in parts, raw materials, ribbons and tissue segregation serious or not included in the longitudinal extension of the crack from the surface inwards, cracks deep, long hardenability.
Solutions and preventive measures: the elimination of the ribbon and tissue, isolation materials not excessive impurities; rational development of heat treatment parameters, as factors in human action.
2. shaped crack - the characteristics and formation conditions of quenching cracks: not often occur in quenching carburizing parts or components, parts and the thickness of the gap between the cracks located at the cusp.
Solutions and preventive measures: the key is to develop a reasonable heat treatment process parameters in order to improve the skills of the operators to try to eliminate the human factor in the operation; the best use of the design of the arc transition, to avoid sharp corners.
3. net cracks (also known as crack) - quenching cracks formation characteristics and conditions: the surface is very easy to produce such a grinding cracks. High hardness of parts, chemical treatment, induction hardening pieces tend to have such cracks, cracks in parts of the surface, a depth of about 0.005~0.02 mm.
Solutions and preventive measures: heat tempered full; grinding feed smaller amounts, reduce the heat generated when grinding.
4. stripped - the characteristics and conditions of crack formation: often seen in the surface hardening heat treatment or chemical ingredients. Transition zone release layer.
Solutions and preventive measures: immediately after quenching and tempering; a reasonable choice parameters and quenching medium.
5. micro-cracks - cracks more complex reasons for this.
Features and crack formation conditions: often in high-carbon steel, needle martensite, austenite grain boundaries and crystal defects in the memory of the organization.
Solutions and preventive measures to ensure that the chemical composition and structure of the material is in a normal state; the heat treatment process parameters must be strictly controlled, continuously upgrade their skills, to make up for some unforeseen factors, to avoid cracks.